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Fred Briggs Unknown Fuzz

Based on the Briggs' Unknown Fuzz· 1 other board clones it

Category: Fuzz
Controls: Bass Cut · hFE trim · Width · Bias trim · Volume
Price: see vendor

Read the post at Revolution Deux Schematic image

From the vendor

The blog author's own silicon fuzz, grown out of experiments with the Vox Tone Bender. The first stage is a pair of piggy-backed high-gain 2N5088s trimmed to an hFE of about 25 to act like a low-gain germanium device, driving a NOS BC108 second stage. There is no gain control; the guitar's volume knob takes it from mild overdrive to full fuzz, and the author describes it as fat and warm rather than harsh.

Add a 2n2 cap in parallel with the 22K resistor and the Width pot to calm the high end and upper mids; the author used it in his final build. Piggy-backed transistors are picky; you may have to try several pairs of 2N5088 before one works well.

Schematic

The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.

Parts list 21 rows

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Ref	Value	Normalized	Type	Notes
Resistors 6
R1	1M	1M		input pulldown; read from the schematic by eye
R2	15K	15k		input; read from the schematic by eye
R3	15K	15k		Q1 collector; read from the schematic by eye
R4	22K	22k		feedback; read from the schematic by eye
R5	1.8K	1.8k		Q2 collector; read from the schematic by eye
R6	1K	1k		Q2 emitter; read from the schematic by eye
Capacitors 6
C1	47u	47u		electrolytic, supply filter; read from the schematic by eye
C2	4.7n	4.7n		input; read from the schematic by eye
C3	1u	1u		electrolytic, in series with Bass Cut; read from the schematic by eye
C4	470p	470p		Q2 collector to base; read from the schematic by eye
C5	10u	10u		electrolytic, emitter bypass; read from the schematic by eye
C6	100n	100n		output; read from the schematic by eye
Diodes 1
D1	1N4007	1N4007		polarity protection; read from the schematic by eye
Transistors 3
Q1a	2N5088	2N5088		piggy-backed pair; read from the schematic by eye
Q1b	2N5088	2N5088		piggy-backed pair; read from the schematic by eye
Q2	BC108	BC108		hFE about 150; read from the schematic by eye
Potentiometers 5
Bass Cut	B100K	B100k	Potentiometer	read from the schematic by eye
hFE trim	100K	100k	Potentiometer	trimmer, adjust Q1's hFE to 25; read from the schematic by eye
Width	B100K	B100k	Potentiometer	feedback; read from the schematic by eye
Bias trim	10K	10k	Potentiometer	trimmer, bias Q2's collector to about 4.5V; read from the schematic by eye
Volume	A500K	A500k	Potentiometer	read from the schematic by eye

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