Silicon Fuzz Face

Silicon Fuzz Face
Has anyone got any tips on how to build a silicon fuzz face using BC108 or BC109. Whenever i try this they just oscillate at full fuzz. Are the modern day transistors too high gain to work?

I built a version of the sili-face shown on runoffgroove.com about a year ago with some inevitable variations eg. swapped a few capacitor values that I didn't have and lost the 4K7 resistor. Also put the 2 collector resistors as trim pots for tuning the 2 BC108C's I used. It seems to work fine - its fuzzy and pretty loud too!! If you want a completely mental uncontrolable silicon fuzz try building Aaron Nelson's "Hornet" with what's lying around!!!!

Hey tatter I got some BC108 and they're great. Used them to build on a BYOC pcb and sourced all my own parts. They sound pretty sweet. Small bear have em. http://www.smallbearelec.com/Detail.bok?no=272

Hey tatter I got some BC108 and they're great. Used them to build on a BYOC pcb and sourced all my own parts. They sound pretty sweet. Small bear have em. Cheers Ted. I got a load of BC108 and BC109C off ebay. My hfe values are 300-400 for the BC108s and the BC109C are even higher (450+) are these the sort of gains you're working with? I haven't mocked it up yet but when i put them in my BYOC Fuzz Face i got oscillation at full fuzz. Are yours lower gain than mine or am i just being over cautious and just get stuck in an build the thing?

Shit tatter, I'm sorry I'm just not as advanced as you when it comes to measuring gain. I just stuck 'em in! :)

I need to get one of those component measuring tingy's from maplin as I also bought a shit load of mullard / other NOS trannies for experimenting with. But I've just bought a frigging house so my mind is on different sort of DIY.

Yeah that's all i've got, so you can't be less advanced than me, i'm a fuzz amoeba! I'll just shove 'em in and see what happens, i might try trimmers on the collectors like Philm suggested as well. I really should make a proper effort to work out leakage but my brain already hurts just following schematics.

Re: Silicon Fuzz Face
Has anyone got any tips on how to build a silicon fuzz face using BC108 or BC109. Whenever i try this they just oscillate at full fuzz. Are the modern day transistors too high gain to work? Buy some BC182L's :lol: Much less prone to oscillation even at full tilt. Original silicon Fuzz Face's tend to oscillate. I think the only one I had that didn't had BC183L's.

Thanks again Captain! Just found some of those on ebay!

BC183's, as suggested are nice if you use BC108 or BC109 and theyre high hfe, try a 100 ohm resistor between Q1's emmitter and ground, a 100 ohm resistor between the FUZZ pot lug 1 and ground, and a small (47-100pf) cap between Q1 collector and base... usually that cures any oscillations

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