a little OT, but related with stompboxes

[Marcos - Munky]

I was taking a look in my schematics, and I saw that some need DC power supply. What is the difference between AC and DC power supply?

[travissk]

DC Voltage is like a battery. It supplies a (hopefully) constant voltage. At any given moment, the voltage supply will be for instance 9V.

AC Voltage is sinusoidal. It's what comes out of the wall. It's rectified and filtered to give you DC.

Most pedals need DC, and all that can take batteries can run on DC. There are some pedals that take AC, most notably some of the Digitech pedals... when the adapters break it's so hard to find a replacement that they're hoping you'll just shell out $50+ for a replacement  :evil:

[Marcos - Munky]

Thanks. I understood.

[Ge_Whiz]

I bet the first thing that the AC runs into when it goes into a Digitech pedal is a bridge rectifier, since I can't see the pedal using AC for any purpose. Thus, not only could you replace the PSU with a DC one (of correct voltage), the polarity wouldn't matter either...

[Paul Perry (Frostwave)]

I bet the first thing that the AC runs into when it goes into a Digitech pedal is a bridge rectifier, since I can't see the pedal using AC for any purpose. Thus, not only could you replace the PSU with a DC one (of correct voltage), the polarity wouldn't matter either...

Maybe, maybe not. Some of the pedals I manufacture use AC supplies (anywhere in the 14v to 18v range) whish converts to +15 and -15v regulated rails, to drive the cloned traditional analog synthesiser ciruits therein. You won't gt far with a DC pack for those..
Anyone who doesn't wnat ot pay $50 for a boss PSU, there are plenty of equivalents at www.jameco.com for a tiny fraction of that!

[travissk]

Yep, I ended up ordering at Jameco last week after your suggestion in jimbob's thread (thanks!).

I opened up this pedal (one in the XP series) when I got it and it seems to be rectified, but on the other hand I've heard that people have ebayed 'broken' Whammy pedals because the power supply broke and the radio shack guys said "9V? Yeah, we've got one of those" and handed them a 9VDC supply. I can open up the whammy when it arrives, but it's possible it can use DC as well; I know it uses a lot of current (750mA+ 9VAC) so perhaps the radio shack adapter only pulled something like 200mA.