What switch do i need?

[patrick398]

I have a circuit where an LFO is either controlling phase shifting or tremolo. I'm using a SPDT on (off) on so top goes to phaser, bottom to tremolo and centre disconnects the LFO from both. This LFO seems to be bleeding through somehow though, i can still hear it wobbling the phase shift when it's in the off position. So i was thinking of using a different switch and grounding the LFO when it's in the centre but i can't seem to think of a way of doing this. I feel like what i need is a SP3T but they're crazy expensive. Is there a way of doing this with just two poles?

[duck_arse]

supply bypass. show us your circuit, I bet the two sections aren't isolated.

[patrick398]

Crikey, it's messy and a bit of a moster, here is the relevant section:

[duck_arse]

moster or monster, two different things.

also, crikey. are you modulating VR and VB?

[patrick398]

moster or monster, two different things.

also, crikey. are you modulating VR and VB?

Monster! It's based on the maestro phase, so OTA phaser and the transistor/fet section was taken directly from the madbean stage fright. It all works very nicely, just having issue with bleed through. When you say supply bypass do you mean isolating the supplies of the LFOs from each other? The usual small resistor, cap to ground trick?
Both LFOs are getting 5v from a regulator

Thanks Duck

[duck_arse]

I did mean isolating, but now I see the monster I'm not so sure. if the open 220k on position 3 of that switch [it's all a little diff to read this end] is the bleeding, taking that free end to ground or maybe Vb should stop leaks. if pos 1 leaks, pull it to ground. I thimk.

[patrick398]

Yeah I thought of grounding that LFO (there are two) but that's takes me back to how...I need another pole unless there's some trickery I'm not aware of

[antonis]

Rotary switch, perhaps..??

[patrick398]

I think the issue must have been elsewhere in the PCB, cutting some traces and hardwiring those connections seems to have cured the bleed. Now to find out where the issue was....FUN! On the plus side I can still use a spdt