ep booster clone - noise

[emosms]

Hi again.
Don't know where to post this question.. Not IC based circuit
Built an EP booster clone (xotic). Works pretty well, but I have a background noise, when the circuit is on:
http://picosong.com/RzSw/
The recording is boosted app. 20db to make the noise more 'hearable'. It is nasty.
Actually the noise was stronger, but I accidenatly diminished it as I have put a 100uF cap in series to the ground and connected the otherway around !!!??? (plus to ground).
Connecting ithe cap reversely provides the most noise canceling for this noise ....
The cap I mention is the cap right after the diode at the power supply.
http://i21.photobucket.com/albums/b263/reverweb/EPBc.jpg

Best regards

[emosms]

There is some cap at the LED I have ommited, haven't checked that yet.
What is the function of this cap?

[duck_arse]

reversing that supply bypass cap is a very bad idea. if you are lucky, it won't explode. tiny bits of al foil and greasy paper all over the place, and your pedal won't sound any good. put a new cap in the right way round, with (-) to ground.

the cap on the led is also bypassing any noise it might generate to ground. don't reverse that one either.

post in the building your own stompbox area will get most looks.