Switching between potentiometers

[Drake120]

I want to have a toggle to choose between two potentiometers of different value - do I have to use 3pdt switch? How to wire it?

And, BTW, anyone knows a really good article about switches and how to wire them? I found some stuff there, but there are only practical explanations for specific problems. I'd love to learn some theory so I could find this out by myself.

[frequencycentral]

[AceLuby]

I think you may be able to use something other than a 3pdt switch if your input or ouput is from the same source.

[Minion]

Seems like a neat idea But I don"t understand what purpose it would serve accept if you just wanted to switch between different Volume/Gain settings...??

[Drake120]

For example: one pot for manual setting, second in an external pedal. Or just two pots of different range.

Ace - what kind of switch are you talking about?

And one more not-certainly-about-the-topic question: what kind of wire should I use to connect a stompbox to external expression pedal (both DIY - an example I was talking in first line)? I want to make an expression pedal that would technically consist only of a pot. There would be a toggle switch between a pot in the stompbox and a pot in external expression pedal.

Picture:
http://i27.tinypic.com/2vlwl6p.jpg

I was thinking about stereo jacks, but in fact I don't know which wires to use

Thanks, JS

[RickL]

You need a maximum of a dpdt switch to switch between two pots. If all three lugs of the pot are used (e.g. a volume control) you only have to switch two of them. If only two lugs are used (e.g. most speed controls on tremolos, phasers, etc.) you only need to switch one wire so you can use a spst switch.

Example: you want to switch between an on-board volume control and an external volume pedal. Leave the ground wire connected to the original pot connected to the pot. Connect the ground wire to the sleeve of a stereo jack. Disconnect the wires from lugs 2 and 3 of the volume pot. Connect them to the two centre poles of a dpdt switch. Connect lugs 2 and 3 to the appropriate outside poles of the dpdt.

Connect the other two outside poles of the switch to the tip and ring of the jack. Connect lug 1 of your volume pedal pot to the sleeve of its stereo jack and lugs 2 and 3 to the tip and ring of the jack.

If you just want two controls in the same box leave the stereo jacks out and connect the second pot directly to the switch.

[Drake120]

Well, thanks! I'm kinda late, I know :] But I have two more questions:

1) Do I have to use stereo guitar cable, as there are two signal paths ("tip" and "ring")
2) And I just want to make sure - when I connect lug 2 to the tip in the stompbox, then I have to connect lug 2 to the tip in volume pedal? Or is it reverse?

I'm also planning to do a footswitch for my amp, I'll be using this: http://i4.tinypic.com/10qfozt.jpg

in fact I have the same question as 1) (that's why I haven't made a new topic): do I have to use stereo cable to connect it to amp?

Thanks,

(JD)^S

[Drake120]

bumpie

[F.V]

1. Yes
2. Yes, tip to lug 2
3. Yes

Rather than use a switch to switch from an internal pot to an external one, a better solution would be to use a switched input jack, meaning that when an expression pedal is plugged in then it is the pot in use, and when its not the internal pot is.
http://experimentalistsanonymous.com/board/viewtopic.php?t=148

[Drake120]

Well, I thought about the switching jack, but, when I will have the expression pedal and the stompbox on a board, it will be easier to just flip the toggle instead of unplugging the cord.

Thanks for the answers

(JD)^S