170 lines
6.4 KiB
Plaintext
170 lines
6.4 KiB
Plaintext
BLUE BOX PLANS!
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---------------
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This file will explain the construction, troubleshooting,
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This design will make them last 10 months!!!!!! But
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nevertheless, don'tforget to put in aswitch for on and off. Ok
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let's build the two VCO'S andcalibrate the unit before we get to
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the keyboard construction.
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VCO CONSTRUCTION
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TOOLS REQUIRED
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1 ocilliscope(optional but not req)
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1 Freq. counter (REQUIRED)
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1 Volt meter " " "
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Electronics tools (Pliers, drll, screwdrivers, etc.)
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PARTS
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R1 1.5K RESISTOR 5%
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R2 1K RESISTOR 5%
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C1 .1uf ELECTROLYTIC CAPACITOR 16VDC
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C2 .01uf " " (MYLQR) 16VDC
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C1 2207 VCO CHIP BY EXAR ELECTRONICS
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Remember the above only says VCO#1 but the same is for VCO#2
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R3-R4 150 OHM RESISTORS 5% .
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C3-C4 .1 uf ELECTROLITIC CAPACITOR .
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10VDC .
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P1-P10 200K TRIMMER POT - 20 TURNS DIODES USED IN THE KEYBOARD
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ARE 1N914 TYPE(40 OF THEM) & 13 SWITCHES FOR THE KEYBOARD SPST
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MOMENTARY.
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SPKR YOU CAN USE A TELEPHONE SPEAKER FOR THIS (IT WORKS BEST) BUT
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REMEMBER TOTAKE OUT THE DIODE THAT IS CONNECTED ACCROSS IT.
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IMPORTANT NOTES
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1. DO NOT USE ANYTHING ELSE OTHER THAN A MYLAR CAPACITOR FORC2.
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2. PINS 10,9,8 SHOULD BE TIED TOGETHER AND BE LEFT FLOATING.
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3. ALL RESISTORS SHOULD BE 5%! NOTHING ELSE!
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4. A TELEPHONE SPEAKER GIVES THE BEST RESULTS.
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TROUBLE SHOOTING
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By now you should have constructed the two VCO'S on a bread board
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or anything that pleases you. Check for cold solder
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joints,broken wires,polarity of the battery, etc. Before we
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apply power to the VCO'S we have to adjust the pots for their
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half way travel point. This is done by turning them 21 turns to
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the right and then 10 turns to the left. Do the same for all ten
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of them.
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Now apply power to the unit check to see that you have power in
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the chips by putting the positive lead of your volt meter on pin
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7 andthe negative lead on pin 12. If you do not have anything
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there turn off the unit and RECHECK THE WIRING.
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When you get the right voltages on the chips, connect a diode to
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a piece of wire (look at fig. 2 for the orientation of the diode)
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from round to any pot at point T (look carefully at the schematic
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for point T it is labeled T1-T10 for all pots). You should be
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able to hear a tone, if not disconnect the lead and place the
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speaker close to your ear and if you hear a chirp-like sound,
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this means that the two VCO'S are working if you don't,
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it means that either one or both of the VCO'S are dead. So in
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this case it is always good to have an ocilloscope on hand.
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Disconnect the speaker from the circuit and hook the ocilliscope
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to 1 of the leads of the speaker & the ground from the scope to
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the ground of the battery. Connect again the ground lead with the
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diode connected to it from ground to any pot on the VCO that you
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are checking and you should see a triangle wave if not turn the
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pot in which you are applying the ground to until you see it.
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When you do see it do the the same for the other VCO to makesure
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it is working. (amplitude is about 2VAC). When you get the two
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VCO's working you are set for the adjustment of the individual
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spots.
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ADJUSTMENT
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Disconnect the speaker from the circuit and connect a freq.
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counter (the positive lead of the counter to one of the speakers
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leads that belongs to VCO#1 or connect it to pin 14.
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Connect the negative lead to the battery negative and connect the
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jumperlead with the diode from ground to pot number 1.T1 (the
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first pot number 1 point T1). If you got it working you should
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hear a tone and get a reading on the counter. Adjust the pot for
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a freq. of 1700hz and continue doing the same for pots 2-5
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except that they get different freqs. which are:
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: $$$$$$$$$$$$$$ :
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: $ $ :
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: $ P1 1700hz $ :
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: $ P2 1300hz $ :
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: $ P3 1100hz $ :
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: $ P4 900hz $ :
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: $ P5 1500hz $ :
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: $ $ :
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: $$$$$$$$$$$$$$ :
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Now disconnect the freq. counter from the speaker lead of VCO#1
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or from pin (which ever you had it attached to at the beginning)
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and connect it to the speaker lead of VCO#2 or to pin 14 of VCO#2
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and make the same adjustments toP6-10.:
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: $$$$$$$$$$$$$$$ :
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: $ $ :
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: $ P6 1100hz $ :
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: $ P7 700hz $ :
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: $ P8 900hz $ :
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: $ P9 2600hz $ :
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: $ P10 1500hz $ :
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: $ $ :
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: $$$$$$$$$$$$$$$ :
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When you finish doing all of the pots go back and re-check
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them.
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KEYBOARD
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IF YOU LOOK AT FIG-2 YOU WILL SEE THAT THE KEYS ARE
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SIMPLE SWITCHES. CONNECTED TO A GROUND AND TWO DIODES ON THE
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OTHER END. THESE DIODES ARE USED TO SIMPLIFY THE CONSTRUCTION OF
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THE KEYBOARD BECAUSE OTHERWISE THE DISTRIBUTION OF THE GROUND
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SIGNAL FOR BOTH VCO'S WOULD HAVE BEEN DONE MECHANICALLY. THE
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DIODE WILL GO TO VCO#1 AND THE OTHER WILL GO TO VCO#2. FIG-3
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SHOWS THE ARRANGEMENT OF THE KEYS ON THE KEYBOARD.
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BELOW IS A TABLE THAT WILL HELP YOU CONNECT THE KEYS TO THE
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REQUIRED VCO'SPOTS.
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<------------------------------------->
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< >
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< (-FIG 2-) >
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< >
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<-----!-----!--------!--------!------->
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< ! ! ! ! >
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< TO ! TO ! FREQ ! FREQ ! KEY >
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< POT ! POT ! OUT: ! OUT: ! >
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< ON ! ON ! ! ! >
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< VCO1! VCO2! ! ! >
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<-----!-----!--------!--------!------->
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< 1 ! 06 ! 1700hz ! 1100hz ! C >
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< 2 ! 10 ! 1300hz ! 1500hz ! 0 >
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< 1 ! 10 ! 1700hz ! 1100hz ! E >
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< 4 ! 07 ! 0900hz ! 0700hz ! 1 >
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< 3 ! 07 ! 1100hz ! 0700hz ! 2 >
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< 3 ! 08 ! 1100hz ! 0900hz ! 3 >
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< 2 ! 07 ! 1300hz ! 0700hz ! 4 >
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< 2 ! 08 ! 1300hz ! 0900hz ! 5 >
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< 2 ! 06 ! 1300hz ! 1100hz ! 6 >
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< 5 ! 07 ! 1500hz ! 0700hz ! 7 >
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< 5 ! 08 ! 1500hz ! 0900hz ! 8 >
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< 5 ! 06 ! 1500hz ! 1100hz ! 9 >
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< - ! 09 ! ------ ! 2600hz ! X >
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< ! ! ! ! >
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<------------------------------------->
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REMEMBER THAT IN FIG-2 IT'S THE SAME FOR EACH KEY EXCEPT THE "X"
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KEY, WHICH ONLY TAKES ONE DIODE.
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