Bipolar LED on DMI Dual Octave Pedal

[VanWhy]

Just ordered a Dual Octave PCB from Dirt Monger Instruments. It uses an DPDT to toggle 1 or 2 octaves with an individual LED for those 2 settings. (I plan on using 3PDT).

Can I just use a bicolor LED? Would that be common anode or common ground? Would it be as easy as wiring the ground of the bicolor LED to the cathode pads on the PCD and the LED anodes to the anode pads on the PCB?

 

[jwin615]

Check the schem and see which is in common. I guessing they have common power and the ground is switched

 

[falco_femoralis]

Decide whether you want the switches to be on the + side or the - side of the LED. That determines whether you use common anode or cathode

 

[VanWhy]

Check the schem and see which is in common. I guessing they have common power and the ground is switched

That's what it looks like to me...

 

[jwin615]

View attachment 105752
That's what it looks like to me...

Common anode then, to the anode of D4. Cathodes SW2 pads 1 and 3.
Jumper D5.
I think

 

[giovanni]

View attachment 105752
That's what it looks like to me...

So it’s either one or both colors on? But never the other color by itself?

 

[VanWhy]

So it’s either one or both colors on? But never the other color by itself?

I see it as just always one or the other color toggled.

 

[giovanni]

I see it as just always one or the other color toggled.

When the switch is in the lower position both LEDs are in series right? And in the other position only one of them has current. Am I looking at it wrong?

 

[VanWhy]

When the switch is in the lower position both LEDs are in series right? And in the other position only one of them has current. Am I looking at it wrong?

You are exactly right. Just verified that.

 

[falco_femoralis]

Sometimes you need to take the PCB and move things around until you get the functionality you want.

The pedal looks like it's set up with 3 LEDs - one to indicate bypass, one for 1 octave up and another for 2 octaves up. The one oct up is always on. It's weird to me they did it like that but you can clearly see +9v to ground with no interruptions. And the switch is a 3pdt footswitch as indicated by the gut shot, not an on/off/on. Idk bro

If it were me I would have a bypass LED that's white or something and then a red/blue 1 or 2 octave up LED. You can accomplish this by populating a shunt in place of the D4 LED and then place D4 in series between the footswitch lug and ground. That's for three separate LED's.

To use a bicolor I would use a common anode LED and populate the positive side in D4, and then run each cathode to either side of the footswitch, with its middle lug going to ground. If you want to get the brightness to balance (ie blue is too bright) then add another resistor between the LED's cathode and the footswitch lugs. Lately I've been using trim pots, which is great for adjusting later on

 

[VanWhy]

To use a bicolor I would use a common anode LED and populate the positive side in D4, and then run each cathode to either side of the footswitch, with its middle lug going to ground. If you want to get the brightness to balance (ie blue is too bright) then add another resistor between the LED's cathode and the footswitch lugs. Lately I've been using trim pots, which is great for adjusting later on

Good call. This sounds spot on to me. Thanks for the response. I will post back when I get it built.