1st pedal build=horrible shrieking noise

[raycroft]

Hi, all! I just completed my first pedal this past weekend , The Rocket from a schematic off Aaron's website http://www.diystompboxes.com/pedals/rocket.JPG

I used the off-board wiring off General Guitar Gadgets site http://www.generalguitargadgets.com/.../rocket_lo.gif

I changed nothing from the schematic , I did build my first pcb (yay! fun!!!). I love the distortion, it rocks! However.... this thing makes so much noise when not picked, it's horrible. Once I actually play some notes, it sounds good. It shrieks so loud, not like good feedback , either, just like hissing , shrieking , loud, crap. I obviously have something screwy. I have read about a "ground loop", but I don't know what that means . My pedal even makes noise when bypassed: it sounds like a hive of angry mosquitos!!!!! (do they "hive" ? Maybe another forum post....)

I have tried 2 different guitars through it, and different cables; same deal. I'm playing into a Line 6 Flextone, btw. Any help would be GREATLY appreciated.

[R.G.]

go the the diystompboxes forum, read "Debugging: What to do when it doesn't work", and follow the instructions, posting them there, not here.

[raycroft]

Thanks, will do. I have read his de-bugging, and yours, several times. I wished to post to DIY, however.... I sent my request 2 weeks ago (approx) and still haven't gotten approved. I sent to join@diystomboxes. no "p". I'm stupid. Soo.. no that I got that straightened out, I am waiting again and I'll post over there.
Anyway, thanks. I went and checked my inbox because of you. Your site rocks. Holla.

[Enzo]

Turn the volume control on the guitar to zero. Does the noise stop? If so, you are probably hearing feedback. The circuit has so much gain, the guitar pickups are feeding back even at low levels.

Another test for the same thing is to turn sideways to the amp when it happens. If the guitar facing sideways shrieks less than facimg the amp, it again points to feedback.

[Steve Conner]

If it buzzes and whines even when bypassed, that means it's oscillating, because you made a mistake when building it. Maybe you put a wrong component value somewhere, or got the off-board wiring wrong. Or maybe the gain is just damn high, did you try turning it down?

How do I know this, well I have a distortion pedal that I deliberately hacked to make it oscillate, and it whines in bypass mode too.

[d95err]

Oscillation seems the likely problem. Make sure you keep all wires as short as possible. Use shielded wire from the input to the bypass switch and from the bypass switch to the circuit input.

If you're using an AC adapter, you may want to add some filtering to the powersupply. E.g a 100u capacitor between 9V and ground.

[raycroft]

Great replies, all! This is my very first hand-made pcb; I didn't see why it needed to be mirror-imaged, so I made it the backwards way, then realized why it should be mirror-imaged, and in the confusion I put the 5088's in backwards! I'm amazed the thing is working at all.
d95er, when you say "shielded wire" you mean just the stranded w/ rubber sleeve outside, correct? I've seen some DPDT's (namely, my Dallas Arbiter Fuzz Face) that had just bare wire jumping the switch; so that's what I did. And I didn't use the power supply.

I finally got my admin approval for Diystompboxes, and I will post there R.G, w/ any more problems, and back here with results.

thanks for the help, all.