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Tom Schindler
12-11-2001, 06:52 PM
Does anyone know of a speed controller that will accept an analog voltage (0-5V) as its input??

Thanks

Tom

Joe Johnson
12-11-2001, 09:03 PM
If I recall correctly, the speed controllers are expecting a short pulse every 20msec or so. They accept a relatively wide range of base frequencies. The important thing is the pulse width. I believe that a 2msec pulse width is full stop. 2.5 msec pulse is full forward and 1.5 msec is full reverse.

I am going strictly from memory so don't quote me. The idea is right but the absolute numbers are probably wrong.

In any case, this is not too hard to make a "555" timer circuit that would turn a voltage of 0-5 into the right pulse train. I suppose that there are even custom IC's that would do it for you. Better yet, if you have an extra Stamp2 laying about you can fairly easily make it do the interface for you.

Good luck,

Joe J.

Tom Schindler
12-12-2001, 04:35 PM
Joe,

Not sure if you misunderstood me, i was not planning on running 5 volts into a victor :)

The PWM signal has a 17 ms period with a pulse width from 1-2 ms. A pulse of 1.5 ms is considered neutral.... I was wondering if anyone knew of different kind of speed controller that would accept this a 0-5v input, or, as Joe pointed out.. a way to transfer 0-5V into the correct pulse

ChrisH
12-13-2001, 12:20 PM
I don't know about speed controlers, but we used to control temperatures with a 0-5v circuit. Most equipment has gone to 4-20mA. At least then you know if the signal gets lost. I would assume there would be something out there if only for replacement parts on existing equipment.

ChrisH

Mike Betts
12-13-2001, 04:26 PM
Tom,

There motor drives for DC brushless motors which take 0-5V, 0-10V and/or 4-20mA inputs.

I had inquired with innovationfirst about an analog input (for a past project we were working on) and they had indicated that, yes, they could do it (OEM basis).

However, after I had a bit of time to think about it, I came to the conclusion that a digital interface would be more noise immune.

In the end, I went with a DC brushless motor with a conventional motor drive and 4-20 mA input. It was much more versatile for the rapidly changing requirements of that development effort.

Now, back to your issue... What's the size of your load? If it's small, a DC/DC converter "brick' with a variable output may do the trick. They have current limiting and everything...

Bottom line, the IF speed control is a pretty good package and I don't know of anyone who makes a 0-5V input AND you already know a lot about the IF controller. I would agree with Dr. J... a 555 timer is a piece of cake. You can buy them at any Radio Shack.

Mike