Most oscillator projects you come across start at the finished end: a designed PCB, a panel, a calibration ritual. This one walks the opposite road. A sawtooth core is laid down on a single breadboard with a short list of cheap parts, and every component gets explained as it enters the circuit. For anyone who has wanted to get into DIY synths but felt locked out by jargon, this seems like a genuinely good entry point.
The core itself is built around a 40106 working as the Schmitt trigger inverter, with an RC network charging and discharging against ground to make a repeating sawtooth. A TL074 covers the op amp duty, and a TL072 is listed as a swap since only one op amp is actually needed. Power comes from either two 9V batteries with clips or a dual supply in the 9 to 15V range. The rest of the bill of materials stays delightfully short: four 100k resistors, one 1N4148 diode, a 1 uF and a 2.2 nF foil capacitor, a single jack socket and a pile of jumper wires.
What stands out is the teaching. Circuits are drawn by hand on dot-grid paper, and oscillation is explained through a water analogy: voltage as pressure, current as flow, resistors as narrow pipes, capacitors as balloons and diodes as one-way valves. Basic waveforms like square, triangle, sine, sawtooth, shark fin and reverse saw all get defined along the way. The prototype tracks volt per octave and produces proper synth tones when fed CV from a Korg SQ-1 step sequencer.
Not everything is settled yet. Sine wave generation is still an open problem on the research list, and the volt-per-octave conversion is deliberately saved for a later part of the series. That leaves room to grow, which for a part one feels about right.
Project by Moritz Klein. Watch it on their YouTube channel: