Enclosure not stated · 3 knobs
Fuzzhead Fx Box of Germanium Mk. IIVerified
Based on the Fuzzhead Fx Box of Germanium Mk. II
From the post
An updated version of a project I was tinkering with a couple of years ago. The idea was basically to find some use for some low leak USSR germaniums other than in Fuzz faces, Rangemasters and Tonebenders, And to do a germanium version of Zvex Box of Rock. Some biasing tweaks was necessary since BJT Ge's is a completely different animal to MOSFETs but the cap values in the signal path is more or less identical. Couldn't resist to add Boost switch so you can use it as a fuzz as well...and decrease the value of the low pass filter cap in the tonestack to 12nF since I found it a bit muddy with 22nF.
First version was positive ground but I used normal power supply for this version since I have to many unused MP38A transistors but other fairly low gain and low leak NPN germaniums should work as well.
Schematic
This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Dirtbox Layouts. No KiCad fragment has been drawn for this circuit yet.
Parts list 30 rows
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| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 10 | ||||
| ×1 | 47Ω | 47 | read from the layout by eye | |
| ×1 | 180Ω | 180 | read from the layout by eye | |
| ×2 | 9.1K | 9.1k | read from the layout by eye | |
| ×1 | 39K | 39k | read from the layout by eye | |
| ×1 | 47K | 47k | read from the layout by eye | |
| ×2 | 51K | 51k | read from the layout by eye | |
| ×1 | 82K | 82k | read from the layout by eye | |
| ×1 | 470K | 470k | read from the layout by eye | |
| ×3 | 1M | 1M | read from the layout by eye | |
| ×1 | 2.2M | 2.2M | read from the layout by eye | |
| Capacitors 12 | ||||
| ×1 | 100pF | 100p | read from the layout by eye | |
| ×1 | 330pF | 330p | read from the layout by eye | |
| ×1 | 470pF | 470p | read from the layout by eye | |
| ×2 | 2.2nF | 2.2n | read from the layout by eye | |
| ×2 | 10nF | 10n | read from the layout by eye | |
| ×1 | 12nF | 12n | read from the layout by eye | |
| ×2 | 22nF | 22n | read from the layout by eye | |
| ×2 | 100nF | 100n | one drawn as a ceramic, one as a film box; read from the layout by eye | |
| ×1 | 680nF | 680n | read from the layout by eye | |
| ×1 | 2.2uF | 2.2u | electrolytic; read from the layout by eye | |
| ×1 | 10uF | 10u | electrolytic; read from the layout by eye | |
| ×1 | 100uF | 100u | electrolytic; read from the layout by eye | |
| Diodes 1 | ||||
| D1 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 3 | ||||
| Q1 | MP38A | MP38A | or other low leak NPN Ge, Hfe 60-80; read from the layout by eye | |
| Q2 | MP38A | MP38A | or other low leak NPN Ge, Hfe 60-80; read from the layout by eye | |
| Q3 | MP38A | MP38A | or other low leak NPN Ge, Hfe 60-80; read from the layout by eye | |
| Potentiometers 3 | ||||
| Gain | B10K | B10k | Potentiometer | read from the layout by eye |
| Tone | B100K | B100k | Potentiometer | read from the layout by eye |
| Volume | B100K | B100k | Potentiometer | read from the layout by eye |
| Switches 1 | ||||
| Switch | SPST | SPST | toggle; read from the layout by eye | |