Gimme a hand here with simple overdrive!

[smoguzbenjamin]

Hey!

I was breadboarding the Easy Overdrive on the GGG site and I substitued some parts for bits I allready had lying around going to waste. Now the clipping sounds cool, almost square wave-ish (so I'll call it square-synth instead :mrgreen: ) But the attack is really loud and then the volume goes down alarmingly. On the whole the volume of the guitar signal is very low compared to clean signal. Also, when I play the strings with normal force, it pops angrily at me. I have to play teeny-weeny real quiet with this thing... Anybody have suggestions?

here's the schematic:
http://scorpius.spaceports.com/~ubermaus/guitar/od.html

[gez]

You could try wiring up a pot for variable resistance and connect it in series at the input.  This would probably tame down the attack a bit.  47k perhaps?

[Gary]

Sounds like the transistor is mis-biased.  What is the voltage on the collector?

[petemoore]

Sounds like you're experiencing gating or biasing problems, possibly due to a transistor pinout mismatch, [make sure you have emitter, base , and collector making all/only the right connections], or it could be some other problem].
  First make double certain the pinout is correct, also the wiring and resistor codes [it's a good practice to DMM verify your resistances before soldering them in].
 IF there's still problems post your transistor pin voltages: emitter, base, and collector,  from ground [voltage readings taken with a DMM].

[smoguzbenjamin]

Well, I checked the transistor, according to all the pinouts I found it was orientated correctly. However I did turn the tranny round (it has a center base) and this sounded better. The clipping was rounder, and much less of the popping attack problem. Yet the signal was still weak... Damn.

BTW the schematic says 680 Ohms on the resistor/cap to ground from the emitter. It should be 680 K.

Here's the voltage ratings:
C) 1.75 V
B) 1.25 V
E) 1.28 V

I think the 1uF cap that should be a 22 uF is my main suspect, and the 200K resistors that should be 220. I think I have a 22 uF cap on a non-working project, Maybe I'll rip that off it this evening and try that...

[jrc4558]

you may want to try at least 2N3904 or 2N5088 instead of the 2N2222.
The Hfe issues may be the cause.

[Joe Davisson]

The 680k is way too high, try to dig up a smaller one. Doesn't have to be exact, but shoot for at least 470 ohms up to about 2.2k. This is the biggest problem.

If you fix that, and raise the 1uf to something larger, and increase the 470pf cap (can be .1 instead of .01) it will work better.

[smoguzbenjamin]

I replaced the 680K with a 1K  :oops: oops. I changed the 470pF for a 0.1 uF, and it sounds even worse! I've yet to replace the 1uF with a 22uF I just found on a dead board. Then I'll see again, but no positive results yet...  :?