freestompboxes.org

hi

I am trying to make this one work.... I have no signal at all.

I tried to follow the signal with audio probe.
I have signal at the b leg if the 1st transistor, but nothing on the C.
As I;m not quite sure how to determine if a transistor works OK I tried changing the one there but still no signal comes out.
other than faulty transistor what else could cause this?

also what voltage should I read on the transistors pins?

this is what I am getting on the transistors

E - 1.74 /2.15
B - 2.13/2.68
C - 2.83/2.15

The Emitter of Q1 (the lower one) should be grounded, so should be at 0 volts - Check your ground wire is connected correctly.

thanks. it works now
I get nice fuzz but low volume - with vol and fuzz on max it is below unity

Check all your connections and cuts again carefully, there mmay be another error. Particularly check the cut between Q2 and the 100n cap leading to volume 3. When your confident it's all as it should be , measure voltages again. It's pretty much a fuzzface, so a google search for "fuzzface voltages" will give you ballpark figures.

E - 0 /5.36
B - 0.61/1.34
C - 1.35/0.73

I think they are ok... bit higher than what I found to be ideal. ?

I will follow the exit cap path

I think you've listed collector and emitter reversed for Q2 when you've measured them: Q2 collector is usually said to be ideally around 4.5v, 5+ is ok: Emitter is usually around a volt or so - This is what makes me think you've listed them wrong. It's possible you have soldered them in the wrong way around - Check your pin-outs carefully against the layout.

yes - apologize

E - 0 /0.73
B - 0.61/1.34
C - 1.35/5.36

this is what it sounds with bc109b
http://snd.sc/1aDP8MO

and with bc169c
http://snd.sc/1diK2qh

Ok, those voltages make more sense now. I can't listen to the soundclips on my phone, but I'll have a listen later. It should sound like a silicon fuzzface, but the volume drop is puzzling: The output cap+volume pot combination (100n x 22k) is not far off the standard fuzzface (10n x 500k), so the low end response will be similar to a fulltone (?) which I believe uses a 10n x 250k to reduce the low end and make it seem a bit brighter, or less mushy. It should still have plenty of volume on tap, certainly well above unity when cranked.

it does sound like silicon ff,
the pots were puzzling for me, but I kinda followed as close as I could.
I wired parallel 330ohm resistor to B1k pot and got it around the wanted.
I had a B22k pot for the volume.

aside from the volume drop one more thing makes me scratch my head. this is by far the most silent thing I ever tried. I am testing it without a box - wires on the desk and crock clips. the thing generates almost 0 noise. less than a fuzz face in a box I should say. maybe that's result from the cap+volume pot combination

ok.
I have build this 2nd time from scratch... and I have the same problem with the volume.