True bypass a BOSS pedal (w/pix 56k warning)

[pswoods]

How the hell did you mount the switch?

Sorry - didn't mean to hijack the thread; I was just trying to show the end of the spectrum opposite genius...

I drilled out the indentation that lines up the spring and dremeled out the inside buttresses so the switch stood up high enough. Had to replace a couple caps so they could lie down flat on the PCB and clear the switch. Put the hinged lid back on and drilled it, too, to give it that not-thought-out-very-well look everyone likes. Next I'm gonna put some gold rims on it.

Then I'm gonna try this relay trick.

[Transmogrifox]

This can be reduced to two transistors and a 4.7uF capacitor.  Buffer one of the sides of the flip-flop with a complementary transistor pair (npn and pnp) with the emitters tied together like a class B amplifier.  Connect this to one side of a relay coil.  Connect a 4.7 uF cap between the other side of the coil and ground.  This configuration can be found with my spst switch driven relay driver circuit.  All you're doing is using the complementary pair transistors as an on/off signal buffer from the flip-flop.

The two transistors can be glued to the ends of the relay, and the cap can be glued to the top or one of the sides depending on how it can be best arranged inside the BOSS pedal.  Wire it up and heat shrink it like Roberto, and you have something in a smaller footprint.

The classic trade-off to this topology is that the LED is not always in synchronization with the relay state at power up.  You have to tap the pedal once to get the LED to match the relay position right after you turn on the power --- not a big deal for me, but I can imagine somebody finding it a bit of a pain to tap the switches on 10 pedals in their pedalboard right after they power it on.

The alternative is Roberto's circuit, which is more parts, but does seem to fit in the space constrained box.

[Paul Marossy]

Very clever idea!