Two potentiometers on a pulse width modulator

[Madsalts]

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]

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

 

[Madsalts]

sadly, I don't. This is it, though:

http://www.ebay.com/itm/10-50V-60A-...012?pt=LH_DefaultDomain_0&hash=item4623c0fd34

 

[signalman72]

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

 

[Harald Kapp]

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]

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]

[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]

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]

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