power filtering for a wah pedal?

[fuzz_fanatic]

i just moded an old dunlop pedal i have... true bypass, vocal and sweep mods! i want to add a power supply because i don't like to use batteries all the time and i understood you have to filter the power supply if it is not regulated... well i have one of those... can anyone tell me how to filter the power? i hope a small board will fit in there...

thanks

[niftydog]

i understood you have to filter the power supply if it is not regulated

this is a common misconception, but it's not entirely wrong;

first up, an unregulated power supply CAN STILL be very well filtered.

Also, a regulated power supply can be POORLY filtered.

Regulation and filtering are not in cahoots! You can have either one without the other. Generally, cheap wall warts are the culprits. Solution; buy a name brand, high quality wall wart and be done with it!

But, if you have a CHEAP unregulated supply, chances are that it is poorly filtered. Sometimes, extra capacitors in parallel is all that is needed. Something like a 2200µF cap across the power supply might do the trick. Other options include a small resistor in series with a cap in parallel, essentially creating a low pass filter that shunts the mains power ripple to ground. A quick search on "power supply filter" will turn up more info than you really need!