Audio amp & sig gen to control stepper motors?

[HuntMike79]

I'm a bit clueless about stepper motors, but I was thinking would it be possible to use an audio amp to amplify the sine wave needed to control these stepper motors or would it not work? The wave needed could be generated by the computer and out thru a soundcard...

Anyone tried it?

[moonrock]

usually, audio amplifier is voltage source. to control steppermotor you need to create sin/cos current in windings by current source.. therefore, you can't using amp without modifications.

[HuntMike79]

usually, audio amplifier is voltage source. to control steppermotor you need to create sin/cos current in windings by current source.. therefore, you can't using amp without modifications.

I was just curious really... It does seem 99% of audio amps are voltage limited as opposed to current limited, I think the best thing is to use proper controller circuit. Thanks.

[Sparky_NY]

It wouldn't work for a few reasons. First, the stepper motor needs square wave drive signals and the audion generator is sine wave. Next the audio generator wouldn't supply anything even close to the 2-7 amps typical for a stepper motor.

[budP]

"First, the stepper motor needs square wave drive signhihals "

This is not a true statement. Look at the output of a Geko drive with a scope, go to the Linistepper site and look at the drive scope images there. I think that there are a lot of drivers for steppers that are PWM

budP

[Sparky_NY]

"First, the stepper motor needs square wave drive signhihals "

This is not a true statement. Look at the output of a Geko drive with a scope, go to the Linistepper site and look at the drive scope images there. I think that there are a lot of drivers for steppers that are PWM

budP

True. The drive would "try" to output a square wave which wouldn't be possible due to the inductance of the motor. Increasing the voltage would help "square" it up but it still would be quite rounded. In theory you would want a square wave, in the real world it would be quite rounded and look more like a sine wave because of the inductive load being driven.

[vger]

Many years ago I built an over engineered circuit to drive a stepper with sin/cos. I took 2 EPROMs (1K X 8) and burned sine and cosine waveform values in them. Fed the data outs of the EPROMs into 2 8 bit D/A converters. The analog out's of the D/A's went to a pair of home brew push/pull amps. The address lines of the EPROMs were fed from an up/down counter chain 10 bits long. The speed was limited by the conversion rate of the D/A converters but the steppers ran smoooooooooooth.