125B · 3 knobs
Peppermill
Based on the Runoffgroove Peppermill
- Category
- Overdrive· JFET Overdrive
- Controls
- Drive · Tone · Volume
- Difficulty
- Easy
- Price
- $12.50in stock
From the vendor
A super-simple drive created by boosting the signal into a J201 JFET until it clips in a tube-like manner.
The Runoffgroove Peppermill is a simple circuit designed to showcase the tube-like clipping characteristics of the J201. It’s a very minimalist design which is composed of nothing more than a MOSFET gain-boost stage into a JFET. The gain can be adjusted between the two stages to control the amount of clipping, and an output volume is present at the end, and that’s it.
The Aion FX version of the Peppermill is a direct adaptation of the original circuit, with one modification: the addition of a tone control. The original circuit has a R-C lowpass filter right before the volume, and by making the resistor value adjustable, you end up with a useful tone control without otherwise affecting the original circuit.
Since the J201 is very difficult to find in TO-92 through-hole format, and many DIY hobbyists are intimidated by SMD parts, Aion FX offers J201s in SMD format that have been pre-soldered to adapters so they can be used as through-hole parts.
Schematic
The schematic is in the vendor's build document, page 5. Open the build document. No KiCad fragment has been drawn for this circuit yet.
Parts list 31 rows
Report a wrong parse| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 9 | ||||
| R1 | 1M | 1M | Metal film resistor, 1/4W | |
| R2 | 1M | 1M | Metal film resistor, 1/4W | |
| R3 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R4 | 1k | 1k | Metal film resistor, 1/4W | |
| R5 | 100k | 100k | Metal film resistor, 1/4W | |
| R6 | 1k | 1k | Metal film resistor, 1/4W | |
| R7 | 5k1 | 5.1k | Metal film resistor, 1/4W | |
| RPD | 2M2 | 2.2M | Metal film resistor, 1/4W | Input pulldown resistor. |
| LEDR | 4k7 | 4.7k | Metal film resistor, 1/4W | LED current-limiting resistor. Adjust value to change LED brightness. |
| Capacitors 7 | ||||
| C1 | 22n | 22n | Film capacitor, 7.2 x 2.5mm | |
| C2 | 68n | 68n | Film capacitor, 7.2 x 2.5mm | |
| C3 | 1uF | 1u | Electrolytic capacitor, 4mm | |
| C4 | 47n | 47n | Film capacitor, 7.2 x 2.5mm | |
| C5 | 2n2 | 2.2n | Film capacitor, 7.2 x 2.5mm | |
| C6 | 100uF | 100u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C7 | 100n | 100n | MLCC capacitor, X7R | Power supply filter capacitor. |
| Diodes 1 | ||||
| D1 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| Transistors 2 | ||||
| Q1 | 2N7000 | 2N7000 | MOSFET, N-channel, TO-92 | |
| Q2 | J201 | J201 | JFET, N-channel, TO-92 or SOT-23 | Can use either J201 (through-hole) or MMBFJ201 (SMD). |
| Potentiometers 3 | ||||
| TONE | 100kC | C100k | 16mm right-angle PCB mount pot | |
| GAIN | 250kB | B250k | 16mm right-angle PCB mount pot | |
| VOL. | 100kA | A100k | 16mm right-angle PCB mount pot | |
| Trimmers 1 | ||||
| BIAS | 50k | 50k | Trimmer, 10%, 1/4" | |
| Switches 1 | ||||
| FSW | 3PDT | 3PDT | Stomp switch, 3PDT | |
| LEDs 2 | ||||
| D2 | 3mm LED | 3MM LED | LED, 3mm, red diffused | |
| LED | 5mm | 5MM | LED, 5mm, red diffused | |
| Jacks & sockets 3 | ||||
| IN | 1/4" stereo | 1/4" STEREO | 1/4" phone jack, closed frame | Switchcraft 112BX or equivalent. |
| OUT | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| DC | 2.1mm | 2.1MM | DC jack, 2.1mm panel mount | Mouser 163-4302-E or equivalent. |
| Hardware 2 | ||||
| BATT | Battery snap | BATTERY SNAP | 9V battery snap | Optional. Use the soft plastic type—the hard-shell type will not fit. |
| ENC | 125B | 125B | Enclosure, die-cast aluminum | Can also use a Hammond 1590N1. |