Enclosure not stated · 6 knobs
Fred Briggs P.A.F. Overdrive
Based on the Briggs' P.A.F. Overdrive· 1 other board clones it
- Category
- Overdrive
- Price
- see vendor
From the vendor
The blog author's expansion of the Tube Sound OD: an LF353 input buffer fixes the low input impedance, a Bass control around the input cap, a Gain pot in the emitter bypass, a Treble control, and a second op-amp stage with red LED clipping and a Boost control, ahead of the volume.
The author used a 50K bias trimmer in his build in place of the 20K. Simplified build: replace the 2.2n cap with 33n in series with 33K, drop the Bass control, bypass the Gain control for full gain, leaving Boost, Treble and Volume (Boost can be an internal trimmer). The Big Muff-style tone control from the BSIABII (as in the ZVex Box of Rock) also works in place of the Treble control, with the Bass control left out.
Schematic
The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.
Parts list 34 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 schematic was not sure of
- The electrolytic in series with the Bass pot has no readable value (only 'µ').
- The supply diode has no part number.
- The input resistor to Vr reads 510K.
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 12 | ||||
| R1 | 100 | 100 | supply; read from the schematic by eye | |
| R2 | 8.2K | 8.2k | Vr divider; read from the schematic by eye | |
| R3 | 10K | 10k | Vr divider; read from the schematic by eye | |
| R4 | 1M | 1M | read from the schematic by eye | |
| R5 | 510K | 510k | to Vr; read from the schematic by eye | |
| R6 | 220K | 220k | read from the schematic by eye | |
| R7 | 10K | 10k | read from the schematic by eye | |
| R8 | 10K | 10k | read from the schematic by eye | |
| R9 | 470 | 470 | read from the schematic by eye | |
| R10 | 510K | 510k | to Vr; read from the schematic by eye | |
| R11 | 3.3K | 3.3k | read from the schematic by eye | |
| R12 | 2.2K | 2.2k | read from the schematic by eye | |
| Capacitors 10 | ||||
| C1 | 220u | 220u | electrolytic; read from the schematic by eye | |
| C2 | 100n | 100n | input; read from the schematic by eye | |
| C3 | 2.2n | 2.2n | read from the schematic by eye | |
| C4 | ? | ? | electrolytic, in series with Bass; read from the schematic by eye | |
| C5 | 47u | 47u | electrolytic; read from the schematic by eye | |
| C6 | 100n | 100n | read from the schematic by eye | |
| C7 | 10n | 10n | read from the schematic by eye | |
| C8 | 100n | 100n | read from the schematic by eye | |
| C9 | 510p | 510p | read from the schematic by eye | |
| C10 | 1u | 1u | electrolytic; read from the schematic by eye | |
| Diodes 1 | ||||
| D1 | ? | ? | supply protection; read from the schematic by eye | |
| Transistors 2 | ||||
| Q1 | ? | ? | NPN, hFE matched with Q2; read from the schematic by eye | |
| Q2 | ? | ? | PNP, hFE matched with Q1; read from the schematic by eye | |
| ICs 1 | ||||
| IC1 | LF353 | LF353 | read from the schematic by eye | |
| Potentiometers 6 | ||||
| Bass | B100K | B100k | Potentiometer | rheostat; read from the schematic by eye |
| Bias trim | 20K | 20k | Potentiometer | trimmer; read from the schematic by eye |
| Gain | B1K | B1k | Potentiometer | read from the schematic by eye |
| Treble | B10K | B10k | Potentiometer | read from the schematic by eye |
| Boost | B50K | B50k | Potentiometer | read from the schematic by eye |
| Vol | B100K | B100k | Potentiometer | read from the schematic by eye |
| LEDs 2 | ||||
| D2 | LED | LED | red, clipping; read from the schematic by eye | |
| D3 | LED | LED | red, clipping; read from the schematic by eye | |
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