Is this a goeed/Decent/Bad, Controller

[thuffner3]

I'm looking to build a new machine.
Is this controller worth the $150.00 plus I've seen it sell for?

Recommendations?

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEBWA:IT

[anoel]

Note in the text that the baord requires external ballast resistors. It's not a "Chopper". Just thought I'd point that out so that you would not be disappointed when you found out.

[thuffner3]

I've no clue regarding chopper drives, can you enlighten me a little.

Neil

[ballendo]

Hello,

A chopper is like putting a dimmer switch between the motor and the controller/driver. The "dimmer"/chopper turns the power on and off (very quickly!) to maintain some average value, so your motors don't overheat.

The board shown is called an L/R drive. It uses big resistors to "waste" the extra power as heat, so the MOTORS don't overheat.

Why is there any extra power in the first place? Because as a motor spins it becomes a generator too. The voltage it makes is called Back-EMF and works AGAINST the amps trying to get IN...

But if we raise the voltage(remember voltage is the "push" of electrons, and amps is how many are being pushed), then the motor will run faster. Problem is, when we stop turning, now there's too much electircity about.

Which is why we have things like L/R drives(the old way;very inefficient), and choppers (the new way)

Hope this helps,

Ballendo

P.S. Sometimes you will see the term PWM instead of chopper. They're the same principle, under two different names.

[FRAMEDNLV]

I have a question about the driver board. Say you have a 6V 1.5A motor. And the driver board regulates the amps to 1.5 (PWM Constant-Current Motor Drive). Do you still need to compensate for the limits of the motor voltage when using a 12-24V power supply?

Chris

[ballendo]

Chris,

If the curent is being controlled, you don't have to worry about the voltage... (within reason, which is 4-10 times the motor rated volts for L/r drives and up to 25x for choppers.)

Ballendo

Originally posted by FRAMEDNLV I have a question about the driver board. Say you have a 6V 1.5A motor. And the driver board regulates the amps to 1.5 (PWM Constant-Current Motor Drive). Do you still need to compensate for the limits of the motor voltage when using a 12-24V power supply? Chris

[FRAMEDNLV]

Ballendo,
Thanks. That is exactly what I was wondering.

Chris

[pack rat]

ballendo, nice explanation, I knew it was a better drive but I did not know why. Thanks, Chris

[FRAMEDNLV]

Ballendo,

That is exactly what I needed to know.

Thanks,
Chris