1590B · 6 knobs
Madferret Germageddon
Based on the Madferret Germageddon
From the post
Madferret's amazing and complete overhaul of those circuits that use low gain Ge transistors in darlington configuration to achieve fuzzy germanium bliss. This baby consumes 6 of your low gain/low loeak germaniums and adds not-completely-unlike big muff tone stack plus a recovery stage to keep the signal loud. Not to mention three different pots to tune it to your liking - including Choke control, Pregain and first stage Iintensity controls. It has six knobs, so you might want to use a big box for it. Or if you're feeling adventurous, you can always try it out with 9mm pots and fit it in a 1590B :)
This one uses negative power supply, so wire it for battery only or use appropriate charge pump.
From Madferret: Credit where credit's due by the way, this was based off the Germocide layout by Dragonfly, with ideas taken from all over the internet from places like DIYstompboxes, AMZ etc but especially from Mark's blog as I seriously wouldn't have a clue about making pedals if it weren't for all the information from this site and all the input from everyone that uses it. Go team!
Possible mods:
-To get more gain from the recovery stage, decrease the value of 3K3 resistor coming from Q7 emitter, or increase the value of 15K at the Q7 collector. Or do both.
-If there's too much fizz, try upping the 100p cap to 220p or 470p
-Lowest settings of Pregain and Intensity can be tweaked by swapping the 18K resistors for something like 4K7 or 10K.
(update 18.10.2019 - On the layout, there is a 100K resistor missing from the Q7 base to ground. This resistor can be fitted to get the circuit running as intended. I lost my source files in '16, so to remedy this, i'd need to do a redraw. I may do it soonish... However, the layout is otherwise verified. Thanks to ColoradoSynthDoctor for verifying it and noticing the error!)
Madferret's demo:
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 Tagboard Effects. No KiCad fragment has been drawn for this circuit yet.
Parts list 32 rows
Report a wrong parseGot parts in a drawer? See what you can build with them.
Check before you build · 2 values the reader of this layout was not sure of
- 28K at the bottom centre, left of the 15K: printed clearly, unusual value
- 100pF between Q5 and Q6 at the top: text overlaps the part outline, read as 100pF
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 13 | ||||
| ×4 | 220Ω | 220 | read from the layout by eye | |
| ×3 | 470K | 470k | read from the layout by eye | |
| ×2 | 18K | 18k | read from the layout by eye | |
| ×1 | 100K | 100k | read from the layout by eye | |
| ×1 | 27K | 27k | read from the layout by eye | |
| ×1 | 28K | 28k | read from the layout by eye | |
| ×1 | 15K | 15k | read from the layout by eye | |
| ×1 | 10K | 10k | read from the layout by eye | |
| ×1 | 3.3K | 3.3k | read from the layout by eye | |
| ×1 | 2.2K | 2.2k | read from the layout by eye | |
| ×1 | 1K | 1k | read from the layout by eye | |
| ×1 | 1M | 1M | read from the layout by eye | |
| ×1 | 100Ω | 100 | read from the layout by eye | |
| Capacitors 8 | ||||
| ×5 | 100nF | 100n | read from the layout by eye | |
| ×1 | 10nF | 10n | read from the layout by eye | |
| ×1 | 15nF | 15n | read from the layout by eye | |
| ×1 | 1.5nF | 1.5n | read from the layout by eye | |
| ×1 | 1uF | 1u | read from the layout by eye | |
| ×1 | 100pF | 100p | read from the layout by eye | |
| ×2 | 47uF | 47u | electrolytic; read from the layout by eye | |
| ×1 | 22uF | 22u | electrolytic; read from the layout by eye | |
| Diodes 1 | ||||
| D1 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 2 | ||||
| ×6 | PNP Ge | PNP GE | Q1-Q6, low leak, low gain PNP Ge transistors (hFE ~30-60); read from the layout by eye | |
| Q7 | 2N3906 | 2N3906 | 2N3906 or similar; read from the layout by eye | |
| Potentiometers 6 | ||||
| PreGain | A100K | A100k | Potentiometer | read from the layout by eye |
| Choke | B100K | B100k | Potentiometer | read from the layout by eye |
| Intensity | A100K | A100k | Potentiometer | read from the layout by eye |
| Fuzz | B2K | B2k | Potentiometer | read from the layout by eye |
| Tone | B100K | B100k | Potentiometer | read from the layout by eye |
| Volume | A100K | A100k | Potentiometer | read from the layout by eye |
| Trimmers 1 | ||||
| ×1 | 22K | 22k | read from the layout by eye | |
| Switches 1 | ||||
| Bass Cut | SPDT on/on | SPDT ON/ON | toggle; read from the layout by eye | |