gated Fuzz face prob

[philbinator1]

Hi guys,

I'm making another Fuzz Face for a friend, which i thought would be pretty simple.  But, after populating the vero
I put it on my breadboard to test and i'm getting a really stong gated sound...only sounds if I hit the strings hard.  Really nasty. 
Here are the trannie voltages:

Q1   E: Zero volts
       B: 0.653V
       C: 1.324V

Q2   E: 0.8V
       B: 1.328V
       C: 8.48V

Battery: 8.5V

There are no mods, with the exception of a 10K trimpot where R3 was, so I can bias.  When I adjust the trimmer the voltage
only goes down from 8.48V to 8.44V or something like that.  Am i right in saying the collector of Q2 is way too high?  should it be around 4.5?   
I have double checked my vero layout and it appears as it should be, no solder bridges either.  Maybe I should re-solder?

oh and i'm using a 100K-B for the volume and 1MB for the fuzz pots.


Cheers,
Phil   

[rousejeremy]

I'm willing to bet your fuzz pot is the problem. 1 Meg is HUGE! I made a fuzz on the breadboard that was sweet sounding with a 1K fuzz pot, and gated with a 2K. Amazing how much of a difference a little change can make. 
Use this link http://www.diystompboxes.com/analogalchemy/emh/emh.html when building fuzz faces, it'll save a lot of stress.

[philbinator1]

I'm willing to bet your fuzz pot is the problem. 1 Meg is HUGE! I made a fuzz on the breadboard that was sweet sounding with a 1K fuzz pot, and gated with a 2K. Amazing how much of a difference a little change can make. 
Use this link http://www.diystompboxes.com/analogalchemy/emh/emh.html when building fuzz faces, it'll save a lot of stress.

  D'oh!  I used 1M instead of 1K!  Haha!  Thanks man I'll do a switcharooney and see if it works.   

[philbinator1]

I tried it and to some degree it worked, but i'm still getting a high reading (around 7.5V) on the collector of Q2.   

[rousejeremy]

What trannies and what layout are you using?

[philbinator1]

heres the layout:    http://i809.photobucket.com/albums/zz13/philbinator1/Fuzzfacesilicon.gif

i'm using 2N3904's, just like i did with my last fuzz, and they seem to be fine.

[jrod]

Have you double checked the values of the other components? Your voltages are way off. The Q1 collector voltage should be about .5V and Q2 about 4.5V. I suggest checking to make sure all the resistor values are ok.

[philbinator1]

Have you double checked the values of the other components? Your voltages are way off. The Q1 collector voltage should be about .5V and Q2 about 4.5V. I suggest checking to make sure all the resistor values are ok.

thanks mate, willdo!   

[mac]

Q1 values are ok as silicons bias higher then germs.
Q2 collector resistors should be together 6k or so for typical 2n3904.

mac

[smallbearelec]

This article:

http://www.smallbearelec.com/HowTos/Breadboarding/Breadboard.htm

has some useful poop on lining up and tweaking a silicon FF. IMO 2N3904 is not best choice for either device in this pedal, and especially for Q1. Gain is usually too high to bias easily.

Regards
SD

[Gus]

try this for a Si FF type.
http://www.diystompboxes.com/pedals/gusJH2mod.gif

[joegagan]

try this for a Si FF type.
http://www.diystompboxes.com/pedals/gusJH2mod.gif

i'll second that. the coolest silicon ff i have ever tried.

[joegagan]

This article:

http://www.smallbearelec.com/HowTos/Breadboarding/Breadboard.htm

has some useful poop on lining up and tweaking a silicon FF. IMO 2N3904 is not best choice for either device in this pedal, and especially for Q1. Gain is usually too high to bias easily.

Regards
SD

steve, i had not seen that article before. very well done. should be required reading for newbies!

[philbinator1]

Well put!  I'm printing that off now, will read soon.  I fear breadboarding, but will look into it.  Need...learn...more...   

[Gus]

I meant to post this link
http://www.diystompboxes.com/pedals/gusFuzzFace.gif