# Large motors

Forgive me if this topic has been asked before. A quick search didn't come up with anything.

I'm building a prototype for a solar power plant. I need to move fairly heavy mirrors to track the sun. From what I can tell, the Arduino will work perfect for this, except the motors I need to use require more power than hobby motors. From the little I understand about electronics, it seems that large current run through an arduino would burn it out.

Can someone point me in the right direction to create something like the available motor shield(s), but one that works for larger motors (1/2 Hp - 1 HP stepper motor)?

I'm still trying to figure out how much torque I need, so I don't know the exact size of the motor yet. Thanks in advance!

Steve Nelson

Hi Steve,

The motor driver method will be dependent on the motor you choose. Can you post some information on the specs for the motors you are considering?

Hmmm I was afraid you'd ask that! How about one of these:

http://www.kelinginc.net/SMotorstock.html

Again, I'm not sure if this is the right size, but let's go with the biggest one on that page:

KL42H2150-42-8B (Dual Shaft) Specification Rated Current: 6A, Rated Voltage: 8.4V (in Bipolar Parallel)

Does that help?

Steve Nelson

That motor requires more current than IC based driver typically used, such as in this tutorial http://www.arduino.cc/en/Tutorial/StepperUnipolar

But the principal should be similar, you would use discrete FETs or darlingtons instead of the driver chip

I presume you have looked at the stepper library documentation: http://www.arduino.cc/en/Reference/Stepper?from=Tutorial.Stepper

To be honest, I haven’t looked at much of anything yet. I just learned what a stepper motor is yesterday. I’m trying to figure out the right questions to ask. The logic in my head is telling me that I needed one power source for the arduino and a second, much larger, power source for the motor. Then the arduino somehow needs to control that big power source. Or… something like that.

Steve

Your definitely on the right track. The arduino will be switch the high power source to the motor windings using high power switching semiconductors. But it could be worthwhile you doing a prototype first with one of the low power steppers in those links. That way you can get things going by duplicating the stepper tutorial and develop and test your software before connecting up the high power stuff.

Have fun!

Another option is to use a separate driver so that you can use the arduino for more.
With the following, you can get by with only using 2 of the arduino’s digital outputs.

http://greta.dhs.org/EasyDriver/

You will still have to figure out how to handle the amps though.

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