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Spepper Motor control system

Hi Guy's

Wonder if you can help.

I am looking for a simple solution for controlling a small stepper motor.

The controlling input will be a variable frequency from a Hall sensor.

I have looked for a control board with a potentiometer or dipswitches to scale the output speed of the stepper motor, but no luck.

Can anyone suggest a board that accepts frequency input and has some scaling method, or a combination of boards that will achieve this.

Many thanks

Hugh

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Birdmun,

Thanks very much for the suggestion.

Would the circuit provide a fixed % change to the input frequency, or would it provide an offset frequency?

E.g. a 53% trim change would be applied to all the input frequencies.

This is close:-  http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=290703100276&ssPageName=ADME:X:AAQ:GB:1123

With JP1 removed it accepts PWM input but the trim buttons control direction.

With JP2 removed the buttons increment and decrement.

Ideally I would like a trim pot to scale the frequency change to the driver circuit.

I can make gross changes to the input frequency, so that it is within a range, just need to find a way to trim things.

Thanks

Hugh

Maybe a circuit like is shown here, http://www.instructables.com/id/Easy-to-build-CNC-Mill-Stepper-Motor-and-Driver-ci/ will work. It has a Step and Direction with an optional Enable. I would ignore, not include, the Enable and tie the Direction HIGH or LOW, then feed your frequency into the step "pin".

In the end, my best suggestion would be for you to base your circuit on some form of Step/Direction stepper driver. Feed your frequency into the Step and pull the Direction either HIGH or LOW as you wish for stepper direction.

Just be sure to pay attention to what the max frequency the circuit can work with. If you try to send a 20kHz pulse into the Step pin and your circuit/chip can only handle 5kHz, you will at best get a skittish stepper, and, at worst get an immobile stepper.