Author Topic: Germanium PNP Fuzz Face breadboard, getting loud scratches  (Read 368 times)

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Jamdog

Germanium PNP Fuzz Face breadboard, getting loud scratches
« on: April 23, 2016, 11:26:33 AM »
Hello.  I am attempting to build a fuzz face from schematics found online :



The transistor are what I believe to be germanium PNP that I pulled from vintage avionics equipment,  they have a rather low junction voltage (180-190mili)
The 2.2uF is two 1uF in parallel.
The 0.01uF is a 100nF
The 20uF is a 22uF
All the rest is as per schematics.

I can't get the fuzz knob anything high,  or all I get is scratchy noise.
The volume knob is cranked up and I get a lower than I anticipated volume.
  I am thinking values aren't well suited for the transistors?

Here's the breadboard
http://imgur.com/ab7Hhnf

Here's a tentative on how it sounds,  but recording doesn't show how loud and harsh the clipping sound ends up being...

https://clyp.it/1t5ildsc

What should I be looking into?  I am thinking the specific transistors needs different bias than what we get,  but am not experienced in germanium whatsoever. 
-Jamdog

Ben Lyman

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #1 on: April 23, 2016, 12:22:03 PM »
Make sure that's a 470r on there, looks like maybe a 470k in your pic.
cheers
"Hey Yorgi, Oozviks drank all my oil!"

R.G.

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #2 on: April 23, 2016, 12:22:55 PM »
It could be oscillating. It would be good for you to put a 10uF-22uF electro cap paralleled by a 0.01 to 0.1uF ceramic cap from the power supply (junction of the 33K and 470R resistors) to signal ground (ground side of the fizz pot). This will probably help with oscillation problems, and will not hurt in any case.

There may also be problems in wire routing.

Schematics don't show it all. That's why they're schematics, not finished units.
R.G.

Quick IQ Test: If anyone in a governmental position suspected that YOU had top-secret information on YOUR computer, how many minutes would you remain outside a jail cell?

Jamdog

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #3 on: April 23, 2016, 12:28:32 PM »
Make sure that's a 470r on there, looks like maybe a 470k in your pic.
cheers
Good eyes Ben!  Meter says 0.468M

Well,  looks like I don't have any 470 ohms like I tought I did,  wrong scale.  Lol.  Let me dig out something...  I have a 330 somewhere,  or can parallel two 1k. Let me check and I'll be back!
-Jamdog

Jamdog

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #4 on: April 23, 2016, 12:39:09 PM »
Make sure that's a 470r on there, looks like maybe a 470k in your pic.
cheers
Good eyes Ben!  Meter says 0.468M

Well,  looks like I don't have any 470 ohms like I tought I did,  wrong scale.  Lol.  Let me dig out something...  I have a 330 somewhere,  or can parallel two 1k. Let me check and I'll be back!
Found a 470

World of difference!
Ben you're a genius,  found it in no time!

I only had time to make supper!

It sounds good,  I am having fun with it!

Really sounds fuzzy. 
Here's how it sounds!

https://clyp.it/kxfg5chz


Now I need to get a 3pdt switch,  and an enclosure.  Lol.

This is really fun to play with.

Thanks a lot Ben!

« Last Edit: April 23, 2016, 12:43:44 PM by Jamdog »
-Jamdog

Ben Lyman

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #5 on: April 23, 2016, 12:46:21 PM »
Sounds much better  8)
have fun!
"Hey Yorgi, Oozviks drank all my oil!"

Jamdog

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #6 on: April 23, 2016, 03:01:48 PM »
Sounds much better  8)
have fun!
Go figure.  Put all the parts on perfboard,  no-go.  What did I miss?  Lol.  At least I know the circuit is good,  all I have is to debug it :)
-Jamdog

Ben Lyman

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #7 on: April 23, 2016, 03:37:44 PM »
Sounds much better  8)
have fun!
Go figure.  Put all the parts on perfboard,  no-go.  What did I miss?  Lol.  At least I know the circuit is good,  all I have is to debug it :)
Bummer  :(
Only thing I would always check first (because I've messed it up so many times before) is to make sure the plain ol' jumper wire is in there connecting Q1c to Q2b
For some reason, as I check all my components over and over, I used to always forget to check the direct connections  :P
"Hey Yorgi, Oozviks drank all my oil!"

Jamdog

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #8 on: April 23, 2016, 03:43:08 PM »
I did not forget that one,  but the Q1 to ground....  also spotted a bad solder connection between the input and Q1. 

Thanks for the hand!

I am now looking at adding an on/off DPDT switch in lieu of the stomp.

Id like to have somewhere local to get them stomp switches,  and good enclosures. 

But it's coming along good,  I'll be able to bypass it today and compare it to my hard diode clipping pedal. 👍👍👍


-Jamdog

Ben Lyman

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #9 on: April 23, 2016, 03:50:24 PM »
I did not forget that one,  but the Q1 to ground....
Ah yes, the ol' Q1e to ground, another of those straight wired connections, good job!  8)
"Hey Yorgi, Oozviks drank all my oil!"

Jamdog

Re: Germanium PNP Fuzz Face breadboard, getting loud scratches
« Reply #10 on: April 26, 2016, 03:39:15 AM »
I don't have a stomp switch yet,  but in the meantime....