More Fuzz: NPN/PNP compounds with schem and samples

[bioroids]

Hi!

Based on Pete Moore's idea of darlingtonize (?) low gain germaniums to make them usefull.
This uses a Sziklai compund (a darlington of NPN and PNP) to the same effect, on a Fuzz Face circuit.

You can check it out here : http://www.dedalofx.com/bioroids/ideas/idea_04.html

As a side effect this is a negative ground pedal, in spite of using PNP germaniums, thanks to the Sziklai connection. Another good news: low gain germaniums are way cheaper! and I think the germanium tone is retained even using silicon as the NPN part.

Luck

Miguel

[petemoore]

  Looks kool, Bio...
  I can't comment too much because I'm not figureing out how 'upside down' PNP's would work...IOW, I'm in the dark there...

[MartyB]

Nice sound clip Bioroids!

[petemoore]

  Wicked, sounds like...'pre-octave', a hint of wierdness in there.

[bioroids]

Thanks!

Yeah, sounds like the bias is sligthly off, or maybe is the excesive gain of the setup? I should check the wave on Cool Edit to see what's happening there.

I had to adjust bias several times, I think because of termal runaway.  I would have added some temperature compensation diodes if I only had some germaniums left!

If anyone can try this using really low gain germaniums, like 20-50 Hfe would be nice to hear the results.

Luck!

Miguel

[Paul Perry (Frostwave)]

If there was a 'post of the week', this would be hard to beat.
Idea #3 (simple trem) looks pretty good too.

[brett]

Hi.
Very cool design.
Have you tried low hFE transistors instead of the BC549s?  Like 2N2369As?
I think that the gain thru the first 549 will be large, but could be tamed by putting a small resistor (100 ohms, 470 ohms ) on the emitter.  Might be worth a try.
Wow.  Great work!!

[Peter Snowberg]

It's official then.....


This is the post of week. 



Very nice work!

I had never heard of Sziklai before. I love learning.

[MartyMart]

Very cool idea !
I love the sound of the sample.....
congrats
Marty.

[puretube]

type: > George Sziklai < into the "inventor"-field,
and get over 100 results from 1941 to 1985 from transistor over CTV to pattern recognition...

[Paul Perry (Frostwave)]

http://www.semiconductormuseum.com/Transistors/RCA/OralHistories/Herzog/Herzog_Page3.htm
can't remember what i did before the net..

[bioroids]

Thanks! you're making me 

It seems I only have medium to high gain transistors on my parts bin (waiting on Small Bear for the low Hfe germaniums). I'll check if I can get some of those 2N2369As over here too.

Very interesting links too, it seems like this Sziklai guy was very prolific (I had never heard of him before I run into this circuit).

I also tried with mixed results using a germanium diode in parallel with the PNP's base and emmiter, piggybacking style. I think this is worth exploring too.

Luck!

Miguel

[MartyB]

Here's a PCB layout for Miguel's 'MoreFuzz'  using the Szikali scheme:

http://aronnelson.com/gallery/MartyBs/Sziklailyt

I breadboarded it with all germaniums and really like it.  I'm using  2SC281's for Q1 /Q2 hFe 100-102, and SFT306's for Q3/Q4 hFe 17-29.

Cool project Miguel! 

[Yun]

i'd really love to try this build, man! 

Do you think i could get away with all silicon eh?  I'm out of PNP germs  . 

[MartyB]

I don't see why not.  The trick will be getting low enough gains I would think with silicon

[MartyB]

Should it be more fuzz, or Moore fuzz?

[petemoore]

   LOL...OFten when it comes to Fuzz... 'The Moore, the merrier' !!!

[Dragonfly]

Here's a PCB layout for Miguel's 'MoreFuzz'  using the Szikali scheme:

http://aronnelson.com/gallery/MartyBs/Sziklailyt

I breadboarded it with all germaniums and really like it.  I'm using  2SC281's for Q1 /Q2 hFe 100-102, and SFT306's for Q3/Q4 hFe 17-29.

Cool project Miguel! 

nice work marty....


miguel...i'm gonna have to build this one...great job !

thanks,
andy

[Dragonfly]

I also tried with mixed results using a germanium diode in parallel with the PNP's base and emmiter, piggybacking style. I think this is worth exploring too.

Luck!

Miguel

miguel...

you might also try running a germanium diode to ground from q1's emitter ...softens up the signal a bit, and adds a little "sponginess"...its something ive been playing around with a bit...

andy

[bioroids]

Hi!

Very cool Marty thanks for sharing the layout! 
How does it sound with all Germaniums? I think that would be the unheard  high gain Ge sound.
Beware of leakage though!

You can call it More Fuzz, or Moore Fuzz, Sziklai Fuzz would be apropiate too. I'm terrible at names so better pick it up yourself

Would be nice to hear build reports using different gain/transistors too. Brett has recommended 2N2369A for low gain silicon.

Luck!

Miguel