JEN Fuzz PCB layout with Mods
resistors are 1/4 watt
C1 0.1uF metallised polyester
C2 0.1uF metallised polyester
C3 10uF radial electrolytic NP
50v (non polarised)
BC548B or 2N3904
BC548B or 2N3904
R3 10k approx
(adjust for half battery voltage on Q2 collector) (see
R3b jumper wire (see
VR1 100k linear pot controls fuzz level,
unity to full fuzz range, or soft to hard fuzz
1x Stereo 1/4" Jack Socket for
1x Mono 1/4" Jack Socket for output
1x 9v Battery Clip
linear pot for biasing transistor (see below)
NOTE: You only have to do this once for a pair
To get a fuzz that cleans up nicely when you turn down the
volume, you have to wire a pot (25k linear, middle and 1 outside lug) to where
R3 goes and adjust it until the voltage read on the collector of the Q2
transistor is half the voltage of the battery. Make sure the fuzz is
powered on when doing this and the jumper wire is soldered in place at
R3b. It also helps to wait a while (30 mins+) after you finish soldering
with the fuzz plugged in/turned on, so everything is at normal operating
temperature before and during taking any measurements.
1. Make sure the effect is
on/input plugged in, fuzz control on max gain.
Measure the voltage of the battery.
Measure pin C of Q2 transistor by placing 1 probe on ground
connection (-9v) and 1 probe on pin C of Q2
4. Now turn the pot until
you read half the voltage of the battery.
Then disconnect the pot from the circuit and measure its
6. Now place a resistor of
this value into R3.
want/need to be more precise, you can add the value of 2 resistors in series
by placing them in R3 and R3b positions (dont forget to remove the jumper wire
first in R3b!).
this will virtually guarantee a good sounding pick responsive fuzz with most
Mods: For more bass/lows, raise the value of C1 (input)
and/or C2 (output) capacitors. E.g. 0.22uF or 0.47uF.