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[on:]

I'm successfully running an Astrosyn Miniangle Stepper 23Lm-C004-55.
Arduino Uno board, Adafruit stepper shield.
I have a 12v DC 7.5Ah gel battery as my power source to the shield.
The 5v USB supply from the Uno does not provide enough torque.
I'm planning to use this setup to drive a telescope equatorial platform.

The stepper motor gets very hot after a while.
The motor is a 6.0 v/phase 1.2 a/phase unit

Questions...
Should I reduce the voltage to 6v ?
How would I go about doing this ?
Can I achieve this on board the shield ?
Or do I have to buy a regulator ?

Thanks

Chris

[Reply #1 on:]

The only reason you would drive the motor over its 6V rating (which will result in its 1.2A limit) is if you want more speed from the motor.

If you do drive it over its 6V rating them you must prevent it from passing its 1.2A limit. You can do this with a "chopper" driver or by adding high wattage resistors on the wires to the coils of the motor.

Take note that the chips on your Adafruit board are limited to 1.2A. If you have not blown the chips already then it will happen soon.

http://www.pololu.com/catalog/product/1182 is a very popular driver and has current limiting capability. Your stepper has 6 wires so it can be driven in a bipolar mode as this driver requires.

[Reply #2 on:]

Thank you Chagrin,

I've ordered one of the Pololus.
Looks as though I'll have much more control  over the motor.

Thanks again,

Chris

[Reply #3 on:]

What do you mean by "very hot" ?  Typical stepper motors are fine up to ~150 F.  If you can touch it comfortable, it's not doing any damage.