Retro Channel Fuzz Question

[soggybag]

Someone sent me this yesterday. It looks really interesting. It's sort of a Tone Bender built from a 3086/3046 transistor array.

There were a couple things going on here that I don't recognize.

First D2 and pins 12, 13, and 14. Not sure what this is doing. My guess is that it doesn't do anything for the audio and is there to ground the substrate. I'm not sure why this is needed. But I have read it prevents damaging the chip.

The two transistors at the input pins 1, 2, 3, 4, and 5. The first transistor (pins 3,4,5) make sense but what is happening with the second transistor (pins 1, 2, 3)? Is this sort of a NPN mu-amp?

[PRR]

D2 T5 is just a 1.2V reference.

The whole connection around T1-T2 is a datasheet example of bias based on the excellent matching of parts on the same IC chip. It works but not so well with loose BJTs.

T3 T4 is of course a variant Fuzz Face.

[idy]

I think you call those T1 and T2 together a "long-tailed pair."

[antonis]

I think you call those T1 and T2 together a "long-tailed pair."

Not without a tail..
(T1 & T2 Emitter common resistor..)

[PRR]

The T1-T2-T5 affair can be derived from Fig 2-19 B and D in Walt Jung's "IC Array Cookbook". This is not in public domain, and Walt pursues infringers. His website says "This book is currently available as an Ebook. For information, send email to
<Ebooks@waltjung.org>" but I do not know if this information is current. The IC Array Cookbook is readily available on ABE and Amazon and other used-book markets.
https://www.abebooks.com/9780810407626/IC-array-cookbook-Jung-Walter-0810407620/plp
https://www.amazon.com/IC-array-cookbook-Walter-Jung/dp/0810407620

Do not confuse with IC Chef Cookbook which is about food and drink, who knew?

[PRR]

I think you call those T1 and T2 together a "long-tailed pair."

Like my Corgi: no tail.

(Yes, some don't some do. The 8 Corgi House has 6 tails.)

[iainpunk]

The T1-T2-T5 affair can be derived from Fig 2-19 B and D in Walt Jung's "IC Array Cookbook". This is not in public domain, and Walt pursues infringers. His website says "This book is currently available as an Ebook. For information, send email to
<Ebooks@waltjung.org>" but I do not know if this information is current. The IC Array Cookbook is readily available on ABE and Amazon and other used-book markets.
https://www.abebooks.com/9780810407626/IC-array-cookbook-Jung-Walter-0810407620/plp
https://www.amazon.com/IC-array-cookbook-Walter-Jung/dp/0810407620

Do not confuse with IC Chef Cookbook which is about food and drink, who knew?

why would someone call a book on food and drinks a cook book? theres no soldering involved in food, is there?

thats an interesting take on a loose approximation of something inspired by a vague description of a Mk2 Tone Bender! cool

cheers

[PRR]

> why would someone call a book on food and drinks a cook book?

Eet Smakelijk!

[iainpunk]

> why would someone call a book on food and drinks a cook book?

Eet Smakelijk!

dankjewel

cheers