Estimating power consumption of pedals

[pdavis68]

I just put in the order for the final parts I need to complete my 9 almost finished pedals. I'm putting them all in one box and I'm now working on the power supply. The pedals I have are:

1 - Angry Red Camel
2 - Emerald Ring octave effect
3 - DSOTM Fuzz
4 - SWAH autowah
5 - Big Muff Pi
6 - Zenith Pro Overdrive
7 - D'Lay w/tap tempo daughterboard
8 - Fo SHO boost
9 - NPN Fuzz Face

There's also going to be an LED per pedal. What should I estimate?

I've got a 12VAC transformer rated for 1.5A (going to rectify and regulate it to 9VDC). My hope is that there's plenty of power left over on the transformer as I have some other pedal ideas to add in.

[chuckd666]

Glancing at that list I'm sure you'll be fine, digital effects are the only ones with quite high draw which may lead to issues (digital effects just turn off if the draw is too high from my experience).

[slashandburn]

If they can all be individually powered by a single 9V battery,1.5A should plenty be plenty.

[GibsonGM]

If they can all be individually powered by a single 9V battery,1.5A should plenty be plenty.

Yeah, you'd think!  But if you're really worried (or just really curious)...take a battery clip, interrupt the + wire, and connect ground to your pedal of interest, and connect hot to your DMM red probe.  Use the black probe to send power to the + input (the power from + flows thru the meter, in series).  Set to mA, THEN connect the battery, see how much current the pedal draws.   There are any number of ways to do this, as I'm sure most know, but this is the basic idea.

The biggest power consumer in the pedal is most always going to be the LED. So for more power savings, up the LED resistor value...

[GGBB]

As Mike said, if you're worried, measure. I'd just ballpark it - 9V / 12V * 1500mA * 50% regulator efficiency (way low) / 9 pedals = 62.5mA == plenty per pedal for analog. Probably a very inaccurate (low) guess, but makes the point.

[slashandburn]

Ah I've likely got this one wrong, my apologies.

So, say for example, each pedal drew 200mA  (purely as a figure plucked from the air) would he want 9 x 200mA plus some breathing room for adding other pedals?   So 2A or more in this arbitrary example of mine?

Would this be the way to go about adding up power requirements in this case?  Obviously substituting my figures for the current draw of the 9 peal listed in the OP.

[GGBB]

Ah I've likely got this one wrong, my apologies.

So, say for example, each pedal drew 200mA  (purely as a figure plucked from the air) would he want 9 x 200mA plus some breathing room for adding other pedals?   So 2A or more in this arbitrary example of mine?

Would this be the way to go about adding up power requirements in this case?  Obviously substituting my figures for the current draw of the 9 peal listed in the OP.

As a starting point, precisely. That would get you the minimum power supply requirements going in to the pedals. If you are planning to "process" the power coming out of the supply before going in to the pedals, you will also need to calculate the amount of loss that introduces. So - stepping 12V down to 9V or using a regulator, filtering perhaps (RC?), will consume current that can no longer go to the pedals.

[pdavis68]

Thank you all. Sounds like I'm good to go. Just waiting for those last parts to show up.

[GGBB]

The biggest power consumer in the pedal is most always going to be the LED. So for more power savings, up the LED resistor value...

+1M

I've been using 10k resistors with ultra-bright LEDs recently - gets the LED current well below 1mA with plenty of brightness. In the old days with ordinary LEDs we'd be using 10x that or more - just for the LED!

[GibsonGM]

The biggest power consumer in the pedal is most always going to be the LED. So for more power savings, up the LED resistor value...

+1M

I've been using 10k resistors with ultra-bright LEDs recently - gets the LED current well below 1mA with plenty of brightness. In the old days with ordinary LEDs we'd be using 10x that or more - just for the LED!

Ha ha, exactly! When I first went to the 'ultra modern newfangled ultra brite LEDs', I could NOT believe how high I had to make that resistor to not go blind!   I would give advice online like "Just pop a 470R or better in and you are good" - people would write back "I'm BLIND!"  lol

Hey, Slash - highly doubt ANY of those are drawing 200mA!!!  If any drew 20mA I would be shocked out of my mind...I hope pdavis will test the delay and the autowah, see what those draw?   I mean, an LED is probably 1 or 2mA if ultrabrite (10mA or so if not), and the board is probably drawing a couple more, on the ones with LFOs.     But yes, you would add them all up and put in a 'fudge factor'.

If I were doing a PS at all, I'd do the 1.5A, maybe 2A, regulated 9V, and call it good.  That will run MANY MANY pedals!   

[Beo]

just be prepared in case any of those circuits bleed LFO or other noise into the power circuit. Some pedals just don't play nice with other pedals when they share the same supply. I usually just use a dedicated wallwart for those (vibes in particular). You can try various techniques to isolate, including dedicated regulators, but not the same as truly isolated power lines. I still want to build a multi-output supply using the weber transformer... or maybe just buy a pedal power from voodoo labs.

https://www.tedweber.com/wpdlxfmr-1

http://www.voodoolab.com/pedalpower_2.htm