The Vulcan is a heavy over to distortion by Joe Davisson. Check his Analog Alchemy page for more of his designs. Here’s a discussion of the circuit over at the DIYStompboxes forum.
I created a PCB you can order at OSH Park.
| Part | Value |
| C1 | 100n |
| C2 | 100n |
| C3 | 100n |
| C4 | 2n2 |
| C5 | 100n |
| C6 | 100n |
| C7 | 22µ |
| C8 | 22µ |
| C9 | 22µ |
| C10 | 100µ |
| C11 | 47n |
| D1 | 1N914 |
| D2 | 1N914 |
| D3 | 1N914 |
| D4 | LED |
| D5 | 1N5817 |
| Q1 | 2N5089 |
| Q2 | 2N5089 |
| Q3 | 2N5089 |
| GAIN | A1M |
| Volume | A100K |
| R1 | 1M |
| R2 | 1M |
| R3 | 4M7 |
| R4 | 10K |
| R5 | 1K |
| R6 | 470K |
| R7 | 1M |
| R8 | 4M7 |
| R9 | 10K |
| R10 | 1K |
| R11 | 470K |
| R12 | 1M |
| R13 | 4M7 |
| R14 | 10K |
| R15 | 1K |
| RLED | 1K-10K (adjust to taste) |
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