dummy question: wondering about current draw

[plexi12000]

does a pedal circuit drain a battery faster, or use more cuurent.....as you turn up the volume/output? or is that a "constant" thing?

thanks-

[Groovenut]

generally it's a constanct thing, but depending on the circuit you could get more current draw as the output goes up. Did you have a certain circuit in mind?

[Fast Pistoleros]

should be a kirchoffs current law problem, all current entering should be leaving so it should be constant even if its a combination circuit ?  you should be able to test probe the current and use ohms law to find current on parts of the circuit ?

[plexi12000]

thanks guys- no, i dint really have any particular circuit in mind....just say a typical "distortion" pedal or whatever.

i was just wondering....i think of stuff like that sometimes! lol   - i'm like forrest gump when it comes to 'electronics'. it just has a way of confusing the hell out of me.

some people just "get it".  i get lost- lol.    thank you again-

[R.G.]

should be a kirchoffs current law problem, all current entering should be leaving so it should be constant even if its a combination circuit ? 

No. Current leaves through the "sewer ground" return to the battery and through the output.

The real answer is that it depends on the loading and whether the circuit can drive significant current into the load connected to the output jack. A load that can eat significantly more current with bigger signals can run up power use. Whether this is too trivial to consider or CRITICAL depends on the circuit. LM386 circuits, being able to drive speakers may put out significantly more current with big signals - if a current hungry load is attached, which you don't know until someone plugs something in.

Then there's the current in diode-pair-to ground clippers. The harder you drive them, the more current they shunt into ground.

So - it depends.

you should be able to test probe the current and use ohms law to find current on parts of the circuit ?

]
Yes.

[PRR]

"It depends".

There's two classes of circuits. Small signals and large signals.

"Small" and "large" are very arbitrary, or context sensitive.

You can slam a guitar amp input with 0.000,010 Watts of signal power.

The smallest parts you can buy are 0.050 Watt handling. And parts generally work better at not-teeny DC power levels. Maybe 0.005W of steady power to be ready to handle 0 to 0.000,010W signal output.

So "most pedal circuits" eat more power just to stay awake than all the signal power they put out.

When you get to HIGH power outputs, like loudspeakers, things are different. The LM386 can put-out 0.5 Watts. But it was aimed for 9V battery radios which were rarely played at the 0.5W level. If they did, the battery drained too fast. The '386 was designed to idle at 0.050 Watt steady power demand, then increase as you forced loudspeaker level higher. If you kept it down, battery life was acceptable; OTOH you could play a song or two fairly loud.

If you actually meter some pedals in action, you will find exceptions. Some clippers have very small resistors feeding their diodes. Chip opamps are typically "power" amps, able to increase total current as needed. The internal diodes are getting more current than your instrument amp input would ever need, and maybe more than the chip's idle current. OTOH limiters often increase (OR decrease) current in an amplifying stage to change the gain, so will vary some with signal. (I was looking at a studio limiter which falls-off from 200mA small-signal to 10mA large-signal.)

Remember that in many pedals the LED is the biggest current, and is typically constant.