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EXPERIMENT M3: - John A. Goree

1. 121 Repeat all the steps of 1 for the 195 shift register this time beginning by inputting the number 1111 Fill out the chart below Input After 1 clk After 2nd clk After 3rd clk J LO K LO QA QB QC pd ee ee ee QD J HI K HI QA QB QC QD J LO K HI QA QB QC QD J HI K LO QA QB QC QD 122 INSTRUCTOR NOTE usually steps b and c below should be omitted because the corresponding topics are not taught in lecture b Serial to Parallel conversion S gt P Observe QA to verify that when you present a datum to both the J and K inputs first two lines of truth table that the number is sent to the output QA on the clock Note that this allows 4 serial bits entered on four clocks to be readied for parallel output c Parallel to Serial conversion P gt S Examining the data in your diagram verify that the initial input data is converted into serial data where the output QD shows the input data as the clock is advanced 3 The 161 Synchronous Binary Counter This is a 4 bit binary counter with data inputs that can be preset 1 e programmed so that it begins counting from a desired number Binary counters contain JK flip flops Connect Vec to pin 16 and GND to pin 8 Connect the inputs of t
2. Apply the BCD input corresponding to 0 Touch a wire connected to an LED indicator to test the states of the 10 output pins Verify that the output pin corresponding to 0 is LO and the other outputs are HI Repeat with data inputs 1 and 8 132 Lab 10 Digital Meets Analog REFERENCE Horowitz and Hill Sections 8 20 one shot Section 5 14 555 timer Section 9 15 9 16 9 20 DAC amp ADC INTRODUCTION In this lab we will test IC s used to interface digital and electronic circuits The first is a popular chip for making oscillators the 555 Next is the monostable multivibrator One Shot which can produce a jitter free trigger signal from a rising or falling analog input Finally we will set up an digital to analog converter DAC and an analog to digital converter ADC EQUIPMENT Digital Oscilloscope Function generator Pulse generator DC power supply Prototyping board Capacitors 0 1 uF 3 0 01 uF 0 001 uF Resistor 3k 2 5 1k 2 10k 2 Integrated circuits 74121 one shot LM555 or 7555 timer DAC0808 8 Bit Digital to Analog Converter ADC0804 8 Bit Analog to Digital Converter Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 o The terms pulse generator and square wave generator refer to different things A square wave generator is usually a bipolar oscillator The waveform swings from positive to negative voltages Sometimes it has a feat
3. 151 Flip Flop 3 5V GND 117 a Basic operation Use Vcc 5 V and GND to power this chip Connect CLR pin 1 to a breadboard switch set to HI Provide data to the D1 input pin 4 from a prototyping board switch by setting the D1 input to HIGH Clock the flop pin 9 with a momentary contact switch for example logic switch A on the prototyping board Set up LED indicators of the input D1 output Q1 pin 2 and its complement Q pin 3 EA i Verify that the D flop ignores information presented to its input before a rising edge on the clock and that it then shifts that value to the output Draw a timing diagram showing CLK D1 and Q1 11 Verify the Truth Table in the data sheet by copying the truth table the figure labeled Function Table above by placing a check mark by each entry that you test and verify Label the state on the timing diagram that corresponds to each entry in the truth table b Shift Register Leaving the first flip flop set up as it is apply its output Q1 to the D2 input of another flip flop and so on for four flip flops total as shown below Connect the four outputs Q1 through Q4 to LED indicators Set CLR to HI using a switch on the prototyping board Use a clock frequency of about 1 to 10 Hz or use a momentary switch for example Logic Switch A on the prototyping board as a manually operated clock 118 IN 175 Meee pin 16
4. GND pin 8 clock 5V shift register Watch all the states Observe that the input is shifted to the right once each clock cycle Draw a timing diagram showing the four D inputs the final output and the clock The 195 4 Bit Shift Register CONNECTION DIAGRAM PINOUT A Shift Registers use a series of D flip flops with the output of one flip flop connected to the input of the next It accepts both series and parallel inputs and produces both series and parallel outputs Thus the 195 can be used to convert series input to parallel output and vice versa When LOAD is LO the outputs are set to the inputs on a rising edge of CLK When LOAD is HI the register shifts 195 Truth table INPUTS at ty OUTPUTS at tyne J K Qa QB Qc QD L L L QAN QBN QCN H H H QAN QBN QCN if H QAN QAN QBN QCN H L Qan Qan QBN OCN 119 Connect the 74LS195 to switches for input and LEDs to indicate output INPUTS OUTPUTS see note binary 23 22 2l 30 23 22 21 20 state IND INC INg INA CLK QD Qc QB Qa IC pin 7 6 5 4 10 12 13 14 15 board SW1 SW2 SW3 SW4 SWA LED1 LED2 LED3 LED4 Set CLR pin 1 to HI a Parallel data loading and serial shift Set LOAD to LO to allow parallel loading Input the number 0100 corresponding to inputs ABCD respectively To load this input number clock the chip by pressing SWA to cause a rising clock edge Confirm the number shows up on the LED indicators
5. It can be clocked by an external pulse source or by connecting a 141 resistor and capacitor to make a simple relaxation oscillator analogous to the way the 555 works we will do the latter here The ADC 0804 has two analog inputs for differential voltage measurement For convenience in testing this ADC we will ground one of the differential inputs pin 7 and to the other one pin 6 we shall apply a simple dc voltage One way of doing this is to use a voltage divider as a voltage source with an op amp voltage follower to assure a low output impedance The op amp follower is not critical here if you use a voltage source with a low output impedance to drive it Connect the ADC0804 as shown Use LED s on your prototyping board to indicate the three most significant bits pins 11 to 13 Pay careful attention to the grounds when using circuits with both analog and digital parts Although in this lab you may be asked to connect them together in general the analog ground and digital ground are different and some circuits might not work if you connect them toghether Use a bench power supply see photo as an adjustable voltage source Be sure its negative terminal is connected to its ground and connect that ground to your circuit s ground Vv 142 a b Clock Using an oscilloscope look at the waveform on pin 19 and print it Confirm that there is a5 V 100 kHz clock signal present This fre
6. The current that is sourced or sinked is determined by the emitter potential and the emitter resistor Rp A transistor current source is a far better current source than the crude voltage resistor combination you tested in Lab1 69 12V V R 1 load R 2 Re 1k current meter Figure 4 10 Use R1 22 k and R 33 k for the biasing resistors a Calculation Measure the component values Then calculate e the bias on the base e the potential at the emitter assuming an 0 6 V B E drop b Experiment CAUTION In using the current measurement function of the multimeter start at the highest possible range Using the 12 V power supply built into your prototyping board connect the circuit shown in Figure 4 10 For the load resistor use a decade box set to 2 kQ to begin i comparison to calculated values Measure and compare to the values calculated above the bias on the base the potential at the emitter ii current vs load resistance 70 Vary RL from 100 Q to 2 KQO in 100 Q increments Make a table of current vs load resistance iii compliance Determine the range of load over which the current remains constant to 10 Compare this result to your result in Lab 1 with the crude current source 71 Lab 5 Junction Transistor Part II REFERENCE Horowitz and Hill Sections 2 07 2 12 common emitter amp INTRODUCTION We continue the bi polar transistor experiments begun i
7. Verify that a HIGH on the input will cause the corresponding LED to be dark LOW amp Verify that a LOW on the input will cause the corresponding LED to be bright HIGH Write the truth table 1 e function table for the inverter Try using an LED in series with a 220 Q resistor instead of the LED built into the prototyping board to display the state of the gate s output 3 Quad 2 input NAND 74HC00 CMOS and 74LS00 TTL SN7400 N PACKAGE SN74LS00 SN74S00 D OR N PACKAGE TOP VIEW FUNCTION TABLE each gate INPUTS OUTPUT Y H H L L x H x L H 107 This chip has four NAND gates each with two inputs hence the name Quad 2 input NAND Look up the pin configuration in a data sheet The output pins are 3 6 8 and 11 Connect Vec to 5 V If you are using a prototyping board with built in input switches use these for the inputs and use the built in LEDs to display the outputs At first use the CMOS chip a NAND Figure 8 1la b Inverter with NAND Figure 8 1b c AND Figure 8 1c d OR Figure 8 1d e NOR Figure 8 le f Mystery NAND circuit Figure 8 1f See the pin diagram above amp Write down a Truth Table for each configuration listed above and check off every state as you test it Draw the gates amp Finally replace the CMOS chip with the TTL chip and verify that the chip works the same 1 e that the truth table for a is the same
8. You must always check this before using the scope to avoid X10 errors in your voltage measurements Push the TRIG MENU button and view the menu Sometimes in this course you will be asked to use EXT TRIG which you can accomplish with the digital oscilloscope by toggling Source to the Ext setting At other times you might wish to use CH1 as the Source 44 Build your triggering skills First choose AUTO trigger with the source specified as the same channel 1 or 2 as your probe While viewing the square wave from the probe adjust the trigger level knob up and down while watching the display Observe that when the trigger level is adjusted too high or too low there is a loss of triggering and this can casuse the displayed waveform to be unstable in the horizontal direction Next repeat with NORM rather than AUTO trigger In this mode the scope will not update the display unless there is a valid trigger event unlike the AUTO mode which will trigger occasionally even when there s no valid trigger event just so that you can see at least something on the display Push the MEASURE button and view the menu Toggle the Type setting to measure the peak to peak voltage and the frequency of the waveform Then adjust the TIME DIV knob so that less than one full oscillation is shown and notice how the scope is unable to measure frequency 0 5 Digital Oscilloscope Skills Use th
9. _ Power Supply Rectifying Circuits a Half Wave Rectification Set up the circuit as sketched here For this part ignore the center tap CT terminal on the transformer if any You are building a power supply so use power diodes rated at 1 W not the little signal diodes Use the decade box set at 1 KQ for the load resistor Scope i Input 1 PRI SEC m Scope Input 2 8 VAC RL Ee Scope Ground 110 VAC variac transformer Caution do not use the insulated mini grabber connectors to connect the transformer to power diodes they can melt and they are costly Use alligator clips and arrange the components on your prototyping board so that the alligator clips will be separate by gt 2 inches so that they don t short Ifusing an analog scope set the oscilloscope as follows Anis ins i input coupling DC CH1 and CH2 vertical mode BOTH and either ALT or CHOP this is the dual trace feature In the figure below the waveforms are shown as they would look if the input voltage had a 1 V amplitude Notice the 0 5 V diode drop Also notice the time interval shown between the dashed lines when the input voltage is positive but not large enough for the diode to conduct 48 Half wave rectification shown for input of 1 V amplitude time Adjust the variac to indicate 10 VAC output Measure the P P amplitude of o the input voltage V from the transformer o the rectified sine wave output voltage V
10. ee Use a magnifying glass to read the part numbers of your diodes and to distinguish the signal zener and power diodes Use your oscilloscope or a second multimeter to determine which of the multimeter leads has a voltage and which is Look at your multimeter to see what special features it has You can do a diode check with the resistance function on the 200 Q scale Even better try the diode check feature as shown by the symbol if your multimeter has one some models indicate the diode drop voltage if the diode is not damaged The diode check function will display the diode s voltage drop across the PN junction Confirm the PN polarity of a signal diode these are smaller than the power diodes Look at the markings on the diode to see how they show the polarity Repeat the diode tests above using a power diode Note that for a multimeter check to work the multimeter must apply a voltage of at least 0 5 Volt between its two leads to bring the diode into conduction when it is forward biased CAUTION In this lab it is possible to burn up components if you are not careful to make sure everything is correct before turning on the power e Please note all caution statements in these instructions e Double check before turning power on e When using the decade box do not set the load resistance below 50 Q 42 Learn to use the digital oscilloscope amp a scope probe no writt
11. notice whether the pulse generator produces a more ideal square pulse than the square wave from the function generator Look for ringing i e unwanted oscillations After you ve finished with the delayed trace e Set the scope to Horizontal Mode A so that you are no longer viewing the delayed sweep e Pull the time base knob out so that the mark on the inner knob is aligned with the two black marks on the clear outer knob now they will move together when you adjust them Be sure that the vertical coupling of CH1 is set to be DC e On the pulse generator vary the following and observe how the waveform changes o Vary the vernier for pulse period o Vary the vernier for the pulse width up to a maximum of 50 of the pulse period o Switch between NORM and COMPL output 36 Use these blank oscilloscope screens to sketch waveforms shown on an analog scope 37 Use these blank oscilloscope screens to sketch waveforms shown on an analog scope 38 Lab 3 Diodes Power Supplies Zeners and SCR s REFERENCE Horowitz and Hill Sections 1 25 1 30 rectification filtering regulation Sections 6 11 6 14 power supply parts Sections 6 16 3 terminal regulator INTRODUCTION In this lab we examine the properties of diodes and their applications for power supplies and signals Diode rectification in 1 2 wave and full wave bridge circuits Filtering in power supply circuits 3 terminal voltage regulat
12. 2010 Amplifier Transistors NPN Silicon MAXIMUM RATINGS Total Device Dissipation Ta 25 C 625 mW Derate above 25 C 5 0 mW C 1 5 Total Device Dissipation To 25 C Watts Derate above 25 C CASE 29 11 STYLE 17 Operating and Storage Junction TO 92 TO 226AA Temperature Range THERMAL CHARACTERISTICS OOO mnene S Symbol wax unt COLLECTOR BASE ELECTRICAL CHARACTERISTICS Ta 25 C unless otherwise noted a A OFF CHARACTERISTICS Collector Emitter Breakdown Voltage V BR CEO 40 Vde lc 10 mAde Ip 0 Collector Base Breakdown Voltage V BR ceo 75 Vde lc 10 nAde le 0 Emitter Base Breakdown Voltage Vi BRIEBO 6 0 Vde le 10 nAde Ie 0 Collector Cutoff Current lcex 10 nAdc Voe 60 Vdc Vego 3 0 Vdo Collector Cutoff Current lego uAde Vee 60 Vde le 0 0 01 Vp 60 Vdc le 0 Ta 150 C 10 Emitter Cutoff Current 10 nAde Ves 3 0 Vde Ic 0 Collector Cutoff Current lcEo 10 nAdc Voce 10 V Base Cutoff Current Voe 60 Vdc Vegior 3 0 Vdo ELECTRICAL CHARACTERISTICS Ta 25 C unless otherwise noted Continued aaa 0 Be ON CHARACTERISTICS DC Current Gain lc 0 1 mAde Vee 10 Vdo lc 1 0 mAde Vce 10 Vde lc 10 mAde Vce 10 Vde lc 10 mAde Vce 10 Vde Ta 55 C lc 150 mAde Vce 10 Vdc lc 150 mAde Vee 1 0 Vde lc 500 mAde Vce 10 Vdo tt Collector Emitter Saturation Voltage VE sat Ig 150
13. 2N25107 2N3904 2N35106 NPN PNP TO 92 case TO 18 case The 2N3904 and 2N4400 are similar except that e 2N4400 withstands a higher collector current and is therefore better suited for switching circuits you may you may substitute 2N2222 for 2N4400 e 2N3904 is better suited for signal amplifier circuits 1 Multimeter Check of Transistor This test is similar to the one you did in Lab 3 with the diode If you are unsure of how to do this test first go back to Lab 3 and repeat the diode test 61 collector base of r B emitter E Figure 4 3 a Diode equivalent A Use your multimeter s diode check feature It will display the forward bias voltage Verify that the transistor looks like two diodes as shown in Figure 4 3 b Beta measurement amp If your multimeter has special connectors labeled C B E then it has a transistor check function For some multimeters this will display the beta or hpg Try it For the 2N3904 beta is typically hpg 210 Emitter Follower a Emitter Follower Operation Using the 12 Volt power supply that is built into your prototyping board wire up an NPN transistor as an emitter follower as shown in Figure 4 4 12V Xec 10k oN 2N3904 12V Figure 4 4 62 POWER SUPPLY Figure 4 5 Power supply on prototyping board left Connect these using wires to the strips sketched on the right for convenient use Hint On your prot
14. Digital Multimeter Digital ICs TTL LS or CMOS HC 7400 Quad NAND 7442 BCD to Decimal Decoder 7447 BCD to 7 segment decoder driver common anode 7490 decade counter 74112 JK flip flop 74175 D flip flop 74161 4 Bit Synchronous Binary Counter 74195 4 Bit Shift Register Capacitors 0 1 uF Resistors 150 Q 10 k 2 Seven Segment LED common anode LN513RA or LSD332X XX Wires for Prototyping board 35 for 7 segment Switch SPDT momentary contact with wires attached for de bounce Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 PRELAB Explain the difference between parallel and serial e what is meant by parallel input e what is meant by serial shift 116 PROCEDURE D Flip Flop 74HC175 or 74LS175 The D Flip Flop is the simplest but most important Flip Flop It simply saves at its output Q what it saw at its input D just before the most recent clocking edge The chip used below the 175 has four flip flops and they respond to a rising edge on the clock input Dual In Line Package Vcc a4 a4 D4 D3 3 Q3 CLOCK Function Table Each Flip Flop H High Level steady state L Low Level steady state X Don t Care T Transition from low to high level Qo The level of Q before the indicated steady state input conditions were established CLEAR Q1 Q1 01 D2 Q2 Q2 GND TLF 6557 t Order Number 54175DMQB 54175FMQB DM54175u DM54175W or DM74175N CLEAR 2
15. GND CAL knob fully clockwise to click CH2 same as CH1 set INVERT switch to the out position These instructions are for Tektronix 2235 other analog oscilloscopes are similar 24 horizontal mode A time base A sec div 1 ms CAL knob fully clockwise to click var holdoff NORM A trigger P P AUTO level turn to approximately middle of knob s range slope out A amp B INT CH1 A Aano B SEC DIV A source INT A ext coupling DC Once you have found a trace that looks like a horizontal line use the vertical position knob on CH1 to position the trace in the center of the display Then change the CH1 coupling to DC Connect the output of an adjustable power supply to the oscilloscope input CH1 You should see a trace at a non zero voltage Change the CH1 coupling back and forth from GND to DC to see the difference Set your power supply to three different DC voltages and measure each voltage with both the oscilloscope and the digital multimeter Adjust the display intensity as low as practical so that the trace is a thin line Compare the DC voltage measurements of the oscilloscope and the digital multimeter Report the measurement uncertainty error values based on the specifications for the multimeter and the oscilloscope and your impression of how precisely you can read the oscilloscope display Which is more precise the meter or the oscilloscope b AC Voltages Connect the function gener
16. Operating point Connect the circuit shown above using a prototyping board In wiring it up it may be easiest if you use three of the long thin rails on the prototyping board for 12 V GND and 12 V Measure and compare to the calculations above i the dc base bias and the emitter potential ii the collector current use Ohm s Law and a measurement of the potential across the collector resistor to determine this c Voltage gain Sync output 75 of function generator i with emitter bypass capacitor Set up the function generator to produce a 5 kHz sine wave with a low output amplitude Set up the oscilloscope to make a dual trace measurement of the input and output of the amplifier Connect the SYNC output of the function generator to the EXT TRIGGER input on the scope and use external triggering Make sure that the grounds of the oscilloscope the prototyping board and the function generator are all somehow connected Adjust the function generator amplitude to produce a good sine wave on the output of your amplifier If the output waveform is saturated or clipped reduce the input amplitude from your function generator If it is necessary to reduce the input amplitude further wire up a k potentiometer as an adjustable voltage divider and connect it between the output of the function generator and the input of the amplifier amp Measure the input and output amplitudes using the oscilloscope
17. SS LOGIC INDICATORS ere ef ee e on OQ L1 L2 L3 Lg Your prototyping board has built in LED Logic Indicators that you can use for displaying a signal As an alternative you may use a discrete LED as an indicator but be sure to use a series resistor as described below How to read part numbers The part number consists of numbers and letters Example SM74LS00 the SM indicates that the manufacturer is Motorola and this is not important 7400 indicates that the chip is a quad 2 input NAND and the LS indicates that it is a variety of TTL that is low power Schottky input Other chips that perform the same logical function are 7400 plain old fashioned TTL and 74HC00 High speed variety of CMOS All of these chips are logically identical and their pin configurations are the same About CMOS 104 CMOS is more common nowadays than TTL because it has a lower power dissipation Nevertheless your instructor may prefer TTL for this course because TTL chips unlike CMOS are immune to damage by static electricity Static electricity can destroy CMOS chips To avoid damage e store unused chips properly in special plastic tubes or special plastic bags e before handling a CMOS chip ground yourself by touching a ground such as the metal cover plate on an electrical power outlet on wall About the light emitting diode LED In building digital circuits you will often use an LED as an indicato
18. across the 1 KQ load resistor Ry Print the input and output waveforms and compare the peak output voltage with half of the PP input voltage Explain the difference Repeat without the variac i e with the transformer powered directly from a 110 VAC outlet so that the waveform from the transformer has a larger output b Full Wave Rectification CAUTION In this part carefully check the polarity of your diodes before turning on the 110 VAC power otherwise you may burn up the diodes amp Measure the output waveform of the full wave bridge circuit in Figure 3 3 Do not attempt to measure the input waveform Use a 1 KQ load resistor Print the output waveform Compare to the half wave rectifier 49 Scope Input 110 VAC Scope Gnd Figure 3 3 Full wave rectifier bridge circuit The input is 110 VAC line voltage 4 _ Power Supply Filtering CAUTION In this part carefully check the polarity of your capacitor before turning on the 110 VAC power Starting with the full wave rectifier circuits in Figure 3 3 add a capacitor C 100 uF across the load resistor as shown in Figure 3 4 Note that capacitors of such a large value are polarized one L of the capacitor s two leads is marked or 100 uF gt Figure 3 4 Filter Capacitor Measure the DC output voltage Measure the PP AC ripple using the oscilloscope Try this two ways e first with DC input coupling e repeat with
19. board for Vec Veg 15 V should work too As with many circuits this one can benefit from adding a filter capacitor across the power supply leads to reduce problems arising from voltage drops appearing on the power supply It is recommended to add a 10 uF capacitor across the power supply pins 8 and 1 position this capacitor within a few millimeters of the 555 chip Note the polarity of the leads of the electrolytic capacitor Use the oscilloscope to observe the waveforms at the output and at pin TH Measure the duty cycle of the output waveform Duty cycle fraction of time the output voltage is high Specify your answer in percent e g 37 5 5 Z Measure the frequency Compare it to the predicted value fose 1 0 7 Ra 2Rp C Replace Rp with a short circuit Describe the resulting waveform Explain your observation Leave this circuit hooked up You will use it with the one shot in the next part 137 555 Timer square wave oscillator Monostable Multivibrator One Shot 74LS121 The output of a one shot is a digital pulse triggered by an analog waveform at its input Even if the input is noisy the one shot will produce a clean pulse The pulse has a width determined by an RC time and the pulse height is determined by the input voltage 138 SN74121 N PACKAGE FUNCTION TABLE TOP VIEW mea a a vcc En NC NC E Al NC H H xX A2 Rext Cext ae a eqs softer om Q Rint E GND NC
20. i serial shifting Now set LOAD to HI to allow serial shifting Clock the register by pressing SWA to advance the data you will need to do this to move the data forward Connect J and K to one of the four possible input combinations shown in the truth table amp Examine QB Qc and QD on the LED indicators to verify that the register shifts data serially in the direction A to D as indicated in the truth table Fill in the chart on the next page Repeat for the four combinations of J and K The first combination J LO and K LO is pre completed to show you what is expected for this combination just verify that what is pre completed is correct ii truth table Examining your chart verify by ticking a box in a skinny column that the part of the truth table that indicates that upon a shift state A is filled with either a LO a HI the previous value or the complement of the previous value depending on the values of the J and K input 120 Chart for 195 shift register The lines of this table highlighted in gray have already been completed as an example of the desired style Input After 1 clk After 2nd clk After 3rd clk J LO K LO QA QB QC QD SS SSE SSeS SSS J HI K HI QA QB QC QD J LO K HI QA QB QC QD J HI K LO QA QB QC QD
21. if the lab is equipped with more than one type of scope ask your TA 34 Adjust the B DELAY ten turn knob until you find the trailing edge of the square wave waveform You may have to adjust the B intensity knob to see the trace start off with the B intensity knob in a central position Measure the decay time of the trailing edge Do you see ringing i e unwanted oscillations Does the function generator produce this ringing at much lower frequencies as well Repeat with the leading edge 35 Learn to use the pulse generator Repeat the steps above using the delayed sweep but this time use the Pulse Generator instead of the Function Generator The purpose of this exercise is to learn about pulse generators and to further develop oscilloscope skills O For the output use the pulse generator s right most BNC connector Adjust the HP pulse generator so that it has the following settings OUTPUT Sliding switches RATE Hz PULSE PERIOD s Pulse period 20n 1 u EXTE 20n 1p Am 10m 1 Pulse delay adjust to minimum ee le Pulse width 10n 1p a Amplitude adjust to maximum Pe PULSE DELAY s NORM 35n 1p im gt 10m 1 Other switches aa Pulse Norm Offset Off 4 PULSE WIDTH s l 10n 1p Am gt 10m 1 Output Norm CO a E Int Load IN VERNIER Verniers Pulse period 3 O Clock position Pulse width 12 O Clock position f Amplitude 12 O Clock position When examining the delayed traces
22. input and the 4 BCD outputs indicated by 4 LED s Check the part number on the 7 segment display If it differs from the SEA 3210 specified here you will need to check the pin diagram for your display this can be done by searching the internet for the part number and looking for a data sheet Connect the BCD outputs of the BCD counter to the BCD inputs of the 7447 Connect the 7447 to the 7 segment LED display as shown Note pin configurations for LED displays is not standardized Pin configurations are shown here for the SENIOR SEA3210 display Your display might have a different model 127 number but the same pins This display has an additional LED for a decimal which we will not use a Counting amp Write a copy of Table 9 1 and check off each state 0 through 9 to confirm that the LED outputs D C B and A of the counter are properly indicated by the LED display b Current consumption amp Use your multimeter in the dc current mode to measure the current from the common anode to the 5 V Vec How much current is consumed by the LED display when the display reads 1 and when it reads 8 Note that LED displays are power hungry devices 5V Voc IE 74LS47 anode GND A B C D BCD inputs LSD3222 XX 7 segment common anode LED top view a 14 NC ie 13 b note this LED display does not anode 3 12 NC actually have 14 leads but the package NC 4 11g is shaped like a 14 pin DI
23. measure a DC voltage and get 5 30 Volt 1 2 The uncertainty is given as 0 5 of the reading or 0 005 x 5 30 plus 1 x LSD where the LSD is 0 01 here So the uncertainty is 0 005 x 5 30 1 x 0 01 0 0365 Volt 4 Rounding to 0 04 your result is 5 30 0 04 Volt 0S vii Agilent 34410A Multimeter Accuracy Specifications of reading of range Function Range Frequency 24 Hour Test Current or Teal 1 C Burden Voltage DC Voltage 100 0000 mV 0 0030 0 0030 1 000000 V 0 0020 0 0006 10 00000 V 0 0015 0 0004 100 0000 V 0 0020 0 0006 1000 000 vt 0 0020 0 0006 True RMS 100 0000 mV 3 Hz 5 Hz 0 50 0 02 AC Voltage to 750 000 V 5 Hz 10 Hz 0 10 0 02 10 Hz 20 kHz 0 02 0 02 20 kHz 50 kHz 0 05 0 04 50 kHz 100 kHz 0 20 0 08 100 kHz 300 kHz 1 00 0 50 Resistance 100 0000 Q 1mA 0 0030 0 0030 1 000000 kQ 1 mA 0 0020 0 0005 10 00000 kQ 100 pA 0 0020 0 0005 100 0000 kQ 10 pA 0 0020 0 0005 1 000000 MQ 5 pA 0 0020 0 0010 10 00000 MQ 500 nA 0 0100 0 0010 100 0000 MQ 500 nA 10 MQ 0 200 0 001 1 000000 GQ 500 nA 10 MQ 2 000 0 001 DC Current 100 0000 pA lt 0 03V 0 010 0 020 1 000000 mA lt 03 V 0 007 0 006 10 00000 mA lt 0 03V 0 007 0 020 100 0000 mA lt 0 3 V 0 010 0 004 1 000000 A lt 08 V 0 050 0 006 3 000000 A lt 20 V 0 100 0 020 True RMS 100 0000 pA to 3 Hz 5 kHz 0 10 0 04 AC Current 3 00000 A 5 kHz 10 kHz 0 20 0 04 Freque
24. multimeter to operate in its highest current range to begin with use it to measure the current flowing through the lamp Setting your multimeter to measure voltage measure the voltage drop across each of the two resistors Compute the current flowing into the base Comparing these two currents is it true that the cold switch allows you to switch a larger current through the load lamp than passes through the actual switch c Saturation mode amp With the switch closed use your multimeter to measure the DC voltage drops VCE and Vg E Z Is Vc lt Vg as expected for saturation 68 d Cold switching from a pulse generator s output lt 5V bc out pulse 47 lamp generator gnd Replace the manual switch with the pulse generator s output as shown in the diagram so that a high output from the pulse generator will cause the lamp to light Adjust the pulse generator to produce its maximum output voltage and maximum period choosing a square wave output Observe the collector voltage waveform on an oscilloscope with DC input coupling and the time division adjusted to a long time Verify that the lamp is turned on and off periodically Print the oscilloscope display and mark the waveform indicating when the lamp is on and off Measure the period using the oscilloscope Current Source A current source Figure 4 10 will supply a constant current to a range of load resistances
25. of clipping Print the output of the clamp circuit for sine wave inputs two ways o With an output waveform that is severely clipped o With an output waveform that is only slightly clipped Comment quantitatively on the output amplitude where clipping is strongly observed and explaining what parameter for a diode determines this clipping amplitude in 1k out Diode Limiter 2 Diode Clamp Connect the clamp circuit in the figure Use the 5V power supply built into your prototyping board This is a low current application so you use signal diodes not current diodes Connect the input of this circuit to the function generator with a sine wave at 10 kHz Check that the 20 dB attenuator switch on the function generator is not activated 46 Set up the oscilloscope to show the input and output waveforms Use DC input coupling on the oscilloscope Connect three grounds together the ground of the 5 V power supply the ground of the function generator and the ground of the oscilloscope Adjust the sine wave amplitude so that you can see a clamped output Print the waveforms for the input and output of the clamp circuit If you can see that the clamped voltage is not quite flat then you can see the effect of the diode s non zero impedance in conduction From your observation explain in one or two sentences what the clamp circuit is useful for in 1k out Diode Clamp 5 V 47 3
26. output 109 Dual In Line Package DATA INPUTS DATA SELECT _ _ er aT Veco 0a D5 D6 D7 B Cc H S i L L L L L L H High Level L Low Level X Don t Care D3 D2 D1 DO Y W STROBE GND DO D1 D7 the level of the respective D input Va DATA INPUTS OUTPUTS TL F Order Number 54LS151DMQB 54LS151FMQB 54LS151LMQB DM54LS151J DM54LS151W DM74LS151M or DM74LS151N Connect the 74LS151 as shown below DATA SELECTS OUTPUT binary 22 21 20 state C B A Y IC pin 9 10 11 5 board SW1 SW2 Sw3 LED1 Set the following pins on the 74LS151 to LO Strobe pin 7 All inputs except D1 a The intended use of the chip multiplexing Predict by examining the truth table which combination of input states A B and C will result in an output Y that is HI or LO if D1 is HI Write your predictions in the form of a table with four columns C B A and Y Repeat for D1 LO Operating the circuit with D1 high and then D1 low verify the two truth tables you predicted above you can indicate a successful test with a checkmark to the right of a row b Another use for the chip XOR 110 Predict by examining the truth table which combination of data input states DO D7 will result in the output Y that is a two input XOR using A and B as the inputs to the XOR Write your prediction as a two column list with DO D7 listed in the left column and in the right column write either A XOR B or
27. photodiodes faster time response but less sensitive e photo darlingtons these are like a phototransistor but include an additional transistor to provide additional gain at the expense of a slower time response e photomultiplier tubes a vacuum tube with a very fast time response Measurement skills you will learn in this lab include e using a digital oscilloscope to measure a high speed pulse e using a 10X probe which is useful because it has a higher bandwidth and faster time response than a 1X probe Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 66 Overshoot A pulsed waveform does not transition instantly between two levels Instead it follows a curve which asymptotically approaches the final level In some cases a waveform will overshoot the final level Voltage overshoot Square wave with overshoot 66 Rise time and fall time The speed of switching between the two levels is characterized by a rise time and fall time These are often measured as the time interval between the 10 and 90 voltage levels as shown below Sometimes however a criterion different from the 10 90 rule might be adopted voltage V Vo Ve Vo 90 time I 1 1 risetime falltime 78 EQUIPMENT Digital Oscilloscope Pulse generator HP8013B DC power supply Prototyping board 10X probes 2 and a manual for this probe model Resistor 270 1k Light em
28. regardless of the amplitude of the waveform or the student performing the test it is a criterion determined by the oscilloscope s manufacturer Things to know about measuring speed The rise time that you measure for the output of the phototransistor is tens of microseconds This is the result of the rise times of several components and instruments e Oscilloscope The oscilloscope has a bandwidth that is probably printed on top of its front panel If it has a bandwidth of 100 MHz for example it will have a rise time of about 0 35 100 MHz 3 5 nsec Faster oscilloscopes cost more e Probe The 10X probe also has a bandwidth that limits how fast the measurement of the waveform can be made look in the manual for the 10X probe to find the specification for rise time Record this value e Pulse generator The rise time for the pulse generator is finite but it is much better than for an inexpensive function generator Pulse generators are optimized to produce excellent pulses with fast rise times function generators are not e The phototransistor and LED have finite response times here are the data from the manufacturer s specifications PNAI801L phototransistor 4 usec typical HLMP C115 LED 30 nsec typical e The HLMP C115 LED which costs about 0 60 is one of the fastest visible LEDs that I was able to find Usually in applications where the response time of a light source is important you would not choose an LED in
29. so that the comparator circuit s output voltage will change when you cover the sensor with your hand to block the room lights The voltage divider should consist of the photocell and a suitable fixed resistor and it should be connected to a suitable power supply It may be helpful to know that indoor room lighting is typically in the range of 10 100 foot candles Whether this circuit works will depend on your choice for the voltage divider resistance power supply and threshold voltage for the comparator You must decide on your own what values to use for the resistance and what to use for the voltage divider s power supply After designing the circuit verify that the output of the comparator changes when you block unblock room lights from hitting the photocell and report the values you chose for the resistor and the power supply voltage for the voltage divider 99 Lab 8 Digital Gates REFERENCE Horowitz and Hill Sections 8 01 8 13 INTRODUCTION Digital devices are basically electronic switches that use two states or logic levels TTL and CMOS are two families of digital circuits Most commonly they are powered by a 5 V power supply although CMOS is sometimes used with 12 V These are integrated circuits i e IC s or chips A digital signal is either ON or OFF state other names for the state TIL CMOS ON HI 1 TRUE 3 0 5 5 V 3 5 5 5 V or 8 5 12 5 V OFF LO 0 FALSE 0 5
30. to Ohms Check the meter by shorting the test leads The meter should read zero ohms a Tolerances note if you are color blind skip this step and inform the TA For this step only use the box of assorted resistors Measure the resistance of six of your resistors Use only resistors with four bands resistors with five bands are uncommon sometimes the fifth band is used to indicate temperature sensitivity or to provide an additional significant digit for the resistance value Determine the fractional error from the nominal value from the color code Make a table with seven columns color code nominal value tolerance measured value multimeter scale multimeter error multimeter error as a fraction of measured value How many of the values fall within the specified tolerance t If you are color blind you will be unable to identify the colors on the resistors Inform the TA so that you can be excused from this step Otherwise in this course you will need to rely on your multimeter to determine your resistor values if you are unable to read the color code As always draw the schematic For this measurement see Fig 1 3 b Series amp parallel Choose two resistors that are within a factor of ten of the same value Wire them up in series and then in parallel using the board with three terminals Measure the series and parallel resistances amp Calculate the expected resistances use measured va
31. 011 when you first turn on the power If this happens just apply several pulse inputs until a new cycle begins ii resetting amp Verify by copying the first two rows from the Mode selection table above and placing check marks by the entries as you test and verify them that setting both the reset inputs MR1 and MR2 to HI will zero the outputs at D C B and A of the decade counter 126 To avoid wasting time do not take this circuit apart yet Leave this circuit wired up for use with the 7 segment display in the next part Table 9 1 decimal BCD DCBA 0 0000 1 0001 2 0010 3 0 0 11 4 0100 5 O0 101 6 0110 7 O 1 1 1 8 100 0 9 1001 0 000 0 etc Decoder Driver and 7 Segment LED Display 7447 Forewarning this circuit is not hard but it requires hooking up more wires than most thus it might take more time Displays are popular output devices LED s are brighter while LCD s consume far less power Both types of displays require a decoder driver to convert decode from BCD input and to drive the display LED displays have 8 leads for the 7 LED s The displays and their corresponding driver IC s come in two varieties common anode and common cathode Ordinarily when using LED s one uses a series resistor of about 150 Q to limit the current Leave the BCD counter hooked up as it was at the end of part 5 above with a switch for the
32. 1 5 V 0 5 1 5 V Digital ICs called gates perform arithmetic and logical operations one input NOT inverter two or more inputs OR AND NOR NAND XOR Exclusive OR On 14 pin logic chips usually pin 14 is Vec 5V and pin 7 is ground We will try out these devices and their truth tables then combine them to perform more complicated logical operations We will also test a half adder which perform the arithmetic operation of addition and a multiplexer Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 EQUIPMENT Prototyping board Power supply Digital multimeter Resistors 220 Q 1 LEDs 4 Digital ICs 74HCO00 and 74LS00 74LS02 or 74HC02 74LS04 or 74HC04 74LS86 or 75HC86 74LS151 101 Quad NAND Quad NOR Hex inverter XOR 8 Input Multiplexer A BASIC FACT TO KNOW In electronics e It is USUALLY OK to connect an output of a circuit to the inputs of two circuits e Itis NEVER OK to connect two outputs together 102 PRELAB 1 Look at all the diagrams in this lab and verify that you are never asked to connect two outputs together although you are often asked to connect an output to multiple inputs 2 Refer to a textbook e g Horowitz and Hill text p 495 to find the truth table for a 2 input XOR gate Copy that truth table in the form of three columns inputs A and B and output Q Repeat for a 3 input XOR with three inputs A B and C The exclusive or
33. 29 128 Electronics Laboratory Manual John A Goree Department of Physics and Astronomy The University of Iowa Updated for Spring 2010 Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 TABLE OF CONTENTS page Preface iii Lab Notebooks iv Lab Reports v Symbols Used in this Manual vi Resistor Color Code vi Treatment of Experimental Errors vii To the Instructor ix Lab Weeks typical l DC Measurements l 2 AC Measurements 1 5 3 Diode Power Supplies Zener SCR 1 2 4 Junction Transistor Part I 1 2 5 Junction Transistor Part II 0 5 6 Optoelectronics can be scheduled any time after Lab 4 0 4 l Operational Amplifier 1 5 8 Digital Gates 1 9 Flip Flops Shift Register Decade Counter Decoder LED Display 1 3 10 Digital Meets Analog 1 Special project 4 An average student will require approximately 3 hours to complete a lab that is indicated as 1 week Some students will require more than 3 hours Lab grades will be weighted by the number of weeks shown when computing the lab component of the course grade PREFACE GOAL The purpose of the experiments described here is to acquaint the student with 1 analog amp digital devices 2 design of circuits 3 instruments amp procedures for electronic test amp measurement The aim is to teach a practical skill that the student can use in the course of his or her own experimental research projects in physics astronomy or anothe
34. 3 a R input C output oscilloscope CH1 displays the input waveform CH2 displays the output waveform BNC cable SYNC OUT FUNCTION labeled TTL GENERATOR red wire OUTPUT banana plug cables red wire Figure 2 3 b black wire 30 4 R C Low Pass Filter a Amplitude Response Use the same circuit as above in Figure 2 3 b Set the function generator to produce a sinusoidal output with an amplitude of about 4 or 5 V peak to peak Use a 1 2 5 frequency sequence from 500 Hz to 10 Hz i e 500 1000 2000 5000 Hz Also include a frequency of f 1 22RC in this sequence as calculated from measured values of R and C 1 Record a table of your data with columns for f Az error bar for f Vin oscilloscope scale for Vin error bar for Vin Vout oscilloscope scale for Vout error bar for Vout Vout Vin ii Plot the voltage ratio Vout Vin with log log axes with frequency on the horizontal scale Make a theoretical plot of Vout Vin on the same graph You may use Graphical Analysis or other software to create the graph using the instructions below a Compare the frequency at Vout Vin 0 707 to f 1 22RC b Phase Response Use the same circuit as above Measure the phase shift of the voltage across the capacitor relative to the input voltage from the oscillator for the same frequency sequence as for the amplitude response above i Record your data with colu
35. AC input coupling You should find that AC coupling allows you to use a smaller scale in Volts div and thereby make a more accurate measurement Print the output waveform Discuss in one sentence how the filter capacitor improves the performance of a power supply Repeat with a capacitance of 1000 uF Using the capacitance of 100 uF try a smaller load resistance CAUTION do not set the load resistance below 50 Q List your results Compare with the calculated values of the DC output and ripple voltages See text p 46 Discuss in two or three sentences two factors that cause ripple to become worse 50 Note that in a power supply a bigger capacitance gives better filtering but with the tradeoff that the component is costlier larger and heavier 66 Note that the smaller the load resistance i e the larger the current that the power supply must deliver the worse the ripple Do not disassemble the full wave rectifier yet 5 Voltage regulation with 3 terminal regulator C TO 92 7 Plastic Package Z 3 terminal voltage regulators are easy to use A 1 INPUT From the outside it looks like a transistor but on the inside there is a good regulator that makes use of negative feedback It features thermal oak protection so that it is hard to burn up in pso07744 3 out GND Bottom View a Simple test Connect the 78L05 regulator on your prototyping board as shown below For an input use th
36. C DIAGRAM CONNECTION DIAGRAM DIP TOP VIEW PIN NUMBERS Vcc PINS GND PIN 10 NC NO INTERNAL CONNECTION 124 LS90 MODE SELECTION RESET SET INPUTS OUTPUTS Qo Q1 Q2 Q3 H HIGH Voltage Level L LOW Voltage Level X Don t Care Connect the 90 as follows note the unusual power supply pin assignments 5 10 input GND GND NC 5 V GND GND QC 9 QB 10 GND 11 Qp 5 output 12 QA 2 output 13 NC 14 2 input OR Oy a ee eS For an input in parts a to c use the pulse generator to produce square pulses between 0 and 5 V at 5 kHz If you have difficulties below in getting a desirable signal from the outputs of the chip check the input waveform it sometimes helps to set the pulse generator s INT LOAD switch to the in position Set up a scope for dual trace operation to show the pulse input from the pulse generator and an output either pin 11 or 12 depending on what you are measuring of the 90 Trigger the scope internally using as the trigger source the scope channel CH1 or CH2 that you have connected to the counter s output amp Use the 90 to perform the following operations a Divide by 2 Connect the pulse input to the 2 input amp Print the waveforms Discuss briefly the meaning of the phrase divided by two as it is shown by your waveforms identifying which parameter is divided b Divide by 5 Connect t
37. Compute the gain and compare to the theoretical value using measured component values from above Is this an inverting amplifier ii without emitter bypass capacitor Repeat these steps with the bypass capacitor disconnected Note if clipping occurs check that you have not shorted the emitter Cr d Input impedance Measure the ac input impedance of the circuit with the emitter bypass Use the procedure from Lab 4 Compare to the theoretical value from above e Output impedance Measure the ac output impedance using the procedure from Lab 4 76 Lab 6 Optoelectronics REFERENCE Horowitz and Hill rise time p 268 optoelectronics pp 590 598 INTRODUCTION The term optoelectronics refers to semiconductor light sources and light sensors Light sources include light emitting diodes LED and laser diodes In this lab you will use a visible LED LED s are cheaper and are usually used as visual indicators rather than for high speed communication Laser diodes are more expensive and are used for high speed fiber optic communication In addition to their high speed in turning on and off laser diodes have the advantage of producing a narrower spectrum of wavelengths helps overcome the dispersive effects of glass where different wavelengths travel at different speeds There are many kinds of light sensors In this lab you will test a photo transistor Other light sensors include e
38. INYJA Pulse Generator te oe LNd LNO ll WON _ indLNO INdNl INdNi 31v9 Y39914 b wor wp d uo JAVM L__ awenos S HLOIM 3S1Nd dt uge WHON 378nN0G 3S51Nd s AVIS0 3S1Nd i ool XOL WOS L wor wy gt my uz S GOINad 3S1Nd ZH QuYVH OVd L137M3H YOLVYANAD 3SINd sELOs8 21 TA Instructions Before the students begin this lab demonstrate the following tricks for using an analog oscilloscope Checking trace rotation O Adjust the intensity as low as practical so that the trace is a thin curve o Use GND coupling to produce what should be a horizontal line o Use the vertical position to move the curve to the middle of the display O Verify that the trace is aligned with a horizontal gridline that is shown permanently on the display O If not aligned the scope requires using a small screwdriver to adjust the trace rotation this is required for approximately one out of ten oscilloscopes each year Measuring amplitude O Adjust the intensity as low as practical so that the trace is a thin curve O Adjust the vertical scale so that the waveform fills most of the display area o Use the GND coupling to adjust the zero then the AC or DC coupling to make the measurement O Adjust the horizontal position so that the peak or trough of the waveform coincides with the vertical line that has fine tick marks O Adjust the time scale so that the peak has an appropriate wid
39. OWER SUPPLY DATA SWITCHES x 5 ii Wr i i iri Prototyping Board eee eee ees ewe ee ee eee wee _ Put an alligator clip connector on each test lead of the multimeter Insert two wires into various holes in the prototyping board Checking for continuity convince yourself that the board is connected as shown below what it looks like from outside connections under the surface 13 9 Voltage Divider note no error measurements required for this part o A voltage divider reduces a voltage to a desired level Measure the values of the resistors shown in Figure 1 8 then wire up the circuit Use the prototyping board Use the 5 Volt power supply built into the prototyping board to supply Vin Figure 1 8 Voltage Divider a without load A Measure Vin and Vout for R1 3 2 k and R2 1 6 k Then repeat with R1 1 6 k and R2 3 2 k Compare Vout Vin to the predicted values b with load A Connect a 1 KO load resistor across the output Determine how much Vout is reduced loaded reporting the reduction of Vout as of the unloaded measurement of Vout Using the rules for parallel resistances compare to theory Note that while a voltage divider is easy to build it is a poor voltage source Its output is not stiff It is easily loaded 10 Potentiometer as a Voltage Divider no response needed for lab report Examining Figure 1 8 use the potentiom
40. P with some leads missing NC 5 joi Missing leads are indicated here as NC decimal left decimal 6 9 right decimal 8 d EE 128 7 Latch Used for Switch De Bouncing Note to instructor this circuit must be used with one of the counter circuits above It is possible to use either the binary counter or the decade counter An ordinary mechanical switch bounces several times when it opens or closes This means that it opens and closes several times on a time scale of about 100 us before reaching its final state When using a switch to input data to a logic circuit bounce is unfortunate because it looks like real data that is changing several times circuit intended to provide an output waveforms voltage vs input to a digital circuit time from switch 5 V what the switch does what it looks like to a digital input out what you really want a Bouncy switch _ amp Use a momentary contact switch not the switch built into your prototyping board it is already de bounced Use the multimeter to check continuity to see which two terminals to use on the switch so that it is normally open and closed only when you push Connect the simple input data switch shown below so that the switch is normally connected to LO Adjust a digital oscilloscope with DC coupling and approximately 100 usec div Observe the waveform of the output of the switch adjusting the trigger and timebase so that you ca
41. SOMETHING ELSE 4 Testing the circuit apply the states you predicted to the data inputs DO D7 and try all four combinations of inputs A and B Write your results in the form aof a truth table with three columns A B and Y State whether this truth table is the same as a two input XOR Repeat the previous two steps of predicting and testing this time for a 3 input XOR using A B and C as the inputs of the XOR 111 F mh Figure 8 1 Nand gate circuits 112 a b A 3 A B SS AB B B c d Figure 8 2 Circuits using NOR gates 113 QD Figure 8 3 Different realizations of XOR wD gt gt out C Figure 8 4 Half adder 114 Lab 9 Flip Flops Shift Registers Counters Decoders 7 Segment Display REFERENCE Horowitz and Hill Sections 8 16 8 26 Section 9 10 LED display Section 9 04 De bouncer INTRODUCTION In this lab we study two versions of the Flip Flop bistable multivibrator Then we test some counters and learn about BCD binary coded decimal Next we take the BCD output produced by the decade counter and convert it with a decoder driver to power a 7 segment LED display After building a counter we will use it to demonstrate how a switch de bouncer works Finally we try out a BCD to decimal converter You will look up a few items in data sheets to learn how to find information for chips EQUIPMENT Prototyping board Digital Oscilloscope Pulse Generator
42. Set the oscilloscope vertical voltage scales to be the same choosing a scale so that the trace fills a large portion of the screen If it fills only a small portion of the screen your measurements will not be very precise Use GND input coupling to find where zero volts is and use the vertical position to locate this on a gridline 28 If your function generator has a DC offset adjust it so that the bottom of the waveform is at zero volts Draw the oscilloscope display for the square wave and indicate the voltage at both the bottom and top of the waveform Adjust the oscilloscope horizontal time base so that the discharge time takes a considerable portion of the display Use the horizontal position to locate the waveform so that the triggering time is at a convenient gridline Your display should look like the figure above labeled charging Change the oscilloscope trigger slope between and to see the difference it makes a Charging amp Determine the charging time constant from the oscilloscope display Estimate your errors Calculate the ratio of your charging time to RC b Discharging Change the scope triggering slope to see the discharge portion of the trace Your display should look like the figure above labeled discharging Determine the discharging time constant from the oscilloscope display Estimate your errors Calculate the ratio of your discharging time to RC 29 Figure 2
43. T CH1 Volts Div 1 Volt use 1X indicator on dial input coupling DC CH2 same as CH1 INVERT switch set to the out position horizontal mode A time base A sec div 0 2 s VAR HOLDOFF NORM A TRIGGER P P AUTO LEVEL turn to about the middle SLOPE out A amp B INT CH1 A SOURCE EXT A EXT COUPLING DC Adjust the function generator settings to produce a sine wave with a frequency of about 100 Hz with DC offset turned OFF Learn the various vertical modes Try various settings of the vertical mode switches and see the display Use the BOTH mode on the vertical mode Compare ALT and CHOP You may need to adjust the beam intensity on the scope Change time base to 5 us observing the display Again compare ALT and CHOP You may be able to see the chopping of the signals in the chop mode Do you understand the difference between ALT and CHOP Learn how to use X Y mode First return the oscilloscope to the original settings Then set the time base to X Y Vary the CH1 and CH2 volts div and see how the display changes Make a Lissajous figure Connect a 8 V transformer to CH1 and a sine wave from the function generator to CH2 Adjust the frequency to multiples of 60 Hz while watching the display 33 Learn about trigger levels First return the oscilloscope to the original settings and set the time scale to 0 2 ms Change the cables to the function generator as shown in Figure 2 4 Adjust the function generator to pro
44. T V R Ry V R 1 Rz Rj V R forR lt lt Rj This is a crude current source because the current depends on the load resistance especially when R is not much less than R You will build a better current source using a transistor in Lab 4 Connect several different load resistances across the terminals and measure the current through the load resistor and the voltage across it in each case a What is the most accurate way for you to use a multimeter to measure current passing the current directly through the meter or using the meter to measure the voltage drop across a known resistance and computing the current from Ohm s Law b Make a table and or graph of current vs load resistance c Compliance Determine the range of load resistance over which the current remains constant to 10 Note In Lab 4 Junction Transistors you will need this result again 8 Learn how to use the prototyping board no response needed for lab report The prototyping board Prototyping boards are rows of connectors wired together behind a plastic face Things you can stick into the little holes of prototyping boards include wire 22 gauge solid core is typical resistor leads 1 4 or 1 8 Watt is typical leads for transistors capacitors diodes etc ICs the hole spacing is made for DIP dual inline package chips 12 LOGIC SWITCHES A LOGIC INDICATORS L1 L2 L3 La 5 j P
45. V t Vmax exp t RC for discharging Rules of thumb RC The product RC is called the RC time constant or simply the RC time When the input voltage of an R C circuit changes from one level to another the output voltage will approach its final value asymptotically RC is the time required for the output to swing by 63 toward its final value Because 1 exp 1 0 63 5RC is the time required to swing within 1 of the final value Because exp 5 0 007 1 27 voltage DISCHARGING Vmax 0 36 Vmax q Ro time voltage CHARGING lt _ RO time Measure the actual values of a 5 k resistor and an 0 003 uF capacitor Connect the series R C circuit to a function generator and an oscilloscope as shown in Figure2 3 a and 2 3 b This circuit is shown two ways to help you figure out how to wire it up Use a wooden board with binding posts Set the multimeter to measure frequency and connect it to the function generator Set the oscilloscope for external triggering EXT and connect the trigger input to the SYNC output of the function generator BNC connector labeled TTL CMOS see photo f Sync output Set the function generator to produce square waves with a peak to peak of function amplitude of about 5 Volts Set the frequency so that it is appropriate for generator measuring the time response of the R C circuit the period r 1 f should be 10 RC
46. after moving it from one oscilloscope to another Adjust the compensation on both of your 10X probes This requires a small screwdriver Verify that the probe s switch is in the 10X position Follow the steps of the 10X probe manual p 3 of the manual for the P2200 200 MHz Tektronix probe This procedure requires a square wave input use the two metal loop connectors labeled Probe Comp on the oscilloscope One connector is for the probe tip and the other for the probe s ground connector Set up the digital oscilloscope so that both the CH1 and CH2 menus are set for Probe 10X DC coupling BW Limit off Invert off 81 FA Identify the phototransistor and LED they look alike but the LED is much larger and the bumps on its leads are nearer its lens Identify the two leads of the phototransistor collector and emitter and the LED cathode and anode Discuss in one or two sentences why the phototransistor has no base lead Set up the pulser as shown in the photo except that you should use the following switch settings OUTPUT norm INT LOAD out PULSES DELAY doesn t matter PULSE norm Produce a square wave with an amplitude in the range 5 0 5 5 V peak to peak and a period of about 1 3 sec slow enough that you can see the LED blink when it is connected later Set Apply the TRIGGER OUTPUT of the pulser to the external trigger input of the scope Use the scope s trigger menu to choose norm
47. agram in the PRELAB Insert a large value resistor Ra typically 1 MQ in series with the function generator on the input of the amplifier as shown in Figure 4 7 1 MQ Oo _o to amplifier input Figure 4 7 Use the oscilloscope with AC input coupling to measure the output signal with and without the large input resistor Ra 5 Calculate the input impedance Rin If you measured hfe earlier compare your result for Rin to the formula given in the text p 66 Rin hfe 1 Rg c Output Impedance To measure an amplifier s output impedance you will connect a load resistor across the output Recall that when two resistances R Ro are connected in parallel the parallel resistance is Reff R1 R2 R1 R2 When the two resistances are identical Rj R2 R then Rep R 2 Now consider that a load resistance connected across the output of an amplifier is effectively a resistance in parallel with the output impedance of the amplifier If a fixed current i passes through the effective resistance the voltage drop across it as given by v i R will be reduced by half if R is reduced by half Set the decade box resistance R7 to the largest possible value Then connect the decade box across the output of the amplifier to serve as a load resistance as shown in Figure 4 8 66 12V VA i 10k 2N3904 1 uF Seri out 3 3 k R 12 Figure 4 8 Z Adjust the input signal to obtain a good sine wave on the o
48. al and external triggering Apply the OUTPUT across the LED and ground Hook up the circuit shown in the diagram Use a 270 Ohm resistor in series with the LED Use an emitter resistor Ri 1k on the phototransistor Use the bench power supply to provide 5 VDC for Vcc Connect the CH1 10X probe to the output of the pulser and the CH2 10X probe to the emitter of the phototransistor to observe its output Align the parts on your prototyping board so that the lens of the LED faces directly toward the lens of the phototransistor with a separation of about 1 cm Perform the following test to verify that the beam of light from the LED is pointed at the phototransistor Hold a piece of paper immediately in front of the phototransistor so that it blocks half the phototransistor s lens as shown in the photo which is best seen in color If the LED is aligned properly you will see half of a big red dot on the paper with the center of the red dot located at the center of the phototransistor s lens 82 ef FA LED facing the phototransistor at a distance of about 1 cm LED illuminates a spot of this size on the paper shown here with dashed lines Phototransistor facing the LED Paper blocking half the phototransistor s lens so that you can see where the light is Obtain an oscilloscope display similar to what is shown in the screenshot adjusting the horizontal position as necessary C
49. an 8 pin DIP op amp is shown in Figure 7 2 as viewed from the top offset null ne connected inverting input Vy non inverting input out V offset null op amp mini DIP package in most applications the offset null is not connected Figure 7 2 Op amp pin configuration 88 Note that an op amp is an active component that must be powered to work Most models need a bi polar power supply On a schematic diagram the power supply connections to an op amp are often not shown Connect the two terminals V and V_ to a 15 V power supply or 12 V on your prototyping board The prototyping board A prototyping board is made especially for DIP dual inline package ICs Many models have built in power supplies that you may use Use wires to connect the outputs of the 12 V power supply and ground three wires in all to a couple of narrow strips that look like 12 V fOoOOOOOOOODD GND DooooOoOoooood Insert the ICs carefully to avoid bending their leads into the wider strips like this 1 _Inverting amplifier To measure the amplitude of a sine wave measure peak to peak and divide by two Set up the oscilloscope to show a dual trace one for the input of the op amp and one for the output Use DC input coupling Set up the function generator to produce a sine wave with an amplitude 0 2 V and frequency 1 kHz Use the 20 dB button 89 on your function generator if necessary to reduce your func
50. ance of a digital multimeter is usually high enough several MQ that it has negligible effect on the circuit being measured Continuity check rc Many models allow you to check continuity emitting an audible beep so f that you don t need to look at the meter while making the test 1i Hooking up the meter Note that the meter is connected e in parallel to measure voltage or resistance e in series to measure current See the figures to see how this is done V Q Hz COM 20A A A 2A D gt Input jacks on a multimeter MAX INPUT N Hz 250V MA y 1000v UNFUSED 750V 10A cont es e Max 20A 30sec php NPN Fe gt LGE VQ gt TOM MAS 10A e A Ke DL KIT 27074 a Voltage V b Resistance 2 c Current A Multimeters The meter can measure voltage resistance and current Note two things e which connectors at the bottom are used e where the dial points your dial might look different from the one shown here but somewhere it will have V Q and A for measuring voltage resistance and current Q R Figure 1 4 Using a multimeter shown by Figure 1 3 Using a multimeter shown by Figure 1 5 Using a multimeter shown by the circle with a V to measure voltage the circle with a R to measure the circle with an to measure current resistance 1 DC voltage Set the function switch of the multimeter to DC volts with a scale commensurate with the volta
51. as a beta measurement feature use it to measure hfe Compute the following quantities i Predicted value of the dc base bias and the emitter potential assuming an 0 6V B E drop 74 ii Predicted value of the dc collector current and the dc bias on the output ii Compare the predicted value of the dc bias calculated in ii to 0 5 Vec Explain in terms of an undesirable circuit phenomenon that you wish to avoid why the value of the dc bias you predicted is desirable iii the impedance Zep of the emitter bypass i e the parallel sub circuit consisting of the emitter resistor Re amp the capacitor in series with resistor R3 for the following frequencies 0 100 Hz 5 kHz Recall that aresistor R3 and capacitor C that are connected in series have a combined impedance Zseries R3 Ze where Ze j C is the impedance of a capacitor at frequency w 2af a resistor Re in parallel with impedance Zseries has a total impedance 1 Zep 1 Re 1 Zseries Also recall that the magnitude of the resulting impedance is computed from its complex value as Z Z zy 2 iv the input impedance at 5 kHz if you didn t measure hfe assume it is 100 Note that resistors Ry and R92 appear to be in parallel with hfe times the emitter bypass Use the 5 kHz result see above for the emitter bypass impedance v the theoretical gain Ay Rc re Zep at f 5 kHz assuming re 25 Ic mA b
52. as for the CMOS chip For the remaining exercises you may use either TTL or CMOS 4 Quad 2 Input NOR 74LS02 or 74HC02 SN7402 N PACKAGE SN74LS02 SN74S02 D OR N PACKAGE TOP VIEW 1Y di UwOVvec FUNCTION TABLE each gate 1A 13N 4Y 1B 120 4B 2Y 119 4A 2A 10 3Y 28 g 3B GND a 3A a NOR Figure 8 2a b Inverter with NOR Figure 8 2b It is a useful exercise to look up the pin diagram in the data sheet in a data book This skill is necessary when you design a circuit yourself 108 c OR Figure 8 2c d AND Figure 8 2d See the pin diagram above amp Write down a Truth Table and check off every state as you test it Draw the gates 5 XOR 74LS86 or 74HC86 SN7486 N PACKAGE SN74LS86A SN74S86 D OR N PACKAGE TOP VIEW FUNCTION TABLE re Y L H H L Lo Ce Eat H H high level L low level a XOR from 7486 Figure 8 3a b XOR using NAND only Figure 8 3b See the pin diagram above amp Write down a Truth Table and check off every state as you test it Draw the gates ID Half Adder See Figure 8 4 Connect this circuit amp Write down a Truth Table and check off every state as you test it Draw the gates 1 151 Multiplexer A multiplexer is a switch It has multiple inputs and a single output The purpose of the multiplexer is to allow the user to determine which of the inputs should be connected to the
53. ator to signal input CH1 of the oscilloscope Set the function generator to produce a sine wave of about 1 to 2 Volt amplitude a frequency of about 100 Hz and no DC offset Verify that the 25 sweep INT EXT switch is in the EXT position to disable the sweep feature of this instrument Set a multimeter to the AC voltage function Connect it to the function generator s output Adjust the display intensity as low as practical so that the trace is a thin line Measure the peak to peak AC voltage using the oscilloscope Calculate the RMS value of the voltage Compare the AC voltage oscilloscope measurements to those on the digital multimeter Report the measurement uncertainty error values Which is more precise the meter or the oscilloscope c Sweeping the frequency no response necessary for lab report Learn to use the frequency sweep feature of your function generator Sweeping means that the frequency is ramped up with time in a way that repeats itself Observe this by depressing the INT button to enable the sweep Observe the waveform Try different adjustments of the TIME and WIDTH knobs for sweep to see their effect When you are done return the generator to its normal non sweep operation by pressing the INT button so that it is out not in d AC and DC coupling Make sure the oscilloscope coupling is set to DC Set the function generator frequency to about 10 kHz Turn on th
54. c of whatever you connect including components and any external instruments For this step the schematics should look like Fig 1 7 As you gain experience you will learn how to draw schematics without being shown an example to copy b Power supply A power supply is a voltage source powered by 110VAC You will use a bench power supply which has supplies an adjustable voltage A benchtop power supply typically has two knobs voltage and current The way it works is that only one knob will have an effect depending on two things the setting of the other knob and the load resistance For example if you turn the current knob up to its maximum value and if you use a large resistance for a load across the power supply outputs the voltage knob will be the one that has an effect while the current knob merely provides an upper limit to how high the current is allowed to go This will be how you will usually operate the power supply in this course An analog meter with a needle will have a measurement error due to your ability to read it Use your own judgment of what you think is a reasonable value for the error based on factors such as the width of the needle the spacing between tick marks and parallax due to viewing the meter with your head positioned at various angles Set the power supply to two different voltages and measure each of these Does the value on the power supply s meter agree with the value mea
55. cale factor e 0 5 C accuracy guaranteeable at 25 amp Use the LM35 Precision Centigrade Temperature Sensor chip which has a sensitivity 1 mV per degree C The diagrams below are from the datasheet for the LM35DZ Use a power supply voltage of Vs 5V First connect the sensor output to a digital multimeter and touch your finger to the sensor and observe the change in the output voltage Describe your observations Connect the sensor output to the input of the ADC circuit Can you observe a change in the data output in response to a change in temperature Discuss how you could use the ADC circuit to make a digital thermometer 145 V s 4V TO 20V OUTPUT ed O mW 10 0 mv G BS005516 3 FIGURE 1 Basic Centigrade Temperature Sensor 2 C to 150 C TO 92 Plastic Package BOTTOM VIEW LM35CZ LM35C AZ or LM35DZ 146 Lm35 Vour A1 Vs DS0055164 Choose Ry V50 pA V out 1 500 mV at 150 C 250 mV at 25 C 550 mV at 55 C FIGURE 2 Full Range Centigrade Temperature Sensor SPECIAL PROJECT Toward the end of the semester you will design and build a circuit of your own to meet whatever purpose you like Project planning This project is not like an ordinary lab assignment It is more like a part of a thesis project To be successful you must do project planning Project planning entails e making a schedule for yourself e allowing time to receive purchased supplies e a
56. cuit to save time If it is necessary to reduce the time further this zener diode section is the next choice for omission Zener diodes can be used as a simple voltage regulator to establish a reference voltage source for non critical applications CAUTION Zener diodes are very easy to burn up if you make a goof in wiring them up Remove the 3 terminal regulator and its accompanying two capacitors 53 Select an appropriate Zener depending on your transformer 5V for a 6 3 V transformer or 12 V for a 12 6 V transformer Assume the Zener has a power rating of 0 4 W in either case Add a Zener diode across the output of the PI filtered power supply you built in part 3b as shown in Figure 3 6 91 Q gt 100 uF 100 uF gt Figure 3 6 Pi filter with Zener diode voltage regulator a Calculations Before you power up your circuit do the following i Determine the maximum Zener current Iz ax from the power rating max ii Determine the total current through the 91 Q resistor lor Vin Vz 91 0 This current is the sum of the Zener current 7 7 and the load current 7 a Check whether it exceeds J because there must then be a minimum load current Z max to prevent overloading the Zener This will imply a maximum load resistance b Measurements i Output voltage Power up your circuit Measure the voltage across the load resistance 54 CAUTION in the next step to pr
57. duce a sine wave of about kHz Vary the trigger level and the trigger slope Observe the results Do you understand why the display depends as it does on these settings Change the trigger mode from AUTO to NORM Adjust the trigger level and or the function generator amplitude until you see that the oscilloscope no longer triggers Then adjust them back so that they do trigger Do you understand why the display depends on these parameters in the NORM trigger mode Return the oscilloscope triggering to AUTO before proceeding Learn how to use dual time bases Adjust the B Delay Time to zero or as near as possible Set the HORIZONTAL MODE to ALT Turn B Trigger level all the way to You should see an additional set of traces corresponding to A and B If not adjust A and B intensity or other settings until you do Turn A B SWP SEP to separate the two sets of traces Vary B Delay Time and observe the result Pull the DLY D SWEEP knob and adjust delayed sweep time scale to 20 us Observe the effect on the display Note the de intensified display of A this shows the portion of the A trace that is represented by the B trace Change the function generator to produce a square wave at 1 MHz Set the oscilloscope to A sec div 5 us B sec div 05 us tT Some models such as Tektronix 2235 have a delayed sweep feature required for this step while others do not If your scope doesn t have this feature and
58. e 12 Volt power supply that is built into your prototyping board or an external power supply set to about 10 V 5 V output 4 7 uF to guard against oscillations Z Confirm that the output is 5 Volts 0 01 uF to provide short term smoothing An ideal voltage regulator supplies the same output voltage e regardless of the input voltage as in test c below e regardless of the output load as in test d below b Use as a power supply regulator Now connect the input of the 78L05 regulator as shown below to the output of the power supply you built in step 3 Include a 1 kQ load resistor 51 5 V output 0 01 uF RL J filter 3 terminal capacitor regulator Turn on the power supply and observe the output voltage 4 Compare to the filtered output without regulation as measured in step 2 c Regulation as the input voltage is varied Now plug the transformer of your power supply into a variac instead of into 110 VAC Connect a multimeter to measure the Volts ac from the variac Set Rz to 1 kQ Adjust the variac output voltage beginning at110 VAC and going downward using the printed scale on the top of the variac Caution Do not operate the variac at voltages above 110 V Variac Confirm that the regulator maintains the same 5 Volt output over a wide range of AC voltage typically from 80 to 110 VAC d Regulation as the load is varied Disconnect th
59. e SCSI RC CEER SAIC ACER CEES SS TERT AEE Ck we doe a EEN e veeaeveeveaceec Dem eea Di 2 OCC CERES ECA SPER FP 8 8 8 eereteeacedene 6 8 6 6 6 66 6 6 6 ee 6 Ege ee Pe Re e a 6a a se oe ee A d CN HON MEASURE CH1 Pk Pk 3 204 CH2 Pk Pk 3 004 CH1 Freq rd CH1 Rise Time 33 20ns CH2 Rise Time 6 170 us CH1 2 00 CH2 100 8 M5 00us CH1 3 04 Lab 7 Operational Amplifiers Op amps REFERENCE Horowitz and Hill Sections 4 01 4 09 4 11 Appendix K 411 datasheet INTRODUCTION The operational amplifier op amp is an integrated circuit i e chip is a multistage transistor amplifier with a differential input has a high input impedance 1012 Q for J FET input op amps is usually used with an external feedback network can amplify or perform mathematical and logical operations can operate from DC to MHz frequencies depending on the op amp model requires bi polar power supply typically 15 V The comparator is similar to an op amp but it is used for a different application its output swings from one rail to the other depending on which of the two inputs is more positive Note The student will need software to make graphs EQUIPMENT Prototyping board Digital Oscilloscope Function generator Digital Multimeter Op amp 2 LF411CN or equivalent 8 pin DIP Comparator LM311N Resistors 1k 2 10k 4 22 k 100 k 5 M 47k D
60. e function generator to apply a sine wave of approximately 1 2 1 8 volts amplitude and approximately 1 kHz frequency to one of the oscilloscope inputs Using the MEASURE button measure the amplitude and period of the waveform Compute the uncertainty of the amplitude and the uncertainty of the period Do this using specifications from the oscilloscope s manufacturer s user manual For the TEDS 1000 or 2000 seies oscilloscope see pp 155 156 To compute the uncertainty of the period you will require the sampling period which is the reciprocal of the sampling rate this parameter depends on the tim div setting see the table on pp 22 23 Note this exercise is intended to train you to look up manufacturer s specifications for an instrument which is a routine all physics experimenters should follow in their research 45 Diode Limiter Diode limiters could be used at the inputs of small signal instruments to protect against accidental application of large input signals This is a low current application so you use signal diodes not current diodes Using signal diodes connect the input of the circuit shown below to the function generator set to about 1 kHz Check that the 20 dB attenuator switch on the function generator is not activated Try sines triangles and square waves of various amplitudes Try a low amplitude for the oscillation and adjust the function generator s dc offset to observe the effect
61. e grounds if desired to reduce noise Here we will not use this feature The purpose of C2 is merely to reduce noise in the voltage divider s output it is not a critical component 144 5 Using sensors There are several ways to detect temperature As is often the case a specialized integrated circuit is a good solution Here you will test the LM35DZ General Description from the National Semiconductor datasheet The LM35 series are precision integrated circuit temperature sensors whose output voltage is linearly proportional to the Celsius Centigrade temperature The LM35 thus has an advantage over linear temperature sensors calibrated in Kelvin as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling The LM35 does not require any external calibration or trimming to provide typical accuracies of 1 4 C at room temperature and 34 C over a full 55 to 150 C temperature range Low cost is assured by trimming and calibration at the wafer level The LM35 s low output impedance linear output and precise inherent calibration make interfacing to readout or control circuitry especially easy It can be used with single power supplies or with plus and minus supplies As it draws only 60 pA from its supply it has very low self heating less than 0 1 C in still air Features e Calibrated directly in Celsius Centigrade e Linear 10 0 mV C s
62. e offset voltage on the function generator and twiddle the offset up and down You should see a vertical deflection of the trace Now change the oscilloscope coupling to AC and twiddle the offset voltage slowly You should see no change Explain the difference between AC and DC coupling Through what additional component inside the oscilloscope does the signal pass when using AC coupling 2 Measurement of Frequency 26 Use the same set up as above Use a digital multimeter to measure the frequency connecting the multimeter to the function generator s SYNC output which might be labeled TTL depending on the model of the function generator Determine the frequency from the measured time per cycle Repeat for five frequencies in total over the entire s i ync output range of the function generator of function generator Make a table to compare the frequency measurements made with the oscilloscope to those with the digital multimeter Include columns for the measurement uncertainty error values Which is more accurate the meter or the oscilloscope As a practice never trust the frequency and voltage readings shown on a function generator Always make external measurements of the frequency and voltage For the remainder of this experiment use the multimeter for your frequency measurements Time Constant of an R C Circuit The output voltage of an RC filter is V t Vmax 1 exp t RC for charging
63. e sure to use DC coupling on your oscilloscope input c Frequency response Vary the frequency while observing the input and output waveforms on the oscilloscope It is not necessary to record data for this step Discuss in one sentence how your observations are consistent with the description low pass filter R2 5 MQ C 0 01 uF R1 10k out Figure 7 7 Op Amp Integrator 95 __Differentiator high pass filter The configuration in Figure 7 8 with the main components C1 and R2 is a differentiator Differentiators always have difficulty with high frequency noise so a low pass filter combination C2 and R4 is added to reduce the noise Connect the circuit shown in Figure 7 8 and apply a sine wave to the input If the output of the circuit exhibits clipping reduce the input amplitude if turning the function generator s amplitude knob isn t sufficient see if your function generator has an attenuation button which might be labeled 20 dB for example a Differentiation Print the outputs of the differentiator circuit for a sine wave and a ramp wave inputs at a frequency 100 Hz Explain how your waveforms are consistent with the circuit taking the derivative of the input b Frequency response For a sine wave input vary the frequency while observing the input and output waveforms on the oscilloscope It is not necessary to record data for this step Discuss in one sentence how your ob
64. e variac Connect your multimeter to measure current through the load CAUTION In this step to protect the decade box always keep 50 or 100 Q switched in while you adjust the other scales This precaution will keep you from accidentally setting the decade box to zero resistance CAUTION As always measure current beginning with the meter set to the highest scale Set R to about 10 kQ and vary it downward 52 ea fA TO 92 package TO 220 package ZA Note the load resistance at which ripple begins to appear What current value does this correspond to This is the maximum regulated current e Thermal protection Z Continue to decrease the load resistance Does the output of the regulator shut down when the current exceeds a certain threshold This is the current limit of your regulator To work this shut down test requires using a regulator in the TO 92 package don t use a larger package like TO 220 LM78MO05CT for this lab it won t shut down under these conditions An advantage of these three terminal regulators is the shutdown feature Another alternative for voltage regulation is the zener diode in the next experiment but zeners do not have thermal protection so you must be careful to select the right one and use it within its design parameters 6 Voltage Regulation with Zener Diodes TA note usually there is enough time to do all of this lab except that some instructors omit the SCR cir
65. ecade box Capacitor 0 01 uF 50 pF Potentiometer with wires soldered on preferably 50 k Photocell NSL 4522 86 PRELAB 1 Identify all the formulas you will need in this Lab 2 In this lab you will use decibels or dB This is a dimensionless ratio in logarithmic form The formula is Xas 20 logio X where X is any dimensionless ratio For example X might be the gain A of an amplifier If the gain A of an amplifier is 100 you can also say that the amplifier has a gain of 40 dB Note that negative values correspond to a ratio of less than unity for example an amplifier with a gain of 0 01 has a gain of 40 dB You can compute a voltage ratio by taking the exponent of 10 for example the voltage ratio corresponding to a gain of 15 dB is 10 15 20 5 623 Calculate the following a The gain in dB of an amplifier with a gain of 10 000 b The gain in dB of an amplifier with a gain of 0 1 c The voltage ratio that corresponds to 3 dB 87 PROCEDURE 0 Things to know non inverting input out inverting input Figure 7 1 Symbolic representation of an operational amplifier An op amp ideally obeys the rules 1 The output voltage does whatever necessary to make the two inputs at the same voltage 2 The current drawn by the two inputs is zero Also an external feedback network must be provided that connects the output to the inverting input this provides negative feedback The pin configuration for
66. en response required Connect a scope probe to the digital oscilloscope as shown in the photos below A scope probe has two settings 1X and 10X photo shows 10X setting This notation might be confusing the 10X setting has the effect of dividing not multiplying the signal by a factor of ten An advantage of a 10X probe is that it has a higher frequency response so that if you need to view signals gt 1MHz you should use a 10X probe In most of this course you will view slower signals and a 1X probe is adequate 43 Tirg d Indicates the scope is triggering amp updating its display Arrow indicates Zero voltage level for Channel 1 Indicates trigger level Mean 251 Frea 1 000kH2 Gi T Aa lt SAAN hvvwwwwn its Volt per division Time per division horizontal vertical Press the AUTOSET button to see the display of a square wave Push the CH2 MENU button twice to see how this turns the display for that channel off and on The two channels are distinguished by their color To see their effect adjust these knobs VOLTS DIV SEC DIV VERTICAL POSITION HORIZONTAL 7 TS POSITION Look for the arrow at the top that indicates the Coupling trigger time and the arrow at the right that indicates zero OL voltage BY Limit Off Push the CH1 MENU button to see the display Toggle the AN Probe setting so that it indicates the same setting as on your probe 1X not 10X or 100X
67. er your basic circuit is tested successfully extra features such 148 as displays or adjustable settings can be added Do this if your basic circuit idea does not have enough components Purchasing e Buy from local sources wherever possible e Plan well ahead if you buy by mail e Buy several spares for every semiconductor chip or high power item e Obtain data sheets for all semiconductors and chips Testing tips e Begin by testing your circuit one section at a time on a prototype board Don t assemble a big circuit all at once and expect it to work You will have bugs to work out and this is easiest to do if you assemble it in stages one section at a time e Use an oscilloscope to observe AC signals in an analog circuit If you wish you may test your design on a computer using Spice based circuit simulation software such as Multisym before you build it e Buy a small prototyping board of your own so that you can keep your project assembled as you work on it Otherwise you will have to disassemble it so that other students can use your board A single strip or two may be enough e If your circuit s inputs are to come from a transient source such as pushbuttons or random pulses test your circuit with a repetitive waveform from a function generator Power supply tips e If your circuit consumes more than 100 mA from a 5 VDC power supply use a bench power supply HP or Lambda for example instead of the prototypin
68. esistance function Never connect the multimeter to a resistor that is part of a circuit Use it only to measure the value of a loose resistor 6 Current a Measured values 560 Measure the actual value of the resistor shown in i Fig 1 8 Throughout this course always measure your Tey resistor values before assembling the circuit b Comparison to predicted values Figure 1 8 Wire up the circuit in Figure 1 8 Set the function switch to the maximum current scale 2 A and connect the meter into the circuit 66 Note that for current measurements the meter is in series with the other elements of the circuit This is different from voltage measurements where it is in parallel 4 Compare the measured value with the value of current you would calculate using the measured values of voltage and resistance Do they agree within the error value range Explain any discrepancy 7 Current Source Connect a 1 5 V battery and a large valued resistor 10 KQ or higher to make a current source For a load resistor use the decade box choosing values ranging from 0 1 to 2 0 times the value of the large resistor as shown in Figure 1 7 11 large value resistor 15V Figure 1 7 i load resistor Testing a current source This combination of a battery in series with a large resistor will act as a current source provided the load resistance connected to the terminals is small The current is I
69. eter instead of fixed resistors to hook up the circuit Be sure that you apply the input voltage across the two terminals that have a fixed resistance The wiper of the potentiometer should be the output terminal in the middle right of Figure 1 8 Observe the output voltage while turning the potentiometer If the output voltage increases as you turn the knob clockwise you are done otherwise change one of the output connections 14 Lab 2 AC Measurements REFERENCE Horowitz and Hill Sections 1 13 1 18 1 19 Appendix A Oscilloscope INTRODUCTION The object of this lab is to learn measurement skills You will become familiar with the oscilloscope function generator and pulse generator in measuring time varying electrical signals You will measure e DC and AC voltages e Frequency e Phase e Time constant of an RC circuit e Amplitude and phase shift responses of low pass and high pass RC filters EQUIPMENT Analog Oscilloscope Tektronix 2235 or equivalent Function generator BK 4017 Pulse generator HP 8013B DC power supply Multimeter handheld Multimeter Agilent 34410A 8 V transformer Resistors 5k Capacitors 0 003 uF BNC cables BNC TEE BNC banana adapter wooden board with binding posts BNC TEE BNC banana use computer to plot graphs adapter use graph paper at end of this manual to draw waveforms a sd BNC cable Copyright 2010 John A Goree Edited by John Goree 11 Ja
70. function is usually defined for only two inputs Sometimes the term is used for a three input device when this is done it is usually a parity generator which outputs a true 1 signal if an odd number of inputs are true and a false 0 signal if an even number of inputs are true The reason this device is sometimes called a three input exclusive or is that it can be built from combing a pair of two input XOR gates applying their inputs to an OR gate which then generates the final output 3 Refer to a textbook e g Horowitz Hill p 495 for a description of a multiplexer Learn how the address bits are used to select which of several inputs is sent to the multiplexer s output Explanation added 2010 103 PROCEDURE 0 Things to know About digital inputs In making tests you will need to connect some inputs to your digital circuits For a LO input use a wire between the digital input and ground For a HI input use a 1 k resistor between a digital input and 5 V An alternative method more convenient than using resistors as described above requires using a prototyping board that has built in switches for logical HI and LO y z 3 b inputs These provide suitable inputs for logic circuits and sw1 swe sw3 sw4 don t require resistors DATA SWITCHES On your prototyping board Use two wires to connect the 5 V and GND outputs of the power supply to a strip that looks like SSS OS SS
71. g board Otherwise your circuit will stop working due to loading the power supply which will result in the power supply voltage being too low to operate your circuit e Some circuits that involve large currents that are not DC currents for example an LED display or a 555 timer that has a large value for the external capacitor will cause the power supply voltage to droop momentarily and this can cause errors in logic chips elsewhere in the circuit To avoid this place an electrolytic capacitor a few microfarads across the power supply leads on your prototyping board and locate this capacitor physically near the subcircuit such as a 555 timer or LED display that is demanding a large current e Ifyou use a 9 Volt battery you can reduce the voltage to 5 VDC using the 3 pin voltage regulator from one of the labs in this manual 149 Special Project Grading At the end of your project you will e Present a schematic diagram label every part identify function of switches etc e g reset power e Present a list of specifications at least 3 numbers example frequency bandwidth Hz 3 dB flatness max input voltage V input impedance W identify whether measured or computed measured is better include error estimate and units e Demonstrate how your circuit works plan how to show it in 5 minutes in case it doesn t entirely work demonstrate that part of it works hope for partial credit for the part that does wor
72. g change in digital output voltage using a 250 nsec div on the oscilloscope s horizontal scale amp Record the oscilloscope display showing the ringing or oscillations present in the digital output with a typical characteristic time of 200 nsec Now connect a 100k resistor between output pin 7 and the non inverting input pin 2 of the comparator This provides positive feedback Record the waveform Discuss whether the undesired oscillations are diminished by using positive feedback and if so whether the effect is a strong one 8 Using sensors TA may omit this procedure if time does not allow it 66 There are several ways to detect light Here you will use a photocell which is a simple two terminal sensor that acts like a resistor with a resistance that diminishes as the light level is increased It is not a linear sensor so its use if often limited to electric eye applications that require detecting whether conditions are light are dark for example to turn street lights on and off If you needed to measure light intensity over a continuous scale you would choose a different sensor one that has a linear response to light intensity NSL 4522 CdS Photocell specifications from Silonex datasheet Rdark min 1 M minimum R 1 foot candle 18 6 k 40 R 100 foot candle 400 typical 98 Design a simple voltage divider to replace the function generator in the comparator circuit above
73. ges expected in the circuit To protect the meter from damage ALWAYS SELECT THE MAXIMUM VOLTAGE SCALE TO START WITH Then adjust the scale downward until a meaningful reading is obtained a Batteries in series amp Measure the individual voltages V1 and V2 of two 1 5 V batteries amp Then connect the batteries in series with forward polarity as shown in Fig 1 7 and measure the total voltage yet Provide an uncertainty for this measurement based on the multimeter s specifications 1 5V 1 5V battery battery _ multi meter 1 5V 15V 7 a battery battery 7 Figure 1 7 Figure 1 6 Two batteries connected in series with forward Board with two batteries polarity left and reverse right A Reverse the polarity of one of the batteries and measure the total voltage V meas Provide an uncertainty for this measurement based on the multimeter s specifications amp Calculate the expected results Vaie V1 V2 and V catc V 1 V2 for forward and reverse polarity of the two batteries Note that these are calculated quantities not measured quantities so that their uncertainty must be calculated using propagation of errors Perform this uncertainty calculation yielding SV fak and 8V calc Compare these expected results Vate SVicate and Vicar SV calc to the corresponding measured values yf mas tO Vf neas and ae 6 Vf ncas In both your notebook and lab report you must always draw a schemati
74. he 74LS161 to switches on the prototyping board and the outputs to LED s as follows INPUTS OUTPUTS binary 23 22 21 20 23 22 21 20 state IND IN INB INa LOAD QD Qc QB Qa IC pin 6 5 4 3 9 Ti 13 13 14 board SW1 SW2 SW3 SW4 SWA LED1 LED2 LED3 LED4 Connect pin 2 CLK to a 1 Hz clock on your prototyping board Set the following pins on the 74LS161 to HI you may use data input switch on your prototyping board to accomplish this Enable P pin 7 Enable T pin 10 Clear pin 1 123 When LOAD pin 9 is LO the counter can be loaded with a binary number on data inputs INp INC INB INA When it is HI clock signals are counted Before using the circuit convert the decimal number 12 to binary Program the counter so that it will count from 12 Do this as follows With LOAD LO input the decimal number 12 on the input switches Then set LOAD to HI Now clock the CLK input and watch the chip count in binary from 0 to 15 Note that it will start at the value 12 that you programmed then count up to 15 then start over at 0 Draw a timing diagram for the counting showing CLK and outputs QA QB QC QD 4 Decade Counter 7490 66 Referring to the diagrams below from the data sheet we see that the 90 has four internal Flip Flops The first one is not internally connected to the others while the other three are cascaded to form a divide by 5 synchronous counter LOGI
75. he pulse input to the 5 input Print the waveforms Explain how the waveform is divided by five Note the asymmetry of the output waveform c Divide by 10 125 Connect the 5 output to the 2 input Use the scope to observe the 2 output amp Print the waveform Discuss briefly the meaning of the phrase divided by ten as it is shown by your waveforms identifying which parameter is divided d BCD Counting Binary coded decimal BCD is the same as binary for numbers 0 to 9 For larger numbers it is different BCD is composed of groups of four binary digits where each group represents one digit in base 10 Example 314 decimal 3 1 4 BCD 0011 0001 0100 binary 100111010 For this chip outputs QA QB QC and Qp are the four bit BCD outputs Disconnect the pulse generator Use a switch on your prototyping board SWA to apply a pulse input on pin 14 Connect Qa pin 12 to the 5 input pin 1 for BCD counting It may already be connected this way from part c above By means of LED indicator lights you may use those built into the prototyping board test the levels of the D C B and A outputs pins 11 8 9 12 respectively after each pulse i counting amp Write a copy of Table 9 1 and check off each state 0 through 9 to confirm that the outputs D C B and A of the counter accumulate in a BCD counting cycle Note the output may at first indicate an invalid number such as 1
76. heck that that the signal disappears when you insert a piece of paper between the LED and the phototransistor to fully block the light Press the measure button on the scope and set it to measure Pk Pk and rise time as shown in the screen shot below Without disturbing the LED or phototransistor determine the criterion used by the oscilloscope to measure the rise time Do this by measuring the waveform yourself Measure three voltages Vo before the rise V after the rise is complete and V at the time indicated by the scope as the measured rise time Hint Remember the skills you learned when using the analog scope manual measurements are easiest if you make use of the major division lines on the scope display Adjust the horizontal position or trigger delay so that the pulse begins on a major division on the time scale Adjust the vertical position so that the baseline for the pulse is similarly on a major division line Adjust the pulse amplitude so that the phototransistor output varies an integer number of divisions Choose appropriate scales for the vertical and horizontal axes so that the interesting part of the waveform fills a large fraction of the display Print out your oscilloscope display resembling the screenshot shown here Record the value of rise time indicated by the oscilloscope 83 Compute the ratio V Vo V Vo expressing your answer as a percentage i e XX This result should be the same
77. ired in a box with a battery or power supply If your final project is built on a prototype board it must be more ambitious If it is hardwired in a box it must meet good standards for safety and quality of construction Hardwired projects Safety use a grounded box use grommets amp strain relief for power cord cover all 110 VAC so that it is unreachable when the box is closed Connectors use a terminal strip with crimp on lugs for 110 VAC Holes de burr holes after drilling sheet metal Wires to front panel bundle them with tie wraps for neatness Circuit boards line up ICs and other parts in neat rows don t cross wires over chips use sockets for chips Testing test your ideas on prototype boards first show the instructor that your prototype board version works for partial credit in case your final circuit doesn t work Special Project Tips Planning As with all research projects e Plan ahead e Procrastinators will learn a hard lesson e Expect your project to require 3x as long as you expect e Expect things to go wrong Designing e A simple idea that works is better than a grand idea that fails e Avoid designing circuits with high speed high frequency high voltage or high current e Design a circuit mainly or entirely based on components that you already understand like op amps and digital gates e Many successful projects begin with a fairly simple idea then add bells and whistles Aft
78. itting diodes HLMP C115 obsolescent this LED chosen for its 30 nsec response Red diffused LED NPN Phototransistor Panasonic PNA 1801L Small screwdriver to adjust the 10X probe 00 20 20 NOT Unit mm 0 197 0 008 OTE Y amp 71 20 20 1 14 20 20 0 243 s 0 008 0 045 2 0 008 1 85 0 073 MAX Not soldered 2 0 max 0 70 0 028 MAX 15 0 1 0 0 50 0 10 1 00 0 TYP 0 0 MIN 0 020 0 004 0 5 0 1 5 40 20 20 0 228 2 0 006 lt 0 100 2 0 015 ot iN HEHEH NOTES C 1 ALL DIMENSIONS ARE IN MILLIMETERS INCHES l Emitter 2 LEADS ARE MILD STEEL SOLDER DIPPED 2 Collector 2 AN EPOXY MENISCUS MAY EXTEND ABOUT 5 xen 0 020 in DOWN THE LEADS HLMP Cx15 and HLMP Cx23 LED HLMP C115 NPN Phototransistor PNA1801L Note the flat edge of rim Note emitter pin is longer indicates cathode 79 PRELAB 1 Identify all the formulas you will need in this Lab 80 PROCEDURE 1 Adjust 10X probe compensation As you previously learned in Lab 3 a 10X passive prove attenuates a voltage by a factor of 10 so that an oscilloscope measures one tenth the original voltage It is preferred over a 1X probe for high frequencies gt 1 MHz and therefore it is used whenever one needs to measure fast rise times lt a few microseconds Due to variations in oscilloscope input capacitances it is necessary to adjust a compensation trimmer on a 210X probe
79. k Here is a grading scheme that your instructor might use grading factor prototype hardwired design 80 60 cleverness of idea how well it works how ambitious it is schematic diagram 10 10 specifications 10 10 quality of construction 15 safety 5 For error estimates for values measured using a digital oscilloscope or other instrument see the specifications for accuracy in the manufacturer s User Manual For the multimeter this table is reproduced in the preface to this manual for other instruments you should refer to the actual manufacturer s User Manual 150
80. llowing time to assemble test and debug your experiment and finish it on time e budgeting for costs An original idea The circuit you design may be analog digital or both The circuit could arise from your thesis project or it could complement an existing instrument for example your telephone or stereo You could make a game a circuit that demonstrates some mathematical or scientific concept or something for a hobby such as a temperature controller for a photographic darkroom It is up to your imagination Warning Your design must be your own Be prepared to identify which portion of your circuit is your idea and which portion is copied from another source Students who are unimaginative and copy entire designs from books the internet or someone they know are usually unable to answer questions about their project at the time it is graded and they receive a poor grade Requirements Your circuit must include a minimum number of electronic components that will be agreed upon when you discuss your ideas with the instructor Money Purchase your own components from vendors such as the following e UI Engineering Electronics Shop http www icaen uiowa edu eshop e Radio Shack e DigiKey tel 1 800 DIGIKEY http www digikey com Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 Two ways to build You must choose either to a build it on a prototype board and disassemble it afterwards or b to build it hardw
81. lso show on this graph the theoretical gain Ay Ro Rj Note that high gain is achieved at the expense of frequency bandwidth Voltage Follower Unity Gain Non Inverting Amp 66 The circuit in Figure 7 4 has a voltage gain of unity but a very high current gain a Input impedance 4 Use a5 MQ resistor in series with the function generator at the input to measure the input impedance If it is too high to measure report it as Zin gt gt 5 MQ out 5 MQ source for measuring Zin voltage follower Figure 7 4 Unity gain non inverting amplifier Voltage Follower 91 3 Summing Amp Build the circuit shown in Figure 7 5 Choose R1 10 k 10 k WwW R1 in 2 out Figure 7 5 Summing Amplifier Use a 4 Volt P P sine wave for input 1 Use a 5 V dc voltage from a power supply your prototyping board is ok for input 2 Connect the oscilloscope using DC input coupling to monitor input 1 and the output a Summing Confirm that the output is minus the sum of the inputs Sketch or print the waveforms and mark values at the following phases of the sine wave peak trough and zero Also present calculations showing that the output is approximately equal to the expected value of the sum of the inputs do this for three cases corresponding to the three phases peak trough and zero b Clipping Use the DC offset on your function generator to raise the dc input voltage until you see a pronounced clip
82. lues from part a and compare with your measurements including error values calculated using propagation of errors 4 Potentiometer no response needed for lab report The potentiometer has three terminals two are the ends of a fixed resistor and one is the wiper Using the two leads of the multimeter to test different pairs of the potentiometer terminals and by turning the potentiometer while observing the resistatance a determine which terminal is the wiper and b verify that the resistance between the other two terminals does not vary as the potentiometer is turned Determine which pair of terminals has a resistance that increases when you turn the potentiometer clockwise as viewed from the top 5 Continuity no response needed for lab report With the function switch set to Ohms touch the two test leads together while watching the display Now set the function switch to continuity Depending on your multimeter this might be indicated with a symbol like this Touch the two test leads together and listen for the beep This is one of two instances in this lab where you are asked to use propagation of errors 10 Caution Avoid damaging your multimeter In the current function Never connect a current meter directly to a voltage source like 110 VAC or a battery Without a resistor to limit the current this would destroy the meter or at least blow a fuse inside the meter In the r
83. mAde Ip 15 mAdec lc 500 mAde Ip 50 mAdc Base Emitter Saturation Voltage VBE cat Ip 150 mAde Ip 15 mAde Ig 500 mAde Ig 50 mAdc A BASIC FACT TO KNOW In electronics e It is USUALLY OK to connect an output of a circuit to the inputs of two circuits e Itis NEVER OK to connect two outputs together 59 PRELAB 1 Identify all the formulas you will need in this Lab 2 In this lab we will use a method of measuring the input impedance Zin of a circuit This impedance will be purely resistive because the circuit will have no significant capacitance or inductance The scheme is to connect a large input resistor Ra in series with the circuit s input and measure the resulting decrease in the circuit s output You can think of Ra and the circuit s input impedance as being like two resistors in series i e a voltage divider See the diagram below the circuit which has a gain Ay is shown as a box with an input and an output a Derive a formula for Zin as a function of Ra Vose Wout and the gain Ay b Write a simplified version of this formula valid for Ay 1 c Write an even more simplified version valid if Ay 1 and Vou Vossel 2 Circuit Ra setup Vosc measure Vout here pen Conceptual Vose equivalent circuit measure gt Vout Zin here 60 PROCEDURE C C Figure 4 1 B B as l E E NPN PNP 2N2222 Figure 4 2 NPN Transistor pinouts i Examples C 2N2222
84. mation or spending too much time on unnecessary efforts in writing the report Lab 1 DC Measurements REFERENCE Horowitz and Hill Sections 1 01 1 05 Appendix C Resistor color code Appendix E How to draw schematic diagrams INTRODUCTION This experiment has the following objectives Become familiar with multimeter prototyping board resistor color code reading a schematic diagram wiring a circuit Study a current source A voltage source Figure 1 1 such as a battery or power supply is inherently a device with a low internal resistance It should provide a constant voltage for a wide range of currents A current source Figure 1 2 on the other hand should provide a constant current to a wide range of load resistances Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 FLL 96 Figure 1 1 Figure 1 2 Voltage source Current source series AA A AN A Rseries R1 R2 parallel Series and parallel circuits Study a voltage divider A voltage divider is two resistors connected in series voltage divider Vout Vin R2 R1 R2 EQUIPMENT Digital multimeter BK Model 388 HD Battery LSV 2 Battery weak 1 5 V marked X or weak DC power supply Resistors 100 560 1 k 1 8 k 3 2 k 50k Box of assorted of resistors Potentiometer with wires soldered on preferably gt 1k Decade box with 1000 Q decade or higher for top decade 8 V transformer TA note b
85. mns for f Az error bar for f delay in msec error bar for delay in msec phase in degrees error bar for phase in degrees ii Plot the phase curve on a graph with a semi log scale linear flog Compare with a theoretical plot of the phase shift on the same graph iii What is the phase angle measured and theoretical at f 1 2 RC 31 5 _R C High Pass Filter Use the same 5 KQ resistor and 0 003 uF capacitor as in the R C low pass filter above but swap them to make a high pass filter 0 003 u 5k Vout High Pass Filter Instead of the analog oscilloscope use the Agilent 34410A multimeter to measure the input voltage rms and output voltage rms Make the amplitude response measurements and plots omit the error values Use the following frequencies 100 kHz 50 20 10 3 1 0 3 0 1 kHz also include a frequency of f 1 22RC in this sequence as calculated from measured values of R and C 6 Measurement skills no response necessary for lab report Use your remaining time in the lab session to familiarize yourself with the oscilloscope and pulse generator Connect the function generator to the oscilloscope as shown in Figure 2 4 Ll _ CH1 CH2 EXT SYNC OUT OUTPUT FUNCTION GENERATOR or PULSE GENERATOR Figure 2 4 32 Ca Cm Adjust the oscilloscope settings to the following settings hereafter referred to as the original settings Vertical mode BOTH and AL
86. n 2010 ABOUT ANALOG OSCILLOSCOPES The heart of an analog oscilloscope is its cathode ray tube see Figure 2 1la An electron gun produces a beam of electrons that strikes the screen making a visible spot The beam is deflected by two pairs of deflection plates A sawtooth time base voltage is supplied internally to the horizontal deflection plates to sweep the beam linearly with time across the screen horizontally The voltage to be observed is supplied to the vertical deflection plates The result is a picture of the signal voltage versus time Electron Gun Vertical Input Signal Horizontal Input Time Base Sawtooth Figure 2 1 16 ABOUT TRIGGERING Triggering of an oscilloscope is often confusing for beginners A trigger is an event that starts the horizontal sweep or trace see Figure 2 1b This trigger event is defined by comparing two voltages the moment when the trigger source voltage exceeds the trigger level voltage is the trigger event The trigger source can be e an external voltage EXT that you connect to the oscilloscope e or it can be one of the vertical inputs CH1 or CH2 Usually you must choose between AUTO and NORM triggering e NORM triggering will allow a trigger only if there is a trigger event e AUTO triggering will cause a trigger even if there is never a trigger event the beginner will usually use this setting since it always yields a display voltage trigger
87. n see any bounce as in the photo below 129 5V Apply the output to the clock input of a counter circuit you may use any of the counter circuits you built above amp Press the switch watch an LED indicator of the counter output Does the counter count more than one clock due to bounce amp Observe and print the waveform produced by the switch Use a digital storage oscilloscope digital scope counter push button switch is normally closed but open when pushed Tek SL Denier TET ee Tey 19 CHT 2 00 130 a E Ready M Pos 144 0ns CH1 D Hab RB chibi TER Coupling DC Bw Limit MHZ Volts Div Coarse Probe Invert Off Middus CHT Dv b De bounced switch The circuit shown below is called an SR flip flop or a cross coupled NAND latch Wire it up using a 7400 quad NAND gate chip Now add a switch with pull up resistors to make a data input as shown below Press the switch and observe that the counter counts only one clock because the switch is now de bounced 5V counter 5V 131 The 042 BCD to Decimal Decoder Chip Before wiring the circuit convert the following decimal numbers to BCD O 1 8 Wire the decoder chip with four inputs for BCD input Use the switches on your prototyping board to provide input as shown below BCD INPUTS binary 23 22 21 20 state D B A IC pin 12 13 14 15 board SW1 SW2 SW3 Sw4
88. n the preceding experiment In the common emitter amplifier experiment you will learn techniques and terminology that are valuable not only in building circuits but also in the use of commercially made amplifiers EQUIPMENT Prototyping board Oscilloscope Function generator Agilent 33220A Digital multimeter Agilent 34410A NPN Silicon Transistor 1 2N3904 Resistors 220 1 k 6 8 k 12k 82 k for CE amp Decade Box Capacitors 10 uF electrolytic for CE amp Copyright 2010 John A Goree Edited by John Goree 11 Jan 2010 PRELAB Identify all the formulas you will need in this Lab Compute the intrinsic emitter resistance re for a transistor with a collector current of I 2 mA Your answer should have units of Ohms Referring to your text or lecture notes describe the undesirable circuit behavior that can result if the dc bias of the common emitter amplifier s output is not centered between the two power supply voltages 73 PROCEDURE 1 Common Emitter Amplifier The common emitter amplifier shown below is based on Figure 2 37 in the text with changes to accommodate Vec 12 V instead of 15 V in the power supply The purpose of resistor R3 is to reduce the gain to avoid excessive high frequency noise 12V Vec common emitter amplifier Use the following resistor values R1 82k RC 68k R2 12k R 1k R3 220Q a Calculations Z Measure your component values If your multimeter h
89. ncy 100 mV to 3 Hz 5 Hz 0 070 0 000 or Period 750 V 5 Hz 10 Hz 0 040 0 000 10 Hz 40 Hz 0 020 0 000 40 Hz 300 kHz 0 005 0 000 Capacitance 1 0000 nF 500 nA 0 50 0 50 10 000 nF 1 pA 0 40 0 10 100 00 nF 10 pA 0 40 0 10 1 0000 uF 10 pA 0 40 0 10 10 000 uF 100 pA 0 40 0 10 viii Analog oscilloscope The display has about 8 boxes divisions in the vertical direction and 10 boxes horizontally It also has 5 small tick marks within each division You can usually measure a value to about 0 25 of a tick mark i e 0 05 divisions Example You use the oscilloscope on the 2 Volt div scale and your result is 5 3 Volt The error bar is 0 05 divisions so your final result is 5 3 0 1 Volt Propagation of Errors When two or more experimental measurements are combined into one by some mathematical operation such as a product P I V the two errors add in a non trivial way Example You measure I 1 2 0 1 mA and V 2 5 0 3 V The error on P is computed using partial derivatives as dP P D2 dI a P av 2 av 2 v2 d2 ay2 2 2 52 0 12 1 22 0 32 1 2 0 44 mW so the result you report for the measurement is P 3 00 0 44 mW II In general For F F A B C the uncertainty oF in terms of the uncertainties dA dB etc is given by dF2 gt F d A dA2 F B dB2 Note that errors add through their squares In this lab course you are asked to
90. nput terminals list of instruments used e g Tektronix 2235 oscilloscope Procedure A maximum of three sentences to explain what was measured e g amplifier gain what was varied e g oscillator frequency how etrors were estimated Results indicates a response is required where it is appropriate response should include table and or graph of results label each curve draw smooth curves through data points label axes and indicate units e g Hz mV estimate of errors for analog measurements as a column in a table or as a representative error bar on a graph sketch or print of the oscilloscope display if one was used and discuss briefly in a few sentences the features of the waveform to demonstrate that you understand the significance of the waveform timing diagram or truth table for digital circuits explanation of any problems you encountered Handwritten lab reports are adequate Typewritten reports are unnecessary Be brief but write in complete sentences For graphs you may use Graphical Analysis or other software If preparing your report consumes significantly more than two hours talk to your TA to ask if you are doing something that is unnecessarily time consuming Example lab reports are provided in the lab room for you to inspect Some instructors may not want error analysis included in the report Ask to be sure SYMBOLS USED IN THIS MANUAL a6 For your information Cm Instructions for you to follo
91. or Zener diode and its use as a voltage regulator Diode clamp circuit Silicon controlled rectifier SCR Note the instructor probably will choose not to do all of the above Professor Goree usually skips the SCR We will also build our measurement skills learning to use a digital oscilloscope 39 EQUIPMENT Digital Oscilloscope Function generator Multimeter handheld model only to protect the more expensive Agilent 34410A do not use it for this lab Prototyping board Transformer center tapped Power diodes 4 amp spares Signal diodes 2 Zener diode 1 amp spares Resistors Capacitors Variac Decade Box Potentiometer SCR 0 30 V de power supply 6 V lamp 3 terminal regulator 1N914 signal diode 8 V 1N914 or similar 5 Vorl0V 91 2 W 1k 2k 10k 56k 110k for SCR circuit 0 5 uF 10 uF 100 pF 2 1000 uF for SCR circuit 0 01 uF 4 7 uF for 3 term regulator for 3 term regulator 50k for SCR circuit for SCR circuit for SCR circuit 78L05 in TO 92 package for 3 term regulator Y cathode Power diode TO 92 package PRELAB 1 Identify all the formulas you will need in this Lab 2 Identify a type of connector you should not connect to a power diode to avoid melting it 41 PROCEDURE 0 0 Ohmmeter Check of Diode You will need a multimeter to confirm the polarity of a diode You don t need to report your results here in your lab report
92. orks as a pulse generator 3 Digital to Analog Conversion DACO808LCN or equivalent The DAC0808 is an easy to use 8 bit D to A converter DAC Wire up the DAC as shown in the figure Use wires to connect the inputs of the three most significant bits MSBs on pins 5 6 and 7 to the input switches on your prototyping board Connect the other four inputs to LO by connecting pins 8 through 12 with wires directly to ground Connect a multimeter to the analog output pin 4 Make a table showing all eight possible combinations of the digital input states on the three most significant bits Then measure the analog output Vout for all of these states 140 Vee 45V DAC0808 analog out VER 77 12V Analog to Digital Converter Note This circuit requires 23 wires to hook it up on your prototyping board An ADC is often used to interface digital circuits or computers to the real world especially to acquire data Your digital multimeter for example has an ADC Among other things an ADC contains comparators and voltage reference levels The incoming analog signal is compared to the voltage reference levels to determine which is closest A corresponding digital output bit is then set to TRUE An ADC is rated by the number of bits and the maximum clock speed 66 Here we will use the ADC 0804 an inexpensive ADC that is contained on one chip It digitizes eight bits at a clock speed up to 1 4 MHz
93. orrow these from lab coordinator if necessary Prototyping board Two short solid core wires to stick into prototyping board Alligator clips for multimeter test leads Boards with three terminals 2 Wire kit 2 A fuses may be needed by TA TA note Check batteries and fuses in all multimeters before use Check prototyping boards to verify that their power supplies work banana plug Multimeter PRELAB Identify all the formulas you will need in this Lab Describe one mistake that can damage a multimeter for each of the following measurements A voltage B resistance C current State whether propagation of errors can be used to find the uncertainty of A a quantity measured directly using a multimeter B acalculated quantity based on more than one measurement C both of the above Use the resistor color code chart to determine the value of a four band resistor with the colors brown black brown gold Multiplier wire e i 4 EXAMPLE at i 47 000 Ohms Day or Multiplier A7 KA Tolerance 2 Red 5 Gold 10 Silver PROCEDURE Familiarization with equipment The digital multimeter The hand held digital multimeter is used widely to make electrical measurements of voltage dc amp ac current dc amp ac resistance continuity other quantities such as frequency depending on your meter s features Input impedance In the voltage mode the input imped
94. otect the decade box always keep 100 Q switched in while you adjust the other scales This precaution will keep you from accidentally setting the decade box to zero resistance ii Regulation Vary R beginning at 10 1 kQ and stepping downward to 500 Q amp Note the load resistance above which the voltage stays approximately constant To what current does this correspond SCR Circuits optional depending on whether TA finds there is enough time a DC Control RC Timer The circuit in Figure 3 8 switches on a voltage across the load after a delay The SCR switches on when the gate voltage G exceeds the cathode voltage C The gate voltage is developed across the capacitor C4 by the R C combination Short C to remove all charge i Switching time Turn on the supply and determine the time for the voltage to be switched across the load ii Gate voltage Short Cj again and repeat with each of the resistors in the time constant portion of the circuit Determine the gate voltage necessary for firing 55 scope in CH1 scope in CH2 6V scope GND Figure 3 8 RC Timer b AC Control Lamp Dimmer In the circuit in Figure 3 9 the R C combination acts as a phase shifter for the 60 Hz AC voltage As R is increased the phase is shifted from 0 to 90 With this circuit it is possible to control the output half wave from completely on to completely off Use the input from
95. otyping board use wires to connect the outputs of the 12 V power supply and ground three wires in all as shown in the left of Figure 4 5 to a couple of strips that look like those shown on the right of Figure 4 5 Set up the Agilent 33220A function generator to produce a sine wave that is symmetric about zero volts turn off the offset Initially adjust it for f kHz and P P amplitude 2 V Do not use the Burst or Sweep modes here If output button is not lit there will be no waveform applied to the instrument s Output Set up the oscilloscope to show a dual trace using DC input coupling with one channel Agilent 33220A Function Generator showing in and the other showing out Be sure the grounds of the oscilloscope function generator and prototyping board are connected i input and output waveforms Print the oscilloscope display and number your printout so that you can identify it in your report Repeat for an input amplitude that is much larger and much smaller Comment on any significant differences ii operation with non symmetric power supply amp Now connect the emitter return the resistor on the bottom of the figure to ground instead of 12 V Observe the display for several amplitudes of input Explain how the circuit functions more poorly 63 iii breakdown Look for bumps appearing at reverse bias This is called breakdown Measure the breakdown vol
96. ping of the waveform Sketch or print the waveforms and mark values at particularly significant times 4 Difference Amp 66 The circuit in Figure 7 6 is a differential amplifier Recall that the common mode rejection ratio is defined as 92 CMRR differential mode gain common mode gain i e CMRR Ap Ac ee Using Op amp rules 1 and 2 as described in the text one can derive that the output is R2 R4 R R2 ves an Vin2 RaR 4 1 Note that if R1 R2 R3 R4 then the output is a simple difference Vout Vin2 Vin1 4 2 More generally we can find expressions that are valid even if the resistor values are not all exactly identical which of course they won t be in practice due to resistor tolerances Substituting Vjn7 Vin2 we find that the differential mode gain is Ap Ro R 4 3 Substituting Vin Vin2 we find that the common mode gain is R2 R4 Ri Ro R Ry R3 R4 4 4 which is zero if R3 R and R4 R2 So the CMRR Ap Acis perfect infinity if R3 R and R4 R2 However resistors actually have a tolerance of typically 5 and therefore the common mode gain will not actually be zero and the CMRR will not be infinity 93 R2 R1 int O R3 R4 Figure 7 6 Differential Amplifier Connect the circuit in Figure 7 6 using resistor values R1 R2 R3 R4 10 k a Differencing A Use the setup with a sine wave and a dc signal set up that yo
97. quency is determined by R and C as it was in the 555 timer A to D Conversion Connect a DMM to measure dc voltage across the differential input to the ADC i e between pin 6 and ground If it looks like too many LEDs are lighting up the input voltage may be jittering near the borderline between digital levels causing a fast alternation between one digital level and another and because of the fast clock speed it looks like all the LEDs are lit Try adjusting the input voltage slightly up or down Vary the input voltage from 0 V to 5 V and record Vin at the 8 levels where the three most significant bits of digital output change from LO to HI Present your results in the form of a table Using the function generator produce a triangle wave or sine wave varying from 0 V to 5 V at approximately 0 1 Hz and apply this signal to the input Watch the LEDs as they change and be sure that you understand why they change as they do 143 R 10k WW C 0 001 uF 1 TS Voc 20 Veet 5V 2 RD CLKR 19 LSB Ry 3 WR DBO 18 4 CLK IN 17 analog er input 5 INTR 16 6 Vin 15 digital output 7 Vin 14 ae 8 A GND 13 9 V REF 12 on MSB 10D GND V a ADC 0804LCN note grounds a C2 0 01 uF A analog gnq IIl IIl Test circuit for the ADC 0804 analog to digital converter Use the GND on your prototyping board as both the analog and digital grounds The manufacturer designed the chip so that it can be used with two separat
98. r science At the end of this course the student should be able to 1 design and build simple circuits of his or her own design 2 use electronic test amp measurement instruments such as oscilloscopes timers function generators etc in experimental research REFERENCE This manual is intended for use with the following textbook Horowitz and Hill The Art of Electronics 2nd Edition 1989 1990 Cambridge University Press DATA BOOKS Data books such as the Texas Instruments or National Instruments references for TTL CMOS and LINEAR circuits should be used by the student to check pin designations outputs and other data not given in this lab manual These books are on a shelf in the lab iii LAB NOTEBOOKS As a part of training to be a scientist students should maintain a personal notebook just as a research scientist does This lab notebook will not be graded but the student must have one and use it A lab notebook with a sewn together binding is preferred Here is a guideline for lab notebooks a notebook should contain sufficient detail so that a year later the experiment could be duplicated exactly In the notebook the student should draw a schematic diagram for every circuit that is built a label this diagram with e part numbers e pin designations e output input designations a show the major connections to external power supplies etc list the instruments used by type and model a include in this li
99. r of the state HI or LO ALWAYS USE A RESISTOR IN SERIES WITH THE LED The series resistor 220 Q typical is needed to avoid destroying the LED The LED is a diode and when it is on it has very little resistance If you connected an LED directly between a source and either ground or Ve it would try to pass an infinite amount of current which will burn up the LED 220 Q About buffers for the LED A buffer is often needed to drive an LED The outputs of many gates and circuits cannot source enough current to drive an LED directly this is when you must provide a buffer The buffer is a digital version of a follower its output is at the same voltage as the input but is capable of driving more current while sinking very little at its input Your prototyping board has LEDs that are LOGIC INDICATORS already wired so that you can use them as digital indicators La La L2 cS 105 without a buffer one part next part of digital of digital circuit circuit with a buffer one part next part of digital of digital circuit circuit 106 1 This step is omitted from this manual 2 The 04 Hex inverter Use the 5V power supply for Vec Install the 04 hex inverter on the prototyping board Examining the pin diagram choose any of the six inverters Connect its input to a data switch and its output to a Logic Indicator LED
100. servations are consistent with the description high pass filter C2 50 pF R1 C1 R2 1k 0 01 uF 100 k out Figure 7 8 Op Amp Differentiator 96 Comparator You will observe how a comparator will output a relatively clean digital output 5V or OV depending on whether an analog input voltage is gt or lt a threshold voltage You will establish the threshold voltage using a potentiometer You will also observe an undesired oscillation in the comparator s output a d you will diminish this oscillation by adding positive feedback to the comparator Connect the comparator chip as shown below Use the power supplies of the prototyping boarding 12 V power supply for analog 5 V power supply for digital lV Fine Gon ESI orsel k K 3 aps sok KAT volhy were sul AG ley a ibd Adjust the function generator to provide an 8 V peak peak sine wave at 1 5 kHz Observe the digital output of the comparator on CH1 of your oscilloscope and the sine wave analog input on CH2 Trigger the scope on CH1 using the falling edge with 100 microsec division for the horizontal scale 97 Record the oscilloscope display when the threshold is set to the following two values i 3 V ii 0 V Discuss qualitatively how the output waveform changes states in response to e Upgoing analog input voltage e Downgoing analog input voltage Now zoom in to the downgoin
101. source waveform trigger level time trigger event trigger event with positive with negative slope slope Figure 2 1 b Oscilloscope triggering 17 t 041048 171435 Q NOILISOJd 43S AMS 8 Y NOILISOd adOODSOTWNOSO ZHW OO g One use of the oscilloscope is to measure relative phases between two waveforms This is done by adjusting both waveforms so that they are symmetric about the horizontal line in the middle of the screen Then note the time delay At between the zero crossings as shown in Figure 2 2 This corresponds to the phase shift which is 360 At T Figure 2 2 Tip Sometimes it is hard to get anything to show on the scope In that case follow this procedure e set trigger to AUTO DC COUPLING CH1 e set horizontal mode to A e set vertical mode to BOTH set sweep speed to 1 ms div CAL MAGNIFIER OFF e set vertical coupling to ground e turn up intensity e wiggle vertical position until a horizontal line appears e set vertical coupling to AC or DC 19 lt Signal output SYNC output 4 labeled TTL CMOS BK4017 Function Generator 20 Signal output YSINYSA to z o o i S o o z O i I o t oz Os a YJINYIJA vo co e o i o z o l D o p O z 1 08 4 0 01 S O A JONLNdWYv i labeled TRIGGER SYNC output 1NdLNO ysaOOINL YSINYSA YSINYSA YJ
102. st oscilloscope multimeters function generators etc draw the appearance of the oscilloscope display if used Q indicate the vertical and horizontal scales with units record a table of all measurements include units e g mV for inputs and outputs record the scale e g 200 mV of the meter or oscilloscope indicate where on the schematic the measurement is made for digital circuits this table may be in the form of a truth table DODO for measurements that have an uncertainty a list more than one measurement as an error check Q estimate the error bar PRELAB In each lab you are given prelab questions These are intended to help you prepare for the lab You should write your response in this manual These questions are not handed in and they are not graded If you do not understand a prelab question be sure to ask your TA iv LAB REPORTS For each Lab students will individually prepare a lab report for grading This report is distinct from the notebook the notebook is not a substitute Reports should be organized as a brief introduction and then an experimental section that is organized according to the section number indicates where your response is required Preface brief introductory paragraph 30 words describing the report s theme Experiments REPEAT THE FOLLOWING FOR EACH SECTION Apparatus schematic diagram labeled with part numbers e g 1N914 diode pin designations on IC s output i
103. stead you would choose a laser diode which is much faster and costs 10 Replace the HLMP C1115 with any common LED for example a red diffused LED like the one used in Experiment 8 and repeat the measurements of the time response for that LED For both measurements HLMP C115 and the other LED identify the component or instrument you believe is most responsible for the finite rise time that you measured and discuss briefly how you came to that conclusion o When finished reset the CH1 and CH2 menus so that it has Probe 1X not Probe 10X so that this does not confuse measurements made with this scope in following labs Note 2008 manufacturer s specification at Voc 10 V Ice 1 mA R 100 Your result might be slower at parameters different from these 84 8013B PULSE GENERATOR HEWLETT PACKARD 10 0 RATE Hz PULSE PERIOD s VERNIER ae s 5 5 HEXT 20n 1p gt Am 10m 1 ae _ _ i 50M5 IM gt 10k gt 100 1 5 41 0 0 4 PULSE DELAY s VERNIER VERNIER PULSE DOUBLE NORM 35n 1p gt im gt 10m 1 AMPLITUDE V PULSE WIDTH s VERNIER p OFFSET 2 5v TAVARE ETR WAVE l 10n Ip z Im 10m 1 TRIGGER GATE TRIGGER INPUT INPUT OUTPUT dicated in instructions Tek P g Trig d Mi Pos 15 00 us Ee e a Oe OEE Oe eee Oe RO CO eee ee 2 ere ee ee 2 Se eee ee ee eh Bee 6 8 ee 6 eo eee ee ee 8 8 Oe 2 OO Oe et ee 8 PAG Fb Ee Se oS e 818 S le Se a ee De M
104. sured on the multimeter within the error bars for the two measurements As a rule remember that meters on a power supply are usually less reliable than multimeters Always make measurements of voltage and current with an external meter amp As always in both your notebook and report draw the schematic for whatever you connect including external instruments For this measurement it looks like the example below Schematic Power supply 2 AC voltage and frequency ee No error measurements are required for this section Set the AC DC switch of the multimeter to AC and reset the scale to maximum voltage Plug the primary of the transformer it s labeled 8 V rms but you will measure this yourself into the AC outlet and measure the AC voltage of the transformer secondary The wiring in a building in the USA is nominally rated at 110 V rms but will vary from this value Since this is connected to the primary of the transformer and the voltage on the secondary is a fixed fraction of the primary voltage you may find that your output voltage is not exactly the level printed on the transformer The electrical generators used by utility companies produce a 60 Hz voltage If your multimeter has a frequency Hz feature use it to measure the frequency of the transformer output Return the multimeter s ac dc switch if there is one to dc Transformer 3 Resistance Set the function switch
105. tage i e the voltage at which breakdown first occurs Compare your result to the specification in a data sheet for the transistor Note the breakdown voltage specifications for the 2N3904 and the 2N4400 are identical so for this purpose you may use either data sheet iv voltage gain Connect the emitter return back to 12 V Add a blocking capacitor to the output as shown in Figure 4 6 Why don t we use a blocking capacitor on the input It s not necessary When the function generator feeds the base directly the DC bias of the base is held to that of the function generator which is near the middle of the transistor s operating region That s where we want it 12V Voc in 10k 2N3904 0 1 uF T R ES 3 3k 12 Figure 4 6 amp Adjust the input amplitude of the sine wave from the function generator so that the output looks like a good sine wave Measure the ac voltage gain v blocking capacitor test 64 amp Use your oscilloscope with dc coupling to measure the dc bias of the output on each side of the output capacitor Confirm that the output capacitor is blocking a dc bias Note the following procedures for measuring input and output impedances will be used again in later experiments 65 b Input Impedance You will measure the input impedance Zin Because there is no significant capacitance or inductance at the input of this circuit we can write that Zin Rin See the discussion and di
106. th so that you can accurately find its maximum typically this will require that you see about two complete oscillations in the horizontal direction O Use the second trace other input channel with a GND input to make a cursor as an optional aide in measuring the waveform s height Measuring time O Adjust the vertical scale to overfill it by a significant amount so that the waveform looks like almost straight vertical lines then look for zero crossings O Use the lowest practical intensity O Adjust the horizontal position so that one of the zero crossings occurs on a major division of the horizontal scale O Choose an appropriate time scale for best resolution in measuring the time typically about 1 5 or 2 complete oscillations displayed Demonstrate the use of the dual time base 22 PRELAB 1 Identify all the formulas you will need in this Lab 23 PROCEDURE Read Appendix A in the text You will need to know oscilloscope terminology before you begin In this lab you will record a lot of data It is recommended that you record it in columns in your lab notebook with separate columns for the reading e g in mV the scale on the oscilloscope e g 100 mV per division the estimated error for each measurement 1 Measurement of Voltages a DC Voltages To start adjust the oscilloscope settings to the following vertical mode CH1 CH1 Volts Div 1 Volt use 1x indicator on dial input coupling
107. the transformer secondary as a reference signal for the oscilloscope Observe the phase shifted wave across C and the output wave across Rz Explain why the lamp dims 5V Lamps 1 or 2 110 VAC a3 i Figure 3 9 56 Lab 4 Junction Transistor Part I REFERENCE Horowitz and Hill Section 2 01 2 12 Appendix G Appendix K data sheet for 2N4400 INTRODUCTION Junction transistors are either NPN or PNP with the symbols in Figure 4 1 Small signal type transistors come in various pin configurations An NPN in a TO 92 package is shown in Figure 4 2 In the junction transistor a small base current few A controls a much larger Emitter Collector current 1 0 mA You will demonstrate the transistor in three common applications e Emitter Follower Common Collector Amplifier e Transistor Switch e Current Source Better performing than the one in Lab 1 This experiment will also improve your skills at wiring circuits and using test amp measurement instruments EQUIPMENT Prototyping board Digital Oscilloscope Function Generator Agilent 33220A Pulse Generator HP 8013B Digital Multimeter Agilent 34410A NPN Silicon Transistor 2N4400 for switching you may substitute 2N2222 2N3904 for amplification Light bulb typically 47 0 15 A 6 3 V with wires Resistors 1 KO 3 3 KQ 10kQ 22 KQO 33 KQ 1 MO Decade Box Capacitors 0 1 uF Copyright 2010 John A Goree Edited by John Goree 11 Jan
108. tion generator output to such a low amplitude Make sure that the grounds of the function generator oscilloscope and prototyping board are somehow connected Measure the values of your resistors then using the prototyping board wire up the inverting amplifier shown in Figure 7 3 R2 1k 10 k 22k R1 1k in O out Figure 7 3 Inverting amplifier a Gain 1 Measure the gain Ay for Rp 1 k 10 k and 22 k ii Using measured values of R2 and Rj compare to Ay R2 R1 iii Verify that the amplifier inverts b Saturation For the circuit with Ro 22 k increase the input signal amplitude to observe clipping Calculate the ratio Vout Vin that corresponds to a 3 dB drop in gain Measure the input amplitude that results in clipping with a 3 dB reduction of the output as compared to the ideal output amplitude What is the output amplitude as a ratio of Vec when clipping occurs at this level 90 c Frequency response i roll off frequency For the circuit with R 22 k vary the frequency from a low value 100 Hz upward to find fz gp the frequency at which the gain drops by 3 dB Compare to the value given by Figure 4 31 in the text ii graph of frequency response For the circuit with R 100 k measure the gain Ay at the logarithmically spaced frequencies of 100 Hz 300 Hz 1 KHz 3 kHz 1 MHz 3 MHz Repeat for Ro 10k Plot your results on a log log graph A
109. u used for the summing amp Verify that the output is the difference of the two inputs as predicted by Eq 4 2 by marking values at particularly significant times on the printout of the scope display b Differential mode gain Z Apply the sine wave to input 1 and connect input 2 to ground Measure AD Vout Vin Compare to the value predicted by Eq 4 3 using actual measured values for the resistors c Common mode gain Connect both inputs to the sine wave Measure AC Vout Vin Compare to the value predicted by Eq 4 4 using actual measured values for the resistors d CMRR Compute CMRR AD AC 94 5 Integrator low pass filter The circuit in Figure 7 7 is an integrator which is also a low pass filter with a time constant Rj C Resistor R provides DC feedback for stable biasing since without it there would be feedback through the capacitor only and that would not provide any DC feedback Note if you observe a severe dc offset on the output of the circuit you may replace R2 with a 100k resistor 1 The output is Vout RC fva dt const 1 Adjust your function generator to produce a square wave which will be applied to the integrator circuit s input a Integration Print waveforms for Vin and Vout at 1 kHz b DC stability ZA Remove the resistor R2 and see if anything unfortunate happens to the output waveform the effect might not occur or it might not be extreme B
110. ure to add an arbitrary DC offset to the output A pulse generator is usually not bipolar and there is usually no DC offset adjustment A pulse swings between zero and either a positive voltage as in the case of logic circuits or a negative voltage Pulse generators are used to clock digital circuits 5 V OVS T ool quare wave 5 V T a ite el pulse train clock 134 d ras meiretiijee a te ea Ptkoes eos dai eT a a oe shpre oeras coe e res A 1 AAS VAREN BOn S we Lab 10 circuit as wired on the prototyping board at the end of the Lab 135 PRELAB Identify all formulas used in this lab While an analog voltage can have an unlimited number of values a digital signal has a limited number of discrete values How many discrete values can be represented by 8 bits of data What is the sensitivity mV per degree C of the temperature sensor you will use 136 PROCEDURE 1 555 Timer used as an oscillator a b c 66 Timer circuits are common in many of the instruments that are home built in research laboratories A favorite and easy to use chip is the 555 timer or a modernized version such as the 7555 With this chip you can easily build a simple oscillator or other waveform generator 66 Here you will build a square wave oscillator Using the prototyping board build the circuit shown in the figure Use 5 V from your prototyping
111. use propagation of errors only twice both times in Lab 1 in order to develop this skill These two instances are indicated in Lab 1 with a footnote Otherwise to save time do not perform propagation of errors analysis TO THE INSTRUCTOR HOW ONE CAN USE THIS MANUAL This manual is intended for a one semester course The instructor probably will skip some experiments or parts of experiments due to lack of time The first few experiments analog circuits will challenge the student the most One option is to skip some of the Labs and then finish with a special project This special project is a circuit invented by the student it requires about four weeks The student must begin planning a special project several weeks before this four week period begins TO THE TA Before the students do their experiments you must e do the experiment yourself e inventory parts to be sure they are all available e setup each lab table e check batteries in multimeters for example If enough parts are available leave your setup in working order for students to examine when they have difficulty You will need to schedule additional time in the lab to accommodate students who are unable to complete their work in 3 hours Students need their graded lab reports within a week of handing them to you If you take longer to grade them students will not know whether they were writing their report as expected or whether they are omitting required infor
112. utput Then reduce R until the peak to peak output signal falls by 2 Then Rz equals the output impedance of the circuit d Comparison Compare the measured input and output impedances by calculating their ratio Rout Rin Usually it is desirable for an amplifier to have a high input impedance and a low output impedance To what extent is that true here Transistor switch Transistors are used often as switches One application is cold switching where a remotely located mechanical switch which carries little current controls a larger current someplace else A transistor switch operates in the saturated mode when the switch is on and in the cutoff mode when the switch is off It should not be operated in the normal or linear mode where I hfe Ip See Appendix G in the text for more on saturation Use a wire on your prototyping board instead of a mechanical switch Using the 5 Volt power supply that is built into your prototyping board wire up an NPN transistor as a cold switch as shown in Figure 4 9 The lamp is the load here The 10 k resistor is not essential it makes sure that the base is near ground potential when the switch is open 67 a Cold switching V VG 1k gt mika a S Figure 4 9 Cold switching Z Verify that the lamp is turned on as you close the mechanical switch and off as you open it b Current through the switch Setting your
113. w Z Requires an answer or comment in your lab report RESISTOR COLOR CODE MULTIPLIERS TOLERANCES Silver 2 Gold 1 Black Brown Red Orange Yellow abcd 0 1 2 3 4 Green 5 Blue 6 Violet 7 8 9 none 20 silver 10 gold 5 Gray White 6 abx10 Q d t as of 2001 Graphical Analysis was installed on PCs at this location Start Programs Vernier Software GA vi TREATMENT OF EXPERIMENTAL ERRORS Error does not mean a mistake It means an uncertainty In measuring any value the result is not just one number such as 5 3 Volts It is two numbers 5 3 0 1 Volts The second number is the experimental uncertainty or error bar It usually represents one standard deviation one sigma from the first value In making an analog measurement with a meter or an oscilloscope you should record not just the first number but the error as well To decide what value to assign to the error you must use some judgment Here are some tips Multimeters The manufacturer gives specifications for the precision for the multimeter The precision of a BK model 388 HD hand held multimeter is DCV ACV F 50 rd 25 rd 00 rd 50 rd 00 rd LS LS LS LS LS LS LS ACA DCA Q HZ 75 rd FOrRPRPNR oO WwW e PrP WwW Pe BP BR Q Q Q Q Q Q Q G G e UV UU DY 00 rd where rdg is the reading on the display and LSD is the least significant digit Example You
114. x L The One Shot you will use has a Schmitt trigger input for the B input Schmitt trigger inputs fire when the input exceeds a certain threshold and reset when the input voltage drops below a lower threshold Schmitt triggers are widely used to produce a jitter free pulse from a noisy input signal Refering to the specification sheet connect the 121 on the prototyping board as follows Connect an 0 1 uF capacitor between pins 10 and 11 The one shot you will use has an internal timing resistor with a nominal value of Rint 2 KO refer to the data sheet to confirm this value 1 Q output 8 NC 2 NC 9 Timing pin Short to pin 14 3 input Al GND 10 Timing pin C 4 input A2 GND 11 Timing pin C 5 input B 12 NC 6 Q output 13 NC 7 GND 14 5V a amp Set up the pulse generator to apply a 10 V peak square wave to the input of the one shot Use a frequency f 1 kHz amp By varying the input amplitude measure the trigger voltage Measure the pulse width Compare to Rint C In 2 b 4 Reduce the pulse width and verify that the pulse width at the output of the one shot is unaffected by the pulsewidth at its input 139 c 4 Replace the shorting wire between pins 9 and 14 with a 10 k resistor and measure the pulse width d A At the input replace the signal from pulse generator with the square wave signal from the 555 timer that you built in part 1 Verify that this combination w

EXPERIMENT M3: - John A. Goree

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