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[on:]

For an out-runner to my HEMTT project, I want to power this dual-motor ( http://www.robotshop.com/tamiya-double-gearbox-70168.html ) with a cheap/small arduino, using Bluetooth via amarino, and stick it in this -> http://www.robotshop.com/tracked-vehicle-chassis-kit-4.html , then make a simple sheetmetal hull (the math is easy) so it can float.

Basically, making an ARGO type vehicle. I'd be running it off a 7.2 NiMH pack.

How would I run the low-voltage motors with the arduino? I assume the arduino will be fine running off the 7.2, it's stepping down to the 1.5 for each motor I'm not sure about. Each motor pulls 0.66 amps.

[Reply #1 on:]

One way to do it would be to run the motor at the full battery voltage but to use PWM to limit the average voltage to the motor. So for example if you ran it at 7.2V but at a 20% duty cycle it would be the equivalent of giving the motor 1.5V, even though you are giving the motor 7.2V peak. This will not harm the motor.

[Reply #2 on:]

That is what I was thinking, would I notice any surging as a result of doing this, due to the very long duty cycle?

What would be the easiest way to do this, as far as physically driving it? I dont know of any ESC's rated for 1.5V, would I have to use a H-bridge shield or ???

I'd like it to be reversable as well...

I'm basically trying to make a cheap version of this -> http://www.robotshop.com/dfrobotshop-rover-tracked-robot-basic-kit-3.html

[Reply #3 on:]

You can crank the PWM frequency up, 20% at the normal 500Hz (ish, I think it's 492 or somesuch to be exat) may make interesting noises.  If you wind it up to 32kHz you shouldn't have any issues at all.  That does assume that whatever switching you're using can run that fast of course.