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PWM Circuit


New Member
I have a small lathe that went down and I need it to work--the board may be fried and im waiting for mosfets to see if thats the problem. meanwhile trying to pulse a tread mill motor controller to run the motor using a -555--astable- timer circuit--the circuit is working and the 20 HZ signal is triggering the board to put out 84 vdc as it should, but the motor wont work. I hooked a 12 V car battery directly to the motor leads and it spins right up and runs smooth. Slow but it runs. Why will it run on the 12 v battery--but not the dc coming from the motor controller. The motor is rated for--130 Vdc--3A--please help


Well-Known Member
What is the source of DC when using the PWM? You didn't mention it or what your switching components are in your post.


New Member
homemade bench top power supply using an ATX computer power supply--I used the 9 Vdc out but it could be 12 or 5---does not matter as long as im putting out a 20 hz wave to trigger the motor controller


Well-Known Member
This must be a MC2100 board?
There is a LED that indicates the status of the signal and the board.
Do you have the correct series resistor into the board to limit the opto current?
I have built a pic 12F based one with stop start buttons for this board.

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