Rat tone control problem

[rubberlips]

G'day guys,

Just checking the tone control section on a Rat pedal I made, however the change seems to be very slight. It's got the 100K pot in series after the clipping diodes, with a 1K5 resistor and a .0033uf cap to ground. However it doesn't seem to change the tone at all when I'm looking at the signal after the 1.5K resistor with a cro, only the level changes slightly.

Is it suppose to do this?? Or is that cap value wrong on the schematic?
I noticed in some of Jack Ormans designs he uses 0.01uF caps with a 100K pot and 1K resistor in series. I added a 100n cap in parallel with the .0033uf cap which changed the signal a lot more.

Has anyone else noticed this before when they made rat pedals??

Cheers

Pete

[strungout]

Hmm, the values seem right. Maybe there's not alot of treble going into the circuit to begin with, so turning the knob wouldn't seem to cut as much. I'd also check the pot with a DMM just to be sure.

What schematic did you use?

[NaBo]

huh... thats weird.  my rat's tone pot has a HUGE effect, in overall volume as well (no adjusting on-the-fly for this baby).  i built GGG's.

[RLBJR65]

Must be something not quite right. I just boxed one up last week w/100k tone pot no mods. or changes except for the fets because I didn't have the right ones. Mine works just like NaBo said lots of tone and some volume drop at lower tone settings.

[rubberlips]

yeah, the pots okay 100K. It's a log pot.
The schematic I used was http://www.diystompboxes.com/pedals/PCRAT1.GIF
double checked and checked again, all the points around the tone control are there, there's nothing else connected. As I said, with 100n cap in there, there's plenty of tone control.
There should be enough bass frequencies going into it, the guitars got a humbucker on it, but I do use the treble pickup and tone and volume all the way up.

Hmmm, one of those weird ones I guess.

Cheers

Pete[/code]

[rubberlips]

Guy's I found the problem, although it wasn't extremely evident as everything seemed to be working correctly, unit a wire fell of the tone control and I was trying it with my guitar! It was still working as it was before, and as you can see from the schematic - pot comes out no signal should be present at the output.

So I traced, and measured and traced  and measured again, nothing's joining from what I could see - scratched head :?, traced signal on the output FET, then  rechecked the vero board. There was a mickey hair of copper that I didn't drill properly that connected the negative of the 4.7uf cap directly to the gate of the output FET (smacked self in head) :wink:

Fixed it up and it's a ripper, I'm sure I'll have fun with this baby

Cheers

Pete

[MartyMart]

HA!!
Just had the exact same deal with my "May Queen",  a microscopic solder bridge, thinner than a hair ! ( vero-board ) I was going nuts for hrs trying to figure what was wrong ....... DUH !
Well done  

Marty.