How to add bicolour LED to a two-speed Forum Vibe?

[Solder of Destiny]

Hello. First time posting here. I can't find info on this that I can understand. So I have built a Forum Vibe with two speed pots and a 3PDT switch to switch between the two pots. I want to add a bicolor LED that will indicate both LFO speed and change colour depending on which speed pot is "on". Can anyone help?

General context: I've built a few pedals but my electrical knowledge is limited and I can't really read schematics...

 

[falco_femoralis]

It's easy, just figure out whether you need common anode or common cathode and then wire the LED into the speed footswitch

 

[Solder of Destiny]

How do I figure out if I need common anode or common cathode? It appears I have used a common cathode LED, so presumably I need a common anode one? But also, what do I have to do to get it to flash with the LFO speed?

 

[falco_femoralis]

It's determined by where the LED gets its power and the easiest way to implement a switch

If you want it to flash with the LFO then you are probably going to want to use a common anode LED so both colors will get their signal from the LFO, then you can install the CLR's on each neg lead and wire those into the foot switches

 

[Alan W]

I haven't looked at the schematic—so I'm not sure if you need all the poles on the 3P2T switch to go from 1 pot to the other. (I'd think if the pots get a ground to one of their terminals, that wouldn't need to be switched, it could be left on . But If this is wrong, and you actually need all the poles, then you will want to get a 4P2T switch.

 

[Feral Feline]

I haven't looked at the schematic—so I'm not sure if you need all the poles on the 3P2T switch to go from 1 pot to the other. (I'd think if the pots get a ground to one of their terminals, that wouldn't need to be switched, it could be left on . But If this is wrong, and you actually need all the poles, then you will want to get a 4P2T switch.

Looking at the schematic, nothing on the pot(s) are going to ground — However! ...


The dual-ganger SPEED is wired as a rheostat (both gangs), not a voltage divider.
Need two poles for each input to GangA-3 lug & GangB3 lug, but the outputs are all going to the same stream ie lugs GangA2&1 and GangB2&1 are all tied together.



3PDT should be doable.




@Solder of Destiny ...

May or may not help to have a look at this SWITCH-CRAFT thread:

Post in thread 'SWITCH-CRAFT (got any creative uses of switches?)'

Apr 15, 2025

More switching twitching Aggregavation©™...




From this Expandora thread, some hot pot swaps:

IIRC— ROBERT's method:

DGWVI's straightforward pot-swapper:

MMMMMMm mmmmm mmmmmm HOTPOT!

• Feral Feline

• 
• 

Here too:

Post in thread 'Fender Blender - Volume bypass switch'

Feb 19, 2025

That's not going to work.

That's not how DPDT switches work.

DPDT = two poles of stacked lugs:

POLE A
1—
2—
3—

POLE B
—4
—5
—6

TOGETHER, the DPDT:
1— —4
2— —5
3— —6


Your point #4 says to connect lugs 4 and 6. Then you won't be switching anything on that pole.

Here's a bunch of DPDT switches of various types, they show how POLE A and POLE B connections go up or down together.





KISS IT BETTER
Here's a simpler idea for maxing out your VOLUME/LEVEL, and you could do it with just a SPST toggle, but if I understand correctly you want a DPDT-stomper and...

• Feral Feline

 

[Solder of Destiny]

Thanks for the responses. I was flattering myself when I said my electrical knowledge was limited. In reality, when I build a pedal I am painting by numbers.

I have no idea how to go about this.

If it helps, I've wired up the pedal like this




With serial switching between the 2 x two-gang speed pots, as below:



Which leaves one pole of the 3PDT switch free (as per diagram), at least in my understanding.