Hello,

I would like to add a dual colour led to my wah (orange/green). http://www.farnell.com/datasheets/33608.pdf
i would like the led to be orange in bypass mode and green whilst active.
Could anyone tell me how to wire this to a DPDT true bypass switch?

Regards, Eric

You'll need a 3PDT as both poles of a DPDT are used for the true bypass part. Centre pin of a bi-colour LED is common cathode so connect that to ground. Connect the supply voltage through your current-limiting resistor to the centre pin of the unused 3PDT pole. The outer pins of the LED go to the relevant outer lugs remaining on the switch.

Quote from: anchovie on November 27, 2009, 06:29:16 AM
You'll need a 3PDT..

..or enhanced millenium bypass circuit (but I'd prefer 3PDT way as well )

like this?



wire the rest like a regular DPDT?

Yep, that'll do it.

That's exactly how I do bi-color LEDs whenever I need to use one.

I do the same thing but I connect the resistor to the cathode before running it to ground.

The nice thing about connecting the resistor to the plus side is that you can use two different resistor values (connect them bewteen the switch and the + legs of the LED rather than +9v and the switch) to even out the brightness of the two colors.  Some two color LEDs are pretty well balanced, but many are not.

Quote from: oliphaunt on November 27, 2009, 08:49:02 PM
The nice thing about connecting the resistor to the plus side is that you can use two different resistor values (connect them bewteen the switch and the + legs of the LED rather than +9v and the switch) to even out the brightness of the two colors.  Some two color LEDs are pretty well balanced, but many are not.

Good point.

this is ok?
the switching part is taken from a standard 3pdt schematic, but is the bi-colour led hooked up correctly now?




kind regards, eric

everything else is fine, but now it's connected so that the LED will be green in bypass. (you might have noticed this, and just were lazy drawing the picture.. )

haha, yeah i was a little lazy.

Thanks for verifying the wiring.

this is wah't   it should be like in the end.



Regards, Eric

 You should consider rewiring signal switching (on footswitch and on EQ's DPDT as well) to not put unnecessarily two switched contancts in the way in the bypass position plus to ground input of bypassed circuit (see "True Bypass with Circuit Input Grounding" with DPDT switch at www.generalguitargadgets.com). T.