Mister Fuzz not F..uzzing

johnzero0

Member
Hi Guys,

i wonder if you can help i just built a Mister Fuzz and ordered in some equivalent PNP 2N270 germanium transistors but im just getting high gain / distortion no real fuzztone. I am using sockets so have swapped them around in different positions on the board but i‘m just not getting the fuzz.

i measured hfe for them using my meter
i get 150, 874, and 611.

There is also a voltage inverter bypass below the board which says see the build docs but i cant see any reference to it in the build documents.
 

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Well, i put some different Ge transistors in previously i had ac151s in and am getting a reasonably good sounding psychotic reaction / satisfaction style fuzz. Is there any tweaking i can do eg substituting trimmers for resistors for dialing it in?
 
I’m no pro, so take this for what’s it’s worth…

I think your first set of transistors (Ac151s ?) hfe were to high… stuff I’ve read about fuzz circuit usually talks about hue of 30-150…

From what I understand you want lower hfe in the first fuzz stage and a higher one in the second stage.

For the voltage inverter, looks like that‘s for Sw1:


16F03080-1D10-44D8-BC49-8457E1E27DD7.jpeg
Does it look Like you could mount a on/off switch on that part of the board ?
 
Leakage also plays a ginormous role in the FZ-1. You could have perfect hfe, but if your first two transistors aren’t leaky enough, the pedal won’t work right…
 
Does it look Like you could mount a on/off switch on that part of the board ?
Thanks for looking Egrenier your more of a pro than I am, Its in my second picture of the underside of the board there is a square shape inside are 2 pads, in my limited understanding its for substituting npn transistors in but not sure if any of the other components will need to be reversed also if its inverted.

interesting about the hfe, ill check the hfe of the ones i put in.

Leakage also plays a ginormous role in the FZ-1. You could have perfect hfe, but if your first two transistors aren’t leaky enough, the pedal won’t work right…


so it really more depends on leakage of the first 2 from left to right? 3rd just has to be the right value hfe?
 
The voltage inverters on PPCB PNP circuits are sometimes included for the convenience of being able to use your standard pedalboard power supply. Some people choose to not include the extra circuitry and run it from a dedicated/isolated power source. If that is the case, then you omit the charge inverter and put a small jumper across the pads in the square. @Robert is that the case for this circuit, or is this for in case you wish to use a different charge pump chip?
 
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