No battery drain on bypassed effects with simply a 3PDT, with a LED

[asfastasdark]

A problem for many effects is that when the effect is bypassed, the transistors, op-amps, or whatever else is pulling current is draining the battery even when you're not using the effect. People have suggested using a 9V adaptor plug to switch battery on or off by plugging it into the DC jack, but I've found something better. This makes it so that the 3PDT switch doesn't switch between LED grounded or not, but V+ reaching the LED and everything else (including the board) that requires V+.

[aron]

I think that part of the problem is that there is noise when the effect is switched on. Probably a loud pop....

[Boogdish]

What Aron said.  It might be a really acceptable/transparent pop on some effects, though.

[R.G.]

I think that part of the problem is that there is noise when the effect is switched on. Probably a loud pop....

Actually, that's all of the problem. There are only two effects I know of that don't do that.

I do know a way to fix this, but it requires adding more circuitry to the pedal, and putting up with a period of silence when you switch the pedal in. The silence is there to prevent the pop, of course. The time of silence depends on the pedal being powered up, and must in general be adjusted to match the pedal being used.

What you do is to put in an always-powered CMOS logic circuit that accepts as suggestions the state of the bypass switch and whether the pedal has a plug in its input or output jack. The circuit then decides based on these to turn the power on/off as needed, and also to mute the output for a short time to mask the pop.

There's another way as well. You could put a one-shot circuit in that's fired by the pedal power coming on and like the first one causes a short mute time. My experience with power-on one shots is that the always-on CMOS will work better. CMOS left on 100% of the time uses so little power that the battery life will not be changed at all.

The circuit is not too complicated, and you could probably toss in a Millenium C while you're at it so the thing would work from a DPDT as well.

[kurtlives]

Fuzz Faces draw what 3mA of current when bypassed? 

[R.G.]

There are many which draw very little. There are some which draw a huge amount. It kinda varies.

[frequencycentral]

What about my tubes? They take a minute or two to warm up............no wait..........you guys put opamps and transistors in pedals??? Crazy man!

[asfastasdark]

Hm. Too bad. It already seemed to good to be true. 

[R.G.]

No, don't be discouraged - it just pops loudly if you don't think of some way to fix that.