Turning off LED for secondary feature when pedal is bypassed?

[PedalBuilder]

I've been playing around with a circuit (Spaceman Sputnik) that has two footswitches: one for engaging/bypassing the effect and the second for engaging a feedback loop feature. I would like to have the LED for the feedback loop turn off when the effect is bypassed and the feedback loop is still engaged. I think I've found a solution, but I'd appreciate any feedback/confirmation that you all might have.
Here's the schematic:

The basic idea is that the LED pole of the bypass/engage footswitch is setup so that when the effect is bypassed, the LED pole is connected to ground. Conversely, when the feedback loop (it's labeled boost in the schematic above, but what's in a name?) is engaged, the LED pole open and not connected to anything.

When the effect is engaged, there is a positive voltage at the gate of Q1 that turns it on and connects the bypass indicator LED's cathode to ground, thereby turning on the LED. The same voltage that turns on Q1 is also applied to the gate of Q2, turning it on and connecting the anode of the feedback loop indicator to its current limiting resistor. Switching on/off the feedback loop footswitch connects/disconnects the cathode of the feedback loop indicator LED to ground, turning it on/off.

When the effect is bypassed, the gates of Q1 and Q2 are connected to ground, turning them both off and turning off both LEDs (disconnecting D1 from ground and disconnecting D2 from its current source). Power is then connected to ground through the 10M resistor, which should result in a negligible current consumption of 900 nA when the effect is bypassed.

I don't have any MOSFETs on hand to test this on a breadboard, but it worked fine in CircuitLab, so hopefully that means that it will work in the real world, too. That said, I'd appreciate any feedback that you all might have!

 

[damianvila]

Mmm.. let's see.

In regular pedals, the led circuit is not part of the effect's circuit. It's just an independent circuit, activated by one of the poles in the 3PDT. But you're constantly sending 9V to the circuit, and that's why anything you put inside the effect's circuit will always be powered. But if you put the boost led connected to the main led circuit, it will cease to have power as soon as you put the pedal in bypass mode. Just use a DPDT to control the boost, and use one pole to activate the boost in the effect, and the second pole to activate the led, but receiving the power from the led circuit. When you put the pedal in bypass, the power (or rather, the path to ground) will be cut off, and the led will turn off, irregardless of the state of the DPDT.

You'll need an extra connection for the led in the board, but that is the same as what boards with the led included in them have. Cheers!

 

[damianvila]

This is what I mean:

 

[PedalBuilder]

Thank, @damianvila. I think we’re talking at cross purposes here. I understand how to wire foot switches to turn on LEDs, which you illustrated quite nicely. My question related to the LED switching circuit that I posted above. Any feedback on that would be appreciated!

 

[Bricksnbeatles]

If I get what you're trying to do, the easiest way would be to simply have the second footswitch led connect to the main LED instead of ground. that will make it so the second footswitch LED will only be connected to ground, completing it's circuit, when the main LED is connected to ground via the main bypass switch being engaged.


this will give the status of:

• both footswitches off: both LEDs off
• bypass footswitch engaged, loop/boost off: bypass LED lit, loop LED off
• both footswitches engaged: both LEDs lit
• bypass footswitch off, loop/boost engaged: both LEDs off

 

[damianvila]

Thank, @damianvila. I think we’re talking at cross purposes here. I understand how to wire foot switches to turn on LEDs, which you illustrated quite nicely. My question related to the LED switching circuit that I posted above. Any feedback on that would be appreciated!

Yes, sorry for that. I tend to always look for the simplest solution, and thought you maybe wanted that, but clearly you just need to see if your solution works. My bad. Sorry again. Cheers.

 

[PedalBuilder]

Yes, sorry for that. I tend to always look for the simplest solution, and thought you maybe wanted that, but clearly you just need to see if your solution works. My bad. Sorry again. Cheers.

Yeah, I should have mentioned but the Sputnik circuit uses the millennium bypass to turn off a JFET that drives the feedback loop, so I need to keep the MOSFET switching solution. Otherwise, I 100% agree that your solution would be a much simpler and easier way to solve the LED problem.