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Two potentiometers on a pulse width modulator

Madsalts

Sep 25, 2014
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I have a pulse width modulator with a dual-ganged potentiometer. I've seen other PWMs with two potentiometers, rather than the single dual-ganged. What two parameters are controlled by the potentiometers? I'm using mine on a trolling motor. If I were to decouple the parameters by using two pots instead of one, what would the effect be? Would this be desirable?
This isn't a situation where I'd be finding one ideal pulse width and sticking to it. I'd be adjusting this to speed/slow the motor. Thanks.
 

Arouse1973

Adam
Dec 18, 2013
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My first thoughts are to control the mark and the space durations, but not sure without a circuit diagram. Do you have a circuit diagram or can you link to a similar one.
Adam
 

signalman72

Jan 26, 2014
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Well, it appears that one set is being used as an adjustable voltage divider and the other as an adjustable resister.
 

Harald Kapp

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Nov 17, 2011
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A standard PWM doesn't require two potentiometers - unless you want to control mark and space independently (Adam's post #2), but in this case you'd like to have independent potentiometers, not a coupled one.
.
Are you sure the second part of this potentiometer is a potentiometer? There are only 2 wires coming from this part. It could be a switch to completely turn-off the controller in the lowest setting.
 

signalman72

Jan 26, 2014
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Ah, that makes more sense! Id nearly forgotten about those switch/pot combos. They were very popular on those little pocket "transistor radios" when I was a kid.
 

poor mystic

Apr 8, 2011
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[QUOTE="Are you sure the second part of this potentiometer is a potentiometer? There are only 2 wires coming from this part. It could be a switch to completely turn-off the controller in the lowest setting.[/QUOTE]

Harald's conjectural switch certainly is in the power supply.
 

Madsalts

Sep 25, 2014
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Thanks for the replies. I'll have to mess around with this. I might decouple the two, since it might be useful to have a killswitch. Furthermore, I can actually find a waterproof pot, whereas I can't find a waterproof dual-gang pot or a waterproof pot/switch combo.
 

Minder

Apr 24, 2015
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I agree, if you look close at the pot rear side, there only appears to be two outer terminals. (switch).
M.
 
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