Steve and Eric,

He was talking about driving a stepper motor.
Of course you can drive a DC motor using PWM at 50kHz.
I don't think that a Stepper motor would respond to pulses at 3kHz.

Also it appears that Prahlad is not driving the motor directly, but through a driver board which would also have restrictions on how fast you can pulse CW or pulse CCW. I don't think the ULN2803 is needed in this application, the driver board probably accepts TTL signals, so he could drive it with the optocouplers.


Jacob