Datong D70 Manual + Service
Contents
1. SUAGKINN 02d 13dON DNE CUR nn 5091191 5831131 404 SO 530795 OL INIT 300 Sid OL HOLSIS3H A 016 7 OL L Nid Wows SHOLSISSY 17 dO asn aH aainoas INOS 7 79078 221 38LZ0v09 921 38620709 821 521 29 1072 tl 810009 0121 EDI 621 221 JANGJI LOI LON 38 LSNW 0131 2 A S 01 5809 SW2VP 30 ON AN Uzv gt 21 UO 12591 14 ii zee CH W a AV m z ey DA 9 lt WOL 9291 gt a ST AMBLLVS A 6 Wr 022 2 03345 B 9L Pd 2 MOVP 350 TVNSINI 51309 SDI TTY OL 8 15 A Sb2. for the next character is required a brief positive pulse is generated by Q4 which powers up the PROM Information at the PROM s outputs pins 1 2 3 4 5 6 7 9 is then latched into IC5 and IC6 by a strobe pulse from pin 10 of IC3a The strobe pulse is slightly delayed from the power up pulse by R8 and C5 The strobe pulse is very short mainly determined by R9 and input capacitance of pin 10 of IC2b H nformation captured by IC5 determines the length of the next character Information stored in IC6 shift register determines the dot dash sequence A low into the preset inputs of IC6 signifies a dash and a high dot Characters are read out at a rate determined by the main timing oscillator ICla and b under the control of the SPEED control square wave from IClb is converted into a single dot plus space one cycle of the clock or a dash plus space two cycles of the clock by IC2a and IC3b When pin 4 of IC2a is low dashes are produced and dot when pin 4 is high During the read out of a character IC5 counts up by one for every dot or dash from the number originally loaded into it by the strobe pulse When th number reaches binary eight pin 2 goes high This turns off the audio output via R3 and after a delay determined by VR2 and causes D on IC2b to go high Furthermore pin 4 of IC2a is forced high via IC3c so that a silent dot is produced At the end of this silent dot Q
3. of IC2b goes high and data for the next character is called up from the PROM The silent dot in effect constitutes the inter letter space 3 time units while the extra delay if any selected by VR2 and C6 adds to the inter letter space After five interword spaces have been counted by ICA its pin 2 goes high and forces the production of a silent dash via IC3d It also presents a high at pin 3 of IC5 during the load pulse and this transfers immediately to pin 2 after the silent dash thereby causing the letter to be followed immediately by a silent dot two together constitute the seven time unit interword space When letters are being produced the combination IC8 IC9 a counts cyclically down in binary from 26 to 1 state zero exists only for the time req res ill Wit dow to uired for IC8 and IC9 a to self reload to 26 Any fault in this etting will cause adress zero to be accessed and this will produce the egal character da dah dah dah h number generation IC9 a remains held with pin 1 high and IC8 counts n from 26 to 17 the never normally accessed address is 16 If due a fault it is accessed the illegal charcter produced is dah dah dit dit dah In wit In out Typ the numbers mode D7 D6 and D5 R12 ensure that IC5 is allways loaded h binary 3 The character lenght then being 8 3 55 the mixed mode IC9 b extends the adres
4. DATONG ELECTRONICS LIMITED MORSE TUTOR An instantly available source of precision Morse for training purposes at all levels of skill ee 4 4 LETTERS 2 r Ws Civi MIXED L NUMBERS aft MORSE TUTOR THE REVOLUTIONARY NEW WAY TO PRACTICE MORSE CODE RECEPTION AN UNLIMITED SUPPLY OF PRECISION MORSE AT THE TURN OF A SWITCH PLUS BUILT IN OSCILLATOR FOR SENDING PRACTICE e Sends a continuous stream of precision Morse in five character groups which never repeat e Variable speed and variable delay between characters for optimum learning efficiency e Letters only numbers only or mixed e Built in tone oscillator for sending practice key required Earphone socket for private listening e Eleven IC CMOS circuit for long internal battery life PRECISION MORSE The Dantong Morse Tutor sends a continuous stream of precision Morse Code in random five letter groups Its sending is impeccable it never repeats and it never tires You can select letters only numbers only or letter and numbers mixed at the flick of a switch OPTIMUM LEARNING TECHNIQUE Best of all not only can you vary the basic sending speed from 6 5 to 37 words per minute you can also increase the delay between letters from the correct value 3 dot periods to a maximum of over 3 seconds This delay facility means that right from the start you can learn each letter and number as it ought to be learnt that i
5. MORSE WITH THE DATONG TUTOR The key to learning Morse is to learn each character as a complete sound pattern not as a set of individual dots and dashes It is important also to be able to receive Morse reasonably well before you begin to practice sending Start with Morse Tutor set to between 8 and 12 words per minute but with maximum delay between characters This way you learn the correct rhythmic sound of each character in the code list As you become familiar with the code gradually reduce the delay between letters Ideally the speed should always be slightly faster than you are able to read comfortably Many short practice sessions are much better than few long ones Take advantage of Morse Tutor s portability and personal earpiece to snatch as many practice sessions as possible You can learn Morse with minimum disruption to your normal activities by using time which would otherwise be wasted for example while travelling to and from work Once you have learnt the basic code and can recognise the characters from memory your main practice should consist of writing down the output from Morse Tutor Use longhand right from the start rather than printing otherwise as you progress your ability to copy Morse will outstrip your speed of writing It is also beneficial to listen to Morse Tutor s output even at times when you are unable to write it down This helps you to recognise the tune of each character and to split up the continuous stre
6. am into separate characters Do not be discouraged if your progress appears to come to a halt at various stages This is quite normal and in fact is normally a prelude to a significant jump in receiving speed When you have reached a speed of about six words per minute you are ready to begin sending practice Simply plug a conventional Morse Key into the KEY jack on the rear panel of Morse Tutor This disables the automatic sending circuitry and the unit will produce a tone whenever the key is pressed the key should close a contact when pressed INTERNATIONAL MORSE CODE Morse code comprises a stream of dots and dashes If the duration of a dot represents one time unit a dash is three units the space between dots and dashes within a character is one unit the space between letters in a word is three units and the space between words is seven units When the DELAY control is set to the CALIBRATE position fully clockwise Morse Tutor produces Morse with the above timing and in five character groups As extra delay is introduced between letters the delay between words becomes just twice the delay between letters Timings within each letter are determined only by the SPEED control The basic Morse characters are given below in the form of dots and dashes When saying them either aloud are mentally use dit to represent a dot and dah for a dash Letter for example is pronounced dahdidadit It is important to learn the code
7. as sounds not as visual patterns SPR GA md rm uU ue NK MB SCHEV TATO N O 3 AUDIO NOTE The frequency of the audio tone can be altered if desired by adjusting the preset potentiometer labelled NOTE on the printed circuit board To open proceed as described under battery replacement BATTERY REPLACEMENT When Morse Tutor produces all dots or all dashes the battery should be replaced First switch off the unit Then remove the top two screws on both front and rear panel and lift off the upper half of the case The battery can then be replaced Take care to observe the correct polarity WARNING When replacing the panel screws take care not to strip the threads by overtightening DATONG ELECTRONICS LIMITED Spence Mills Mill Lane Bramley Leeds LS13 3HE England Telephone 0532 552461 ERVICE INFORMATION MODEL D70 ep THE CIRCUIT AND SERVICE INFORMATION SUPPLIED IS CONFIDENTAL AND FOR USE BY DATONG AGENS ONLY Refer also to circuit diagram data sheet PCB layout Dismantling Remove the eight screws holding both front and rear panels This allows the top half of the case to be removed remove the PCB remove the four screws through the PCB Leave the panels and controls soldered to the PCB leads Circuit description A noisy clock oscillator 10 b clocks the adress counter IC8 9 for the PROM IC7 at a random rate When informaton
8. s counter by an extra bit and its put determines whether the next character is to be a number or a letter ical faults The a b following faults have occurred at various times in the past Accidental unsoldered feed through pins or IC top pins can cause illegal letters to be produced Some specimens of IC10 have resulted in random clock pulses which are too narrow to clock IC8 correctly This results in the illegal addresses 0 and 16 being accessed The pulse train at pin 11 of IC10 b should look symmetrical about 2 5 volts If Q4 does not turn fully off Q3 can remain slightly on When VR2 is set to a high value this can cause a very long even an infinite delay to occur as charge leaks through Q3 faster than VR2 can supply it R20 was added later to avoid this Other points a b Reducing Cl allows faster sending speeds to be achieved Adding a jack to the rear panel to allow an external supply to be used can short out the regulator if an uninsulated jack is used This is because the back panel is at 5 volts If this happens the TTL PROM will probably be damaged If an output for a tape recorder is required from the earphone jack a resistor say 100R is required to maintain a DC path for collector current in Q2 97299 ZEGO sUoudajo puejBu3 2187 Aopueig iti SIA eoueds 5498
9. s with the dots and dashes within a letter fast enough to form a complete sound pattern but with a long delay between each letter As you improve you simply reduce the delay between letters USES YOUR TIME TO BEST ADVANTAGE Skill at Morse reception only comes with practice and this uses up valuable leisure time With Model D70 you can make every minute count because you can tailor the level of difficulty exactly to your own ability Moreover you are no longer tied to someone else s timetable Morse Tutor is available at any time day or night so you can snatch a few minutes practice whenever it suits you This way your practice sessions can make use of time which would otherwise be wasted while travelling for example ALWAYS FRESH Unlike tapes and records whose sequence becomes familiar surprisingly quickly the Morse Tutor never repeats the same sequence twice This means you don t have to ration the supply to avoid wasting it LEARN WITH CONFIDENCE Morse Tutors calibrated controls mean there will be no doubt about when you are up to examination speed With today s examination fees it pays to pass first time AFTER THE MORSE EXAM After Morse Tutor has helped you to pass the Morse Exam it will painlessly help you to the still higher speeds which are needed to get the full enjoyment from real life operating 15 wide speed range means that even experts can use Morse Tutor to keep in trim or as a refresher course HOW TO LEARN
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