diy electronic music and gear from sk / cz


DIY audio electronics

Piezo preamp with EQ

Second version of my piezo preamp. Much more professional project using KiCAD, LTSpice, SMD technology and proper PCB design. Features charge amp with switchable gain, low-pass filter, Baxandall EQ with switchable center, adjustable battery indicator, MOSFET reverse polarity protection and ESD protection.

Github: link

Pedal-sized analog mixer

3x stereo IN, 2x stereo OUT. VOL+BAL for each IN channel. Ambler tone tilt for SUB OUT. DC IN 9-18V. Schematics mostly compiled from Small Signal Audio Design by Douglas Self. My most complex stripboard project - showed me the necessity to learn PCB design.

Electrifying a kantele

DIY piezo microphone + appropriate piezo preamp with baxandall EQ and volume control for a small cheap kantele for children. Also featuring a "smart" battery indicator. Schematics compiled from Elliott Sound Products, freecircuits etc.

Klon Centaur + DOD 410

Dual effect pedal. Legendary Klon Centaur on the left with mods to choose between different soft and hard clipping options. DOD 410 Boost on the right. Central switch to change the order of the effects.

Sub oscillator

Sub oscillator to make Behringer Crave sound fatter. Accepts triangle or square wave on the input and outputs a square wave 1 or 2 octaves lower (or a mix between them). Schematic by Carmello Azzarello.

ProCo Rat + EQD Talons

Dual effect pedal. ProCo Rat on the right with several mods and clipping options. Earthquaker Devices Talons on the left, also with clipping options. Central switch to change the order of the effects.

Midi thru box

MIDI data from the input is opto-coupled and repeated to five outputs. Featuring 9V thru port. Schematic by Morocco Dave.

Passive tone control

Boosting or attenuating low or high frequencies with adjustable cutoff point and (admittedly not very useful) LED clipping of low or high frequencies.

Expression knob

A simple expression knob I needed for my Empress ZOIA. Works the same way as an expression pedal, just with a knob.