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motor.txt
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1994-08-18
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2KB
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34 lines
MOTOR SPEED CONTROL UNIT
────────────────────────
+12...15V───┬────────────────┐
│ │
47R ███ │ C
1/2W███ / BD649 or equal
│ B │/ NPN Darlington transistor
1K ███<──────────│
speed ███ │\\
adjust │ \\ E
potentiometer │ two diodes │ to tape recorder
│ 1N4007 │ motor + terminal
└─>├──>├──────────┴───────────────>
(remove internal speed
control unit from motor
case). Connect motor -
terminal to ground)
A motor with centrifugical mechanical internal speed control does not work!
If RFI problems exist, add 1nF ceramic capasitors
between base and emitter and also between collector and emitter.
You should get typically about 70 RPMs (or more) at the beginning of the
tape on the take-up (smaller) C-cassette reel, when recording. This makes
1000 to 1200 LPM speed decodable with the tape recorder.
When playing back, the speed should be able to go down to around 5...10
seconds / round on the take-up reel.
This is just my quick and easy proposal to make the speed control work.
There are numerous other, less easy ways to do it, just don't believe
the pulse control gives any better results without a feedback from the motor,
than any other type of DC control without feedback.