Enclosure not stated · 3 knobs
Electro Harmonix '75 Unknown MuffVerified
Based on the Electro-Harmonix '75 Unknown Muff
From the post
Here's a layout for a big muff from a schematic from October 15, 1975. It's known as the mystery muff. Should be a nice addition to any muff collection.
The only deviation from the schematic is that I added the mids switch, I changed the 1uF caps to polys instead of electrolytics, and added a polarity protection diode. The transistors are unknown so I looked at the schematic for muffs of a similar vintage and they used BC239C's, but you can and may use more common Si transistors like 2N5088, 2N5089, etc. The diodes are also unmarked, as they were unknown from this vintage so I marked them as the common 1N914/1N4148's, but you can try other Si diodes.
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 · 3 values the reader of this layout was not sure of
- 4nF at column I rows F-H: printed clearly, unusual value
- 500pF x3: printed clearly, unusual value
- Q1-Q4: legend says the original type is unknown; BC239C entered as the first part named
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 12 | ||||
| ×4 | 100k | 100k | read from the layout by eye | |
| ×1 | 22k | 22k | read from the layout by eye | |
| ×1 | 2.2k | 2.2k | read from the layout by eye | |
| ×2 | 39k | 39k | read from the layout by eye | |
| ×3 | 470k | 470k | read from the layout by eye | |
| ×3 | 100r | 100 | read from the layout by eye | |
| ×1 | 1k | 1k | read from the layout by eye | |
| ×1 | 10k | 10k | read from the layout by eye | |
| ×1 | 390k | 390k | read from the layout by eye | |
| ×2 | 15k | 15k | read from the layout by eye | |
| ×2 | 8.2k | 8.2k | read from the layout by eye | |
| ×1 | 12k | 12k | read from the layout by eye | |
| Capacitors 7 | ||||
| ×5 | 1uF | 1u | read from the layout by eye | |
| ×3 | 100nF | 100n | read from the layout by eye | |
| ×3 | 500pF | 500p | read from the layout by eye | |
| ×1 | 4nF | 4n | read from the layout by eye | |
| ×2 | 10nF | 10n | one on the board, one on SW1 (Boost); read from the layout by eye | |
| ×1 | 4.7nF | 4.7n | on SW1 (Flat); read from the layout by eye | |
| ×1 | 100uF | 100u | electrolytic; read from the layout by eye | |
| Diodes 5 | ||||
| D1 | 1N914 | 1N914 | read from the layout by eye | |
| D2 | 1N914 | 1N914 | read from the layout by eye | |
| D3 | 1N914 | 1N914 | read from the layout by eye | |
| D4 | 1N914 | 1N914 | read from the layout by eye | |
| D5 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 4 | ||||
| Q1 | BC239C | BC239C | Unknown, BC239C used in 75 Violet, can try 2N5088, 2N5089, etc.; read from the layout by eye | |
| Q2 | BC239C | BC239C | Unknown, BC239C used in 75 Violet, can try 2N5088, 2N5089, etc.; read from the layout by eye | |
| Q3 | BC239C | BC239C | Unknown, BC239C used in 75 Violet, can try 2N5088, 2N5089, etc.; read from the layout by eye | |
| Q4 | BC239C | BC239C | Unknown, BC239C used in 75 Violet, can try 2N5088, 2N5089, etc.; read from the layout by eye | |
| Potentiometers 3 | ||||
| Volume | B100K | B100k | Potentiometer | read from the layout by eye |
| Tone | B100K | B100k | Potentiometer | read from the layout by eye |
| Sustain | B100K | B100k | Potentiometer | read from the layout by eye |
| Switches 1 | ||||
| SW1 | SPDT on/off/on | SPDT ON/OFF/ON | toggle: Flat / Scoop / Boost; read from the layout by eye | |