The Hi-Lo Fuzz...

[m_charles]

Hoping someone will give this a go and see if they like the results!
I posted before about uses for low hfe ge's, so this is my first go at it.



Credits are too numerous, but all the usual suspects (keen, gagan, dragonfly, etc. etc.).

This could alternately be called YAAAAAAAAFF.

Hope it helps someone!
-chuck

[m_charles]

guess no-one cares about my little schem. poor me... boo hoo..

[Chugs]

Sound clips? What's the lowest hfe you have tried? I think I got some Ge transistors in the 25-30 hfe range lying around. It would be nice to put them to use.

[John Lyons]

Not a criticism but other than the lower resistance (22K) off Q1 how is the circuit designed
to use low Hfe Transistors? The other values are fairly common.
Just wondering...

John

[m_charles]

Not a criticism but other than the lower resistance (22K) off Q1 how is the circuit designed
to use low Hfe Transistors? The other values are fairly common.
Just wondering...

John

IT IS NOTHING LIKE ANY OTHER FUZZ EVER INVENTED! kidding of course. Well its a fuzzface. After all the tweaks to this circuit pretty much any value can be considered "common". And none of the tweaks are groundbreaking I know. but compared to a regular old FF, the 33k, 470, the 8.2K, the in and out caps, the gain auto-maxed @ 1.2k and controlled with the variable resistor on the front (ala gagan ez fuzz) are all "different". Again, I'm not saying I came up with these "amazing" tweaks, I just fiddled with various FF mods, cap and resistor values and found that for the low hfe Q1, and high (for germanium) Q2, pushing the 33K down to 22K, setting the trim at Q2's collector, somewhere in the vacinity of 5-6K, (prob. could have made it a 10k trimmer), stealing rg's small cap from c-b at Q2. I think all these little tweaks are worthy of being called "different". sounds good. breadboard it and see if u agree.

[PRR]

Minimum Hfe for Q1 is about 5. (Turn Trim to zero, Q2 saturates near 5V collector 4V Emitter, 3.75V drop in 100K gives large 0.04mA base current, Q1 collector current is near 0.2mA. 0.2/0.04 is 5.)

I'm not sure what it sounds like at this point; you may need hFe>10 and a different trim-goal to get "the sound".

hFe to infinity is fine either part.

It does not handle leakage "well" (by modern design standards).