This is the Quad Modulator PCB, a creative sound circuit based on the legendary CD4093 NAND Gate chip. It contains four logic-based oscillators that can modulate each other in endless ways — amplitude, frequency, rhythm, or pure chaotic noise.

Pair it with any signal source (like your Hex Oscillator, or other synth toys), and you’ll instantly open a world of evolving tones, glitches, and mechanical textures. You can also use it standalone — patch a few jumper wires between its sections, and it becomes a self-modulating sound creature that never stops morphing.

A bit of story

After I built my first Hex Oscillator, I wanted something that could breathe life into it — something that would turn its steady tones into living motion. That’s how the Quad Modulator was born: a compact logic playground where oscillators feed, fight, and reshape one another.

It’s a circuit for explorers — musicians, synth builders, and curious minds who love discovering how simple logic gates can produce complex, organic behavior.

What makes it special

• Four logic-based oscillators — each one can act as carrier or modulator.

• Patchable architecture — connect them in any combination using jumper wires.

• Cross-modulation magic — create complex amplitude or frequency modulation patterns.

• Standalone or companion — works beautifully with the Hex Oscillator, filters, or any DIY sound circuit.

• Rugged design — through-hole components, forgiving layout, and protected power rails.

• Simple 9 V operation — runs from battery or DC supply.

• Educational — perfect to demonstrate modulation principles, feedback, and logic-based synthesis.

What you get

• 1 × Quad Modulator PCB (silkscreen + drilled).

• PDF including schematic and BOM.

Who it’s for

• DIY synth makers, circuit benders, and sound designers.

• Students learning how modulation works.

• Experimental musicians looking for unpredictable, evolving textures.

Collect all 6 modules to create your own Audio Sequencer with modulation!