Rate led tremolo

[Marbles]

Hi Guys and Girls,

I have added an led to a vox repeater. This flashes in time of the rate. So far so good. I just want it to be off when the effect is off, and I just can't seem to wrap my head around this. Even after extensive searching.

The Cathode is connected to B2 of the 2n2646 and the anode of the led with a resistor to 9v.

This will mean the led is always on ofcourse. There's always 9v going to the led, but since the anode of the led is not connected to the 3dpt switch (connecting and disconnecting it from ground) switching the effect on and off won't do anything.

What would be the correct way of doing / thinking?

[Travis]

Good question.

Remember that with your 3PDT only two poles are needed for mechanical true bypass. The normal layout we use here links the “LED pole” common to ground but you don’t necessarily need to do that.

You can connect whatever you want to the common of the LED pole as long as you don’t wrongly connect it to another part of the switch/circuit

In so many words, I would connect the LED anode to 3PDT lug 1. Then the resistor from 9V to 3PDT lug 2.

Lug 3 of the 3PDT doesn’t need to be connected to anything. The main point of the “LED pole” is to switch the LED, so having no connection in the off mode is not a problem

This is assuming the 3PDT is numbered like this

147
258
369

[Marbles]

Hey Travis!

Hope you've been doing ok! Thanks for taking the time to answer.

I think I get it :D
The Cathode will be always connected to the board, and the anode will not get any 9v when the switch is in the off position. Cause in the off position numbers 2 and 3 are connected.
By turning it on, a connection is made between lug 1 and 2, giving the led power.

That's smart, thanks a lot!

[Marbles]

Hi Travis,

One more question if that's ok?

I tried it and it works, awesome! The only difference is that the 9v is going directly to lug 2, and the anode goes with a resistor to lug 1. I had it attached to the led and didnt think it would matter. Correct me if i'm wrong!

Now I have a lot of ticking in bypass. If I connect lug 3 and 6 however, it gets a lot less (barely noticable).
I understand by doing that I am connecting the 9v going to lug 2 directly to ground when the switch is off. Would this cause any problems?

[Travis]

Perhaps it would be better to keep the LED always connected and disconnect the power from the whole circuit while bypassed. Mark did this with the BYOC trem to avoid ticking in bypass

There would probably be an “artifact” while switching

I think if you short your supply it will likely enter a fault protection mode

[Marbles]

Haha, let's not do that then :D

I will use this knowledge in a future build, thanks a lot. I have de/resoldered all the grounds, separated them etc so it looks like a warzone in there. Going to settle for a constant led (removed the ticking). It's for spacemen stuff, so with the depth all open, it's hard not to miss the tempo haha.

Thanks for all your time, learned something new!