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Terry

Speed Controller

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Hi all, I want to drive a camera platform left and right using a standard r/c channel and the platform is driven by a 6v 0.5A geared motor. I want equal speed control in both directions and no setting up before use, just switch on and go. Say 1.5ms pulse for off and 1.0ms and 2.0ms for full power each way. Im thinking of a pic based solution at the moment and have a few ideas but I dont want to wast time on it if its already been done. Anyone done it ?

Terry

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Why not use the electronics from a hi-torque R/C servo? It should work in your app.

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Terry, how soon you need it? I have some tiny pic boards I could modify to do what you are looking for from another project. Are you going to use something like a 3 way switch??

Matt Klarich

Email: mklarich at stoneflyers.com (I put at in instead of @ for spam bots)

Edited by mklarich

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Hi Matt, no I plan to use a normal stick channel, Im not in a hurry though. I have been looking at some of the pic designs for model boats but they all seem to use relays for reversing. I dont have a spare hi torque servo so its not going to be cost effective for me, plus I would like to build a few. Its a project I will have to do as I keep finding applications for small reversable speed controllers. hard to believe I will be first !

Thanks, Terry

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You can use servo's PCB to drive your motor if you don't like the motor that came with the servo. 0.5A is not that high, may be regular $15 servo circuit will be enough. I don't believe there is a cheaper solution out there.

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The other thing I forgot to say was that when I have used servo pcb in the past its been hard to stop the motor from drifting as the dead band is very small.

Terry

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You can usually increase the deadband by changing a resistor. Just look at the data sheet to the servo amp IC that is used in the donor servo and go from there.

Using a PIC to control a motor will require a bridge amp and other parts. Overall costs will probably be close to a low end servo (under $10), so the savings aspect is probably not going to be realized. The nice thing about using a servo's board is that it is nearly ready to use. However, I totally understand that part of the fun is designing this sort of thing, so cost is often not an issue.

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Or you can simply use a small speed regulator with reverse. I don't know what you have at your place, but we've used many times cheap Graupner 6A regs for such purposes. They work perfectly.

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In the end I just could not resist it, Ive written a program for a pic !

Thanks to everyone for their ideas though.

Terry

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