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Based On
Runoffgroove Peppermill
Effect Type
JFET Overdrive
Build Difficulty
Project Summary
A super-simple drive created by boosting the signal into a J201 JFET until it clips in a tube-like manner.
Peppermill printed circuit board

Printed Circuit Board

What's included?
PCB only. Build instructions and parts list can be viewed or downloaded from this page.


In stock

Complete Kit

Not yet available.
Kits are developed based on interest, so if you’d like to see one for this project, let us know.
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Project overview

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.