Mulitcolor LED switch wiring

[NightOwl]

Hi all,

I've just decided to try my hand at pedal building and have ordered all of my relevant parts. (hopefully they are all correct!)  While I'm waiting for all the parts to come in, I'm trying to prepare myself for the build by reading everything I can find.  In the process I've also had a couple of conceptual ideas about the two pedals I'll be trying to build first, and I'm trying to sort out the wiring before the parts arrive.  All that is to say, I'm a noob but hopefully I'm learning!

To get to the problem:  I want to use a light plate on the bottom rim for one of the builds. (a Runt, but in a 1590B enclosure)  I'd like to set it up so that when the effect is off the rim glows one red, and when the effect is turned on it glows green.

I bought a tri-color LED from Small Bear and I have a guess as to how the wiring might work.  It's attached, but it's just a tiny modification of the standard Mad Bean switch wiring.  I've also removed the battery leads for my own clarity of thought, as I don't like using batteries in my pedals anyhow.  Assuming the wiring would work and I didn't destroy a critical link, that poses another question for me.

Why are the 3 bottom left lugs in the Mad Bean standard switch wiring all connected to each other and grounded?  I assume that there is a good reason for it, but I just don't know what that purpose is.  Am I wrong in thinking that the bottom left lug could be left unattached and the standard wiring would still work fine?

I'm aware this could be a really silly question to be asking, but it's been bothering me a bit because I can't figure it out.

The TLDR version:  I want to hook up a multicolor LED to be one color FX off, different color FX on.  Will this wiring work?

[LaceSensor]

Hi

Ive done this recently, and at least with the LEDs I bought it worked as shown in my cartoon attached.
The LEDs I  have were with 3 legs off the bottom. The longer middle one connects to ground (common cathode, I guess then?!).

It makes sense, and you can check it by trying each side of the led with a 9v battery and a CLR.

[Thomas_H]

Hi,
I had a look into the bicolor topic for some of my pedals and can answer this.
The schematic you have drawn will work IF the middle pin of the LED is a common cathode.
I have found bicolor LED`s that do have a common anode.

Either way you just need to try it out. If it doesnt work you need to connect +9V to the 3PDT switch and GND to the LED via the resistor.

[NightOwl]

Great! Looking at the specs for the LED I bought they share a common cathode.  Just what I needed to know, thanks!

Now does anybody know why on the standard wiring pdf the bottom left corner lug isn't just left open?  With my very limited knowledge, isn't it unnecessary?  With all the effort on star grounding, doesn't it make a tiny little ground loop with the lug above it when in bypass?  (probably so small it's irrelevant, but I'm curious...) Or am I way off base here?

[lincolnic]

Now does anybody know why on the standard wiring pdf the bottom left corner lug isn't just left open?  With my very limited knowledge, isn't it unnecessary?  With all the effort on star grounding, doesn't it make a tiny little ground loop with the lug above it when in bypass?  (probably so small it's irrelevant, but I'm curious...) Or am I way off base here?

I believe the official explanation was that it's a redundancy designed to keep the pedal grounded in case the switch fails, but I defer to someone more knowledgable to answer your ground loop question.