Variable Speed Stepper Motor

Hello Everyone,

I am looking for some help to make a controller to drive a stepper motor using a potensiometer. I want to be able to vary the speed from 0 to 100rpms or however fast the stepper motor will go.  

I have a bi polar stepper motor that I am using. 

If anyone could help with this it would be great! 


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pfred25 years ago
Do you mean like this?

I did it with a 555 timer generating the step pulses. Pretty easy really.
MCrous pfred23 years ago

hi, you wouldnt happen to have a diagram of this handy?

pfred2 MCrous3 years ago

This is the generic astable 555 timer schematic

You want to stick to 5volts input for a logic signal output. I found a 470pF capacitor on the threshold worked well for me. For the resistors use 2 potentiometers (100 Kilo ohms or so) and adjust them for the speed you want. One between pin 6 and 7 will adjust the pulse width, and the other the the frequency. Sometimes it helps to use a bigger timing capacitor (about one μF) and an LED (use a 330 ohm current limiting resistor to drive an LED at 5 volts) and make the LED flash, before you move onto trying to drive the step input of a stepper motor drive. Once you see you're generating a good pulse train then you can move onto the smaller capacitor for a faster stream of pulses. Then once you get things dialed in just turning the 8,7 potentiometer will adjust your motor's speed.

caitlinsdad5 years ago
Easiest way I know of is to use a microcontroller like an arduino which can pump out the PWM digital control for servo/stepper motors.