Universal Transconductance Amplifier User Manual
Contents
1. 2a Check the position of the jumpers on JP1 and on JP2 against the diagram attached to the inside of the lid of the enclosure and the calibration label Is the setting correct 2b Be sure you are using the correct multiplier in your calculations Refer to the table on the previous page and the jumper positions in the box The version number should be printed on the top label or on the calibration label 2c Place sensor in full unobstructed sunlight you should see a significant increase in output voltage Indoor light ing is much much weaker than full sunlight The standard amplification factors are designed to accommodate full tropical sunlight conditions If you will be using your sensor in generally low light conditions say indoors or in the arctic or under a plant canopy you may wish to select a higher output voltage setting to bring the signal into the dynamic range of your data logger Please consult the LI COR literature and references or contact EME Systems for assistance 2d The power supply must be at least 2 volts greater than the desired full scale output voltage except the UTA HOBO version which operates rail to rail 3 The amplifier output is unstable and readings fluctuate too much under constant lighting conditions Things to check 3a Check all of the connections to the screw terminals Make sure all connections are tight and secure 3b Check for an AC component in the power supply voltage The power supply should be filte2. uamps previously 12 5 amps to allow for higher LI190 outputs full scale for pyranometer was changed to 120 pA and photometer was changed to 48 A full scale Rev C is indicated on the top label of the UTA enclosure 3 HOBO is a trademark of ONSET Computer Corporation Bourne MA U S A www onsetcomp com rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com 8
3. will be a special jumper on the LI 190 setting of jumper block 1 See figure 2 below The special jumper is on this LI 190 setting rather than the LI 210 setting in order to maximize the Ist stage gain from the photometer Jumper Block JP1 3 position LI 190 Use only one jumper to LI 200 select proper LI COR sensor L 210 Power supply input and signal output Li Shield or sea Bare Wire Input Clear wire d Normal Jumper UTA jumper and connections diagram Notes e Choose a full scale output voltage less than or equal to your logger s input capability but not too much less For example if your logger has a full scale input range of 2 5 volts you should choose the 2 volt position e If you select too low a setting you will lose resolution and your logger will not register subtle changes and may fail to register the lowest light levels of interest 10 0 V F S Jumper Block JP2 4 position Use only one jumper to select desired full scale output Special Jumper rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com 2 e If you select too high a setting the amplifier may overdrive or saturate the input circuit on your meter or even damage its inputs Th
4. 00nA 1000 W m2 1 2 5 10 Volts out 125A input LI 210 Photometer 40nA 100 klux 9290 ftcd 1 2 5 10 Volts out 50uA input Alternate gain settings are available on special order In particular a special UTA HOBO is available for use with ONSET HOBO data loggers Also higher gains are available for use of the sensors at low light levels indoors or underwater The calibration tag provided by LI COR with each sensor in conjunction with the preset amplifier gain factor can be used to compute the light levels incident on the sensor with a high degree of accuracy Specifications e Supply Voltage 5 24 VDC supply volts gt full scale output volts 2 e Supply Current less than 1mA e Gain accuracy 0 5 all ranges 0 2 on factory preset range Voltage output in darkness lt 4 millivolts e Supply Voltage variation effect less than 0 01 per Volt e Response 2 milliseconds e Operating Temperature 30 C to 70 C e Tempco less than 0 01 per C e Output impedance 1000Q 1 e NEMA 4 gasketed white polycarbonate enclosure 1 37 x 1 96 x 2 55 4 15 w glands gland nut or BNC at input gland nut at output Phoenix beryllium copper i o terminals Order item description price ea GE ME ET base price standard UTA with i o cord grips polycarbonate enclosure 105 Options se EE BNC connector on input add 10 input preset cesses preset input for LI 190 LI 200 or LI 210 no charge output p
5. Mounting Template not to scale rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com 7 UTA Schematic The information contained herein is provided as an aid to resolving questions about the amplifier and its application It is not meant for general distribution and remains the exclusive property of EME Systems Gain Sensor J5 1X R4 66 5K 0 1 Li 190 J2 R12 11 3K 0 1 J6 2X R3 8 87K 0 1 Li 200 J3 R11 45 3K 0 1 J7 5X R2 22 1K 0 1 Li 210 J4 R10 102K 0 1 J8 10X C1 0 001 uF C2 0 001 uF D2 SD103 R1 100 LT1078IN 5 bata White QO 1 064 V 5 to 18 inner RED 6 8 t 10V 7 R7 1K O Signal aa Gain RT1 GREEN D1 Trim 2K 4 Li 200 47 Li 210 sy R13 1N5230 not used 2 3 0 1pF R9 pulldown C4 0 1 11 3K BLACK 0 1 Shield ommon O OBLACK UTA Universal Transconductance Amplifier Rev C UTA 10 2002 EME Systems 2229 Fifth St e Rev B changed LI190 fs to 16nA Berkeley CA 94710 e Rev C changes first stage gain for 16uA 1204A amp 48nA fs e Rev D changes first stage gain for 16 67A 125A and 50nA fs tel 510 848 5725 e can use LTC1047 for highest accuracy fax 510 848 5748 e Special for HOBO short D1 UI LT1490A gain 2 5 16 9 KO at jumper 5 info emesystems com 1 LI 190 LI 200 LI 210 and part designations are trademarks and the exclusive property of LI COR Lincoln Nebraska 2 In revision C the full scale for PAR was changed to 16
6. Universal Transconductance Amplifier Universal Voltage Output Amplifier for LI COR Sensors Amplifies LI COR sensor current to voltage logger level Revision D User Manual Contents TAtrOGUCHON es ED EE DE ota 2 Configuring your UTA esse esse es ses se ee ee ee RA Ge Re ee 3 CONTEC TIONS as sl n Ee Ee ee De ie ee le 4 CAlCUIATIONS scsi einai ee EG aes 5 PROUD IE SHOOTING Re EN N Ge EL GN Ge EI ee 6 TTA Reealibraulon s GOEDER Re T A RENAR 6 Physical Dimensions ie ee ee ee ade 8 UTA Circuit Schematic N ee de N Ge Ee GN N ee 9 rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com Universal Voltage Output Amplifier for LI COR Sensors Amplifies LI COR sensor current to voltage logger level Revision D The UTA is a special purpose amplifier that converts the microamp level current output of LI COR light sensors to a corresponding signal voltage The UTA can be configured at EME Systems or by the end user for any one of the three standard LI COR sensors and for any one of four popular output voltage ranges through the manipulation of two plug in jumpers The UTA provides a simple interface between LI COR sensors and voltage input data loggers chart recorders HVAC and greenhouse control systems LI COR sensor Typical full sun response UTA output user selectable LI 190 PAR sensor 12 15uA 2000 pE m s 1 2 5 10 Volts out 16 67uA input LI 200 Pyranometer 1
7. boring black terminal or LIXXX SA BNC termination LI COR part numbers ending with a SA are terminated with a BNC connector and should be used with the UTA BNC amplifier Simply align the connector with its mate on the outside of the UTA BNC and twist the two halves together The BNC connectors should lock together when they are properly seated b Connect the power supply from your data logger between the black common and red DC voltage terminals on the opposite end of the circuit board The power supply voltage must be at least 5 volts and must be greater than or equal to the full scale output voltage you select for the UTA ie if using the 10 0 V F S setting your power sup ply must provide at least 12 volts or it must provide 7 volts power for 5 volt output or 5 volts power for a 1 or 2 volt output The UTA draws less than 1mA of current making a battery a viable option for a power supply c The signal from the UTA should be taken between the green and black terminals Green is signal and black is common ground The green terminal should be connected to the signal input of your logger and the black terminal should be connected to the power supply ground Note that the black terminal is common to both the power supply and signal line 3 Check all connections for proper polarity and be sure all wires are clamped solidly in place Replace the top cover on the enclosure and tighten the corner screws Take care not to over tighte
8. e highest light levels will all register as one value off scale e You may wish to purposely select a higher output setting to achieve greater sensitivity at low light levels This might be useful in studies of indoor lighting where full sun intensities will never be attained e The UTA power supply must always be greater than or equal to the full scale output voltage e Use alcohol to rub off the old mark on the calibration label and a Sharpie marker for the new one Connections 1 UTA amplifiers are enclosed in a protective cabinet To gain access to the connection terminals and jumper blocks remove the two corner screws using a standard screwdriver and lift up on the top 2 Refer to figure 2 The UTA has connections for the LI COR sensor input at one end of the circuit board and for the power supply and signal output at the other end The input connections may be either a pair of black and white color coded screw terminals or a BNC connector The UTA power supply and output signal is always terminated with a strip of three screw terminals color coded red green and black a LIXXX SZ bare wire termination LI COR part numbers ending with SZ are terminated with a stripped and tinned bare coaxial cable These sensors should be used with a standard UTA amplifier Connect the inner conductor green white or clear to the white colored terminal on the UTA board and connect the outer wire shield or tinned copper wire to the neigh
9. emesys com 5 Precision 4 digit DVM UTA Circuit board l See Precision Floating HE Current Source Foo Isink Gnd o O D S amp mi g Regulated DC power supply NA eee o o N ay TT HAP TT Vou Gnd t o F First stage gain trimmer adjustment Notes e Each LICOR sensor has an individual calibration tag The standard calibration of the UTA requires that the calibra tion constant be entered in software Alternatively a UTA can be calibrated to match an individual LI COR sensor so that say 1000 watts meter2 input will give 4 00 volts output That UTA then stays with that particular LICOR sensor In effect the calibration is done in the hardware rather than in the software The advantage is that it simpli fies the software particularly where a low resolution converter will be used or where calibration constants can not be entered in software or where several light sensors must be interchangeable without reprogramming The disad vantage is that if the LICOR sensor needs to be replaced or recalibrated then so must its attached UTA For example suppose you have a Quantum PAR sensor LI 190 and that its calibration tag states a multiplier of 187 5 UE m2s per uA Suppose you want to calibrate the UTA to have an output of e
10. figured for the appropriate sensor and full scale output voltage you need The preset value is marked on a label outside the UTA enclosure If so please skip to connections on the next page This section explains how to configure the UTA for different sensors and output ranges 1 UTA amplifiers are enclosed in a protective enclosure To gain access to the connection terminals and jumper blocks remove the two corner screws using a standard screwdriver and lift up on the top 2 Refer to the diagram below for the position of jumper blocks JP1 and JP2 Each jumper block should have only one jumper in place Choose the jumper position on JP1 that corresponds to the type of LI COR sensor you will be using Choose the jumper position on JP2 that corresponds to your desired full scale output voltage To move the jumpers pull them up and off the posts and plug them back into the desired position A copy of this diagram is attached on a label on the inside the lid of the UTA enclosure 3 If you ordered a special calibration for your UTA then it may have a special jumper The special jumper has a resistor soldered to it see figure 2 below For example a For a UTA HOBO there is a special jumper on the 1 V F S setting of jumper block 2 see figure 2 below This jumper allows the UTA to reach the 2 5 Volt F S requirement of the HOBO b For a special LI 210 photometer calibration that allows the photometer to register very low light levels there
11. n the cover screws as this may cause the cover to deform or saddle which can compromise the seal Note Noise sources For long runs in the presence of halide lamps or other noise sources you should consider using shielded three wire cable for the power and signal connections between the logger and the UTA with the shield tied to common at one end only Long wire runs The LI COR sensors come with 10 feet or 50 feet of cable The rest of the wire run from the UTA to the data logger or controller should be made with 22 gage or heavier wire The current flowing in the ground lead creates an error voltage that is added to the apparent output signal For example 1000 feet of 22 gage wire has a resistance of approximately 15 ohms The UTA power supply current of 0 0005 amp flowing in that wire would create a 7 5 millivolt offset On the 5 volt scale the error would be 0 0075 5 100 0 15 It is unlikely that you will be using such long wire runs However poor connections in the ground lead can provoke similar errors Be sure the ground lead is well secured The UCLC amplifier is better suited to transmission of data as a current over long distances rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com 3 Calculations In order to convert the UTA s output voltage into the appropriate units of light you will have to program your equip ment to multiply the UTA output voltage
12. ppose your meter has a full scale input of 5 0 volts You choose the 5 0 volt output setting for your UTA with a transconductance gain of 25 uA V 3rd column 2nd row in table The conversion is light level in Wim UTA volts 9 8 25 UTA volts 245 W m2 per volt A 4 6 volt output signal would indicate 1127 W m Example 3 Suppose you will be using your UTA in conjunction with a Photometer sensor LI 210 and that the Photometer calibration tag states a multiplier of 2 63 klux uA Suppose your recorder has a full scale input of 2 5 volts You choose the 2 0 volt output setting for your UTA with a transconductance gain of 25 uA V 2nd column 3rd row in table The conversion is light level in klux UTA volts 2 63 25 UTA volts 65 75 klux per volt A 1 25 volt output signal would indicate 82 2 klux If you need units in footcandles 1 footcandle 10 764 lux Notes 1 If you need more sensitivity at low light levels choose a higher UTA transconductance gain or contact EME Systems for a special calibration 2 If you ordered a UTA HOBO please refer to the document Additional Documentation for the UTA HOBO for calculations and other information This document is also available online as a PDF at http www emesystems com uta_hobo_dat htm rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com 4 Troubleshooting 1 UTA appears to be dead the ou
13. red direct current and should stay at least 2 volts above the full scale output voltage 3c Is the sensor is close to a strong electromagnetic field such as a halide lamp or a refrigerator motor or other AC power equipment If so try to reroute the sensor cable or run the sensor cable inside a grounded metal conduit Avoid running the sensor cable in the same conduit as AC power lines 3d Occasionally oscillations can arise due to reactive loading on the signal cable Placing a 0 1uF capacitor between the signal terminal and the common terminal at your data logger input will usually suppress the oscillation UTA re calibration The jumpers in the UTA select certain popular values for the transconductance gain If you want to set an intermedi ate value of gain it is possible to do so The diagram below shows the location of the gain adjustment trimmer Use a precision current sink as the input signal for the amplifier and an accurate 4digit DVM to read the amplifier out put voltage Set the output of the precision current sink to the desired the full scale sink current Adjust the first stage gain trimmer to give the corresponding full scale output For example to calibrate for a Quantum PAR sensor we standardize with a 16 0 microamp input current and a 5 0 volt output voltage The adjustment range is 20 of the fixed gain value rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www
14. reset preset output for 1 2 5 or 10 volts no charge special output ee ee eg preset output range for special value add 15 HOBO ee ee ee ee ee ee eg special to run from 2 5 volts supply 0 2 5 volt fs output add 10 io RE EE no enclosure amplifier electronics only subtract 15 Example 1 UTA 200 5 UTA pre configured for 0 to 5 volt output from LI 200 Pyranometer price 105 ea Example 2 UTA BNC 190 1 UTA pre configured for 0 to 1 volt output from an LI 190 Quantum PAR sensor with BNC input termination price 115 ea rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com 1 The following instructions are provided to assist you in the installation and operation of your amplifier While we have made every effort to protect the amplifier from faults improper installation or misuse may result in incorrect readings or at worst failure of the amplifier Please read the manual in its entirety before connecting power to the UTA If you have guestions about the UTA or any portion of this manual please contact EME Systems technical support between the hours of 9 00 AM to 5 00 PM PST at 510 848 5725 or 510 848 5748 fax You may also post your questions to us by e mail on Internet at address info emesystems com Configuring your UTA The first step in using the UTA is to configure it for the LI COR sensor and output voltage scaling you wish to use You may have ordered your UTA pre con
15. times the multiplier printed on the calibration tag that accompanies each individual LI COR sensor multiplied by the UTA s transconductance gain uAmp per Volt Refer to the calibra tion tag on your LI COR sensor for the multiplier for your particular LI COR sensor Drop the minus sign from the multiplier This is your sensor conversion factor Light Level UTA output sensor conversion factor UTA transconductance gain Please refer to the table below to find the UTA transconductance gain corresponding to their positions Table of LI COR sensor types Vs Transconductance gain for various jumper settings Rev D JP2 1 1 Volt fs JP2 2 2 Volts fs JP2 3 5 Volts fs JP2 4 10 Volts fs Example calculations Example 1 Suppose you will be using your UTA in conjunction with a Quantum PAR sensor LI 190 and that the Quantum sensor calibration tag states a multiplier of 148 5yE m2s per pA Suppose your data logger has a full scale input of 1 28 volts You choose the 1 0 volt output setting for your UTA with a transconductance gain of 16 67 HA V 1st column 1st row in the table The conversion is light level in UE m2s UTA volts 148 5 16 67 UTA volts 2475 5 UE m2s per volt A 0 836 volt output signal would indicate 2069 5 UE m2s Example 2 Suppose you will be using your UTA in conjunction with a Pyranometer sensor LI 200 and that the Pyranometer sensor calibration tag states a multiplier of 9 8 Wim2 per pA Su
16. tput voltage is stuck at zero or full scale regardless of light level Things to check la Check supply voltage and polarity at the red and black terminals of the UTA circuit board 1b Check the sensor polarity make sure that the center conductor on the sensor wire is connected to the white ter minal and the outer shield wire is connected to the black terminal on the UTA input lc Check the screw terminal connections make sure all of the wires are clamped solidly in place The sensor wire should be clamped in the terminal not loose underneath it The center conductor of the sensor wire is delicate be sure it is not broken ld If you are testing the unit on a bench indoors you may have to move it very close to an artificial light source to get aresponse Light levels indoors are much much weaker than sunlight Be sure the protective red cap is removed from the sensor le Check if the sensor and gain selecting jumpers are in place oriented properly and seated firmly 1f Has there been a lightning strike in close proximity Although the UTA is protected against excess or reversed power supply voltages it can not be expected to survive catastrophic extremes 1g Check for evidence of water entry into the cabinet In regions of extreme humidity or precipitation it may be wise to place a dessicant such as silica gel inside the UTA s cabinet 2 Amplifier seems to be responding to light but the output seems too low or too high Things to check
17. xactly 4 0 volts when the solar input is 2000 wE m2s Note that the sensor output when the solar radiation is 2000 uE m2s will be 10 667 microamps 2000 187 5 One way to do the calibration would be to apply a current of exactly 10 6667 microamps to the UTA input and then adjust the trimmer in the UTA to give an output of 4 0 volts It may be more convenient to use a standard current sink say 10 microamps and then set the output to 3 750 volts 4 10 10 667 It may be necessary to add an extra resistor to the jumper block in order to achieve calibrations that are far from the center values Please contact EME Systems for assistance Alternatively a calibrated light source such as LI COR s 1800 02 Optical Radiation Calibrator can be used to match a LI190 and LI210 sensor to the UTA Place the sensor in the calibrator and adjust the first stage gain trimmer to match the desired voltage output Or you can use one recently calibrated LI 1xx as your standard for calibrating others of the same type given a stable light source e LI COR recommends that all LI XXX series sensors be returned for re calibration every two years This will ensure proper calibration and compensate for the effects of aging and degradation on the sensor rev D 2004 EME Systems 2229 Fifth St Berkeley CA 94710 510 848 5725 fax 510 848 5748 www emesys com 6 UTA Polycarbonate Enclosure Physical Dimensions UTA BNC 2 Holes 0 175 ID Screws Supplied se
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