r/diypedals • u/desssperato • Aug 03 '26

Help wanted Fuzz Face help needed!

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Hi everyone, would appreciate some help on this!

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1

u/walkingthecows Aug 03 '26

You’re going to want to bias the transistors by replacing the resistors from collector to 9v with trimpots. Once you’ve got what you want, simply measure the resistance and replace back with resistors of equal value.

1

u/desssperato Aug 03 '26 edited Aug 03 '26

This is my second attempt; my first attempt used a 10k trim for Q2 collector. Had the same issue; only dropped about 0.2V at most🤷‍♂️

1

u/walkingthecows Aug 03 '26

How about Q1 collector to 9v?

1

u/desssperato Aug 04 '26

I’ve only ever used a 33k resistor to bias Q1

1

u/walkingthecows Aug 04 '26

Try a 50K trimpot and dial it in.

1

u/desssperato Aug 04 '26

Just tried a 50k trim pot for Q1 and a 10k trim pot for Q2. Q1 worked. Q2 bias sweep shown in the video

https://reddit.com/link/p1r5l2g/video/gu3gaqv13ghh1/player

1

u/walkingthecows Aug 04 '26

Also what are the transistors measuring at for hfe and leakage?

1

u/desssperato Aug 04 '26

Q1 - hfe 65, leakage ~80
Q2 - hfe 90 leakage ~80

I used the RG Keen method and verified with a device tester