Question about powering multiple circuits with a single 9v

[Cmlo]

Howdy all!

I'm getting back into this after almost 20 years and was curious if anyone could answer a question before I do all the work and learn through trial (which is likely what I will do).

I'm considering dropping my first three builds (treble boost, fuzz face, and LP Eternity) into a single enclosure. Given the low draw of these, I thought using a single 9v would be pretty reasonable.

I'd likely set up a panel to run the battery into to fork the power to the three circuits (my understanding is I'd need to drop a resistor in each line for decoupling, and then possibly a drop to ground).

My question is, given the three circuits will be hardwired together at the stomp switch, does this mean at least two of them will always be drawing power, regardless of whether the input of the first circuit is seeing an instrument cable? I know they will draw, regardless the circuit being engaged or not, when the pedal is being used (i.e. the input has a cable in it), but if they will be drawing 100% of the time I suspect I need to consider a series of kill switches for the final two circuits?

Any insight is appreciated. If no one has any, I will report back in a week or two.

Cheers and thanks!

 

[Nostradoomus]

This board is super handy, I’ve never had a problem with extra noise from 3in1 builds. Putting a 47r resistor right from the breakout to + can’t hurt though.

DC Jack Breakout Board - PedalPCB.com

Power Breakout Board

www.pedalpcb.com

 

[giovanni]

Maybe I misunderstand the question, but pedal circuits always draw power when bypassed. That avoids transients due to the circuit getting powered. So yeah, the battery will drain faster with three circuits. Combo builds are probably better powered with an external adapter.
I don’t think you need a resistor from the +9V to each circuit, but maybe I don’t know what you mean by “decoupling”?

 

[Cmlo]

Maybe I misunderstand the question, but pedal circuits always draw power when bypassed. That avoids transients due to the circuit getting powered. So yeah, the battery will drain faster with three circuits. Combo builds are probably better powered with an external adapter.
I don’t think you need a resistor from the +9V to each circuit, but maybe I don’t know what you mean by “decoupling”?

Hmmm.

Maybe my terminology is off.

If I have a battery powered effect sitting without a cable plugged into the input, it isn’t drawing current. However, if I leave a cable plugged into the input, it will draw power. It would seem inserting the jack of an instrument cable into the effect is what completes the circuit and therefore initiates the power draw.

My question is, if there are three circuits hardwired in series from input jack to the output jack, does not having an instrument cable plugged into the input mean none of the circuits are drawing power, or only the first circuit, as the following circuits are alway “plugged in” to the previous circuit/s?

 

[giovanni]

Oh I see. What you describe is a switched input jack that opens the DC battery circuit when no jack is connected. It has nothing to do with the circuit but with the way the power plug and the switched jack are wired. I think this thread may help explain what I mean. Good luck!