Adding a second volume and gain control with 3pdt and LED

[schtaf]

Hi Everyone,

I am currently doing a rehouse of a handwired menatone bluecollar, and while I am at it, I thought I'd add another stompswitch to be able switch between two volume/gain settings that i frequently use for rhythm/lead. The pedal itself has the basic tubescreamer circuit, with standard gain and volume knobs. I believe the pedal has rat style or an early millenium bypass system.

What I would like is for the switch to switch between Gain/Vol set 1 and gain volume set 2, and have an LED come one with one of the sets. It should be fairly simple but haven't been able to figure out yet. Only been able to draw up a way with a 4pdt, which I would like to avoid.

Any help would be much appreciated!

Schtaf

[deadastronaut]

use the search....im sure ive seen  a diagram on here somewhere..

a lot of people do it to there dr boogeys now....maybe look at that mod...

using 2 ,3dpt's....

[schtaf]

Thanks for that. So far I've figured out how to wire up either 2 volume pots and LED (3 poles required) OR 2 gain pots required (2 poles), but I'm not familiar enough with the millenium bypass/other systems to figure this out. Searching continues to take me nowhere.

[frequencycentral]

Like this?

http://www.diystompboxes.com/smfforum/index.php?topic=83901.0

[schtaf]

Thats the general idea, however I'm looking to have both switchable gain pots and volume pots on 1 switch, which is straightforward with a 3pdt, but not so (if not impossible) if I want an LED indicator to light with one of the pairs.

As far as I can tell, I would need to apply some version of the millenium to get this going, but I'm not sure if thats even possible.

Thanks

[frequencycentral]

I love a challenge:



Each pair of pots are in parallel, therefore the resistance is halved, so you may want to double the stock pot values. Really, it's only the resistance at lug 2 of each pot that we are concerned with, as the resistance between the signal and ground remains constant regardless of how the pots are set. So we are just switching from one set of wipers to another set of wipers.

[schtaf]

Hey Rick thanks a lot for the diagram, looks like it should work.

You mentioned that I should double the pot values because there were always be the parallel resistances between each of the outer lugs hanging on the output. To keep the same taper/pot value, would it be better to just add series resistors between ground and lug 1 on that diagram, or would that change things negatively?

Also, is there any mathematical principles for selecting value of the volume pot, I see anything from 250-1M and I'd like to do some reading on designing this stuff (its time i learn how to do this stuff myself!)

Thanks again,

Schtaf