Enclosure not stated · 3 knobs
Electro Harmonix Germanium ODVerified
Based on the Electro-Harmonix Germanium Overdrive· 3 other boards clone it
From the post
The EHX Germanium OD offers 60s overdrive tones using a combination of germanium and silicon transistors (all PNP). All 3 pots control the voltage is some way. The Bias pot controls the amount of voltage that reaches the Gain control, which in turn controls the remaining voltage that gets to the germanium transistor. The Volts control acts like a sag control on the overall voltage the circuit is running at, so you can emulate a dying battery. I've laid this out for on board pots mounted from the solder-side of the board using right angle PCB mount pots.
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 Effects Layouts (blog). No KiCad fragment has been drawn for this circuit yet.
Parts list 14 rows
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| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 5 | ||||
| ×4 | 62K | 62k | read from the layout by eye | |
| ×2 | 10K | 10k | read from the layout by eye | |
| ×1 | 2.2M | 2.2M | read from the layout by eye | |
| ×1 | 15K | 15k | read from the layout by eye | |
| ×1 | 100K | 100k | read from the layout by eye | |
| Capacitors 2 | ||||
| ×5 | 470nF | 470n | read from the layout by eye | |
| ×1 | 47uF | 47u | electrolytic; read from the layout by eye | |
| Diodes 1 | ||||
| ×1 | 1N4001 | 1N4001 | read from the layout by eye | |
| Transistors 3 | ||||
| Q1 | NKT275 | NKT275 | NKT275 or similar PNP germanium; read from the layout by eye | |
| Q2 | 2N5087 | 2N5087 | 2N5087, 2N3906, etc.; read from the layout by eye | |
| Q3 | 2N5087 | 2N5087 | 2N5087, 2N3906, etc.; read from the layout by eye | |
| Potentiometers 3 | ||||
| Gain | B10K | B10k | Potentiometer | read from the layout by eye |
| Bias | C100K | C100k | Potentiometer | read from the layout by eye |
| Volts | B100K | B100k | Potentiometer | read from the layout by eye |
Other boards based on the Electro-Harmonix Germanium Overdrive
- Electro Harmonix Germanium Overdrive Dirtbox Layouts
- Germanium OD PCBWay: Glory to Ukraine
- EHX Germanium Overdrive Tagboard Effects