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Help! W/fuzz face

Started by Harris, December 23, 2005, 02:13:16 PM

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Harris

I'm attempting to build a fuzz face and all I get out of it is "Blaat... blaat... blatttt"  Base on what I've read, my bias is wrong.  Ordered my transsitors from small bear, I came very close to the suggested resistor values to the that were sent along with my transistor set.  I've built the PNP negative ground version on generalguitargadgets.com  My voltages are:

Q1 
E 8.7
B 8.69
C 7.62

Q2
E 7.79
B 7.62
C 7.76

Does anyone have any suggestions.  I've looked and tweaked at this thing until I'm blue.

petemoore

  Both emitters are rather high.
  Q1 isn't, but should be connected to Gnd.
Convention creates following, following creates convention.

Harris

Check it out:
http://www.generalguitargadgets.com/diagrams/fuzzface_sc_pn.gif

Q1 is connected to the + of the battery instead of ground.  I'm clueless as to what is wrong.

Joecool85

#3
I would use a different schematic...that one seems strange to me, here is the one I used, it works great:

http://www.montagar.com/~patj/fuzzface.gif

**edit**
I think that what you problem is, is that normally PNP fuzzfaces are positive ground, and NPN fuzz is negative ground.  Someone correct me if I'm wrong.  Regardless, the schematic I posted is a proven one.
Life is what you make it.
https://www.ssguitar.com

petemoore

  I caught myself this time. Hope I didn't do any damage.
  I've built the PNP negative ground version, that probably isn't the best FF schematic for FF beginners, I don't understand it, but I guess it somehow works sometimes...
  Joe Cool has provided a schematic that if wired correctly, I know will work.
  I've got to remember to read more carefully.
Convention creates following, following creates convention.

Harris

Petemoore...no harm done.  Although, I would REALLY prefer to get this pedal up and running as built instead of taking it all apart and basically starting over. If I can avoiud taking the circuit out of the box, I'd like to go that way.

petemoore

  Well if you get help for that problem, a circuit I just avoid...might require taking the board out anyway...I don't know how to fix it.
  That circuit is known for wierdness, I don't recommend it unless you know more than I do about it.
  I'd build a PNP POs Gnd FF, just to have a 'FF" circuit to compare the PNP Neg Gnd ff Circuit to...in your case, I'd wait for help more, or just convert like many before you have, to a pos Gnd. [please post schematic to work off for help here, we've got a batch of FF problems threads today, many don't even have a schematic to work from, give partial voltage readings etc., very hard, long, reads to find just what the heck ones 'has' in the first place, typing in 'Read and Respond to: what to do when it doesn't work' ...doesn't help...then I decide to I give up!]
  I'd leave that PNP Neg Gnd thing alone until you have a FF that works, wrench the board out and start converting or just wait until you know how to do the Neg Gnd thing on it...mostly I read it causes transistors to sound wierd.
Convention creates following, following creates convention.

Joecool85

There really isn't much to do to convert it to positive ground...basically turn your caps and battery.
Life is what you make it.
https://www.ssguitar.com

petemoore

  First order of business should always be...choose a known working schematic that is 'correct for the transistors.
  Use the old schemaitc to compare and contrast to, it should be fairly easy to find places to make the necessary re-routeing to the new schematic.
Convention creates following, following creates convention.

Joecool85

Quote from: petemoore on December 24, 2005, 11:51:28 AM
  First order of business should always be...choose a known working schematic that is 'correct for the transistors.
  Use the old schemaitc to compare and contrast to, it should be fairly easy to find places to make the necessary re-routeing to the new schematic.

This is key.  As far as I know, the trannies you have work better(or maybe at all) with a positive ground pedal.
Life is what you make it.
https://www.ssguitar.com