PWM Circuit

[zerotact]

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

 

[shortbus=]

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

 

[zerotact]

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

 

[MaxHeadRoom78]

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.
Max.