The circuit inside every guitar pedal
A one transistor clean boost that makes a guitar about twenty times louder, with a volume knob. The core of most pedals.
Free build sheet
The parts, every wire with its length and bend points, a bend guide, both sides of the board and checkboxes to track your progress. Print it or keep it open at the bench.
Open the build sheetWhat you need
11 parts on a perfboard 17 × 30 holes, plus hookup wire.
| Qty | Part | Where to buy |
|---|---|---|
| 2 | Ceramic Cap100nF C1, C2 | Buy Ceramic Cap on Amazon |
| 1 | Power Input (2-pin) J1 | |
| 2 | Screw Terminal 2P (5.08mm) J2, J3 | |
| 1 | NPN Transistor (TO-92) Q1 | Buy NPN Transistor (TO-92) on Amazon |
| 1 | Potentiometer Q2 | |
| 1 | Resistor (axial)430k R1 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)10k R2 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)390 R3 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)43k R4 | Buy Resistor (axial) on Amazon |
Check every pin against the datasheet of the exact part in your hands before wiring.
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Cut list
11 wires, 312 mm (12.3 in) in total, in the order the build sheet cuts them. Wire numbers match the build sheet. Each length includes 5 mm per end to go through the hole.
| Wire | Colour and net | Length | ||
|---|---|---|---|---|
| 6 | Black9V N12 → M5 | N12 → M5 | 30mm | 23mm (90°) |
| 11 | BlueGND G6 → N3 | G6 → N3 | 35mm | 13mm (90°) |
| 5 | Blue9V D11 → O11 | D11 → O11 | 38mm | Straight |
| 4 | GreenCOLLECTOR N16 → J16 | N16 → J16 | 20mm | Straight |
| 10 | GreenGND M18 → H7 | M18 → H7 | 51mm | 33mm (90°) |
| 1 | RedOUT G25 → F26 | G25 → F26 | 14mm | Straight |
| 7 | RedGND C23 → F23 | C23 → F23 | 18mm | Straight |
| 3 | WhiteIN F13 → D7 | F13 → D7 | 30mm | 10mm (90°) |
| 9 | WhiteGND E24 → K18 | E24 → K18 | 40mm | 20mm (90°) |
| 2 | YellowVOL I21 → I24 | I21 → I24 | 18mm | Straight |
| 8 | YellowGND F25 → H26 | F25 → H26 | 18mm | 10mm (90°) |
About this build
A one transistor guitar booster, using the same topology as the Electro-Harmonix LPB-1. One NPN transistor, four resistors, two 100nF coupling caps and a 100k volume pot make a guitar about twenty times louder.
The guitar comes in on a screw terminal and goes through a coupling cap to the transistor's base. The resistors bias the transistor and set its gain, and the second coupling cap passes the boosted signal on to the volume pot. The caps block the DC, so only the guitar signal goes in and out.
9V comes in at the top and the amp output leaves at the bottom. The transistor is a TO-92 part and lead orders vary between makers, so wire it from the build sheet and the datasheet.
Electro-Harmonix and LPB-1 are trademarks of their owner. PerfBoard is not affiliated with or endorsed by Electro-Harmonix.
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