This Week on the Breadboard: The Spirit in the Sky Fuzz

[Chuck D. Bones]

Mode 4 allows Q2 to be biased at or near saturation. The FUZZ pot not only varies the gain. it also varies the bias.

 

[Chuck D. Bones]

Here's an alternate BIAS circuit:


Q1 HFE ~ 100
Q2 HFE ~ 140

 

[Cybercow]

So place the 22k between the collector and BIAS-1, or betwixt BIAS-3 and the gate?
Based on the discussion thus far, I imagine it should be the former (green below) not the latter (blue below):

View attachment 119560

Hm I think I thinkered it out, should be the green.

Green is certainly the easiest. Blue entails cutting a trace cuz lugs #2 & #3 are joined on the PCB.

 

[genXslacker]

Here's an alternate BIAS circuit:

View attachment 120748
Q1 HFE ~ 100
Q2 HFE ~ 140

I'm away from home for a few more days, but that's going on a breadboard as soon as I get one in arm's length.

 

[Chuck D. Bones]

One more mod. It lets us set the SUSTAIN lower if we want. Maybe nobody does. Max sustain is the same. I also reduced C1.

 

[genXslacker]

It lets us set the SUSTAIN lower if we want. Maybe nobody does. Max sustain is the same.

To me, more choice is always better on a pot, so long as it's functional. The only thing I don't like is when a pot lets me paralyze an LFO or something like that... not an issue here, obviously.

I'm really eager to get these on a breadboard. I'm in the cult that is obsessed by the tone on the record.

 

[Feral Feline]

Green is certainly the easiest. Blue entails cutting a trace cuz lugs #2 & #3 are joined on the PCB.

View attachment 120760

Agreed GREEN is the way to go, as stated in my post, but if blue — NO NEED TO CUT A TRACE!

Should I have gone for blue I'd simply use a solder-lug pot (or simply not solder legs 2&3 to the board — tie lugs/legs 2&3 together on the pot and run the resistor to the Q2-side of C4. Lug 1 as it is, of course.


Nonetheless, I think we're green, Super, even...

 

[Cybercow]

Agreed GREEN is the way to go, as stated in my post, but if blue — NO NEED TO CUT A TRACE!

Should I have gone for blue I'd simply use a solder-lug pot (or simply not solder legs 2&3 to the board — tie lugs/legs 2&3 together on the pot and run the resistor to the Q2-side of C4. Lug 1 as it is, of course.


Nonetheless, I think we're green, Super, even...

Ghak! I missed that entirely. I guess my reading comprehension is now fully exposed. Green indeed.

 

[Cybercow]

One more mod. It lets us set the SUSTAIN lower if we want. Maybe nobody does. Max sustain is the same. I also reduced C1.

View attachment 120766

Challenge accepted!
I'm currently building out to Overcast Fuzz boards, so I thought I'd try to adapt CB's 0.1.1 mods to one of them. Now I'm just trying to find some low Hfe NPN BJTs in my stock. All 98 of the 2N2222s I have measure higher than 160 on my Peak Atlas DCA75.

UPDATE: Found a coupla 2N3566 BJTs with Hfe's @ 96 & 105 for Q1 & Q2 respectively. With CB's changes this thing sounds great!

UPDATE AGAIN: I'm definitely modding the 2nd Overcast circuit to match CB's 0.1.1 changes. Awesome!