This is the Decade Sequencer PCB, a flexible step-sequencer built around the classic CD4017 Decade Counter. It transforms simple clock pulses into 10 sequential voltage outputs, letting you drive oscillators, LEDs, or any other circuit that reacts to voltage.

You can wire it for a full 10-step pattern or shorten it using a rotary switch or jumper, turning it into a 1-to-10-step sequencer for evolving rhythms and looping phrases. Each step produces its own voltage output, ready to trigger or modulate anything in your setup — from your Hex Oscillator or Quad Modulator, to external synth gear or logic toys.

Why I built it

After creating the Hex and Quad circuits, I wanted something to bring motion and order to the chaos — a circuit that would set the tempo and define musical patterns. The CD4017 was the perfect answer: a decade counter that turns logic pulses into rhythm and melody.

This PCB is fully hackable and educational, designed to show how digital logic can generate patterns, timing, and structure. Feed it a clock signal — from a Hex Oscillator, 555 timer, or any clock generator — and it instantly comes alive.

What makes it special

• 10 independent voltage outputs — one per step, ready to trigger, light, or modulate.

• Configurable step count — set sequence length (1–5 steps) via rotary switch or jumper.

• Flexible clock input — drive it from a Hex Oscillator, LFO, 555 timer, or external synth.

• Expandable & modular — chain multiple boards for longer or polyrhythmic sequences.

• Maker-friendly design — large pads, clear silkscreen, easy to mod and experiment with.

• Runs on 9 V DC — battery or bench supply.

• Educational value — perfect to learn counters, sequencing, and timing logic.

What you get

• 1 × Decade Sequencer PCB (silkscreen + drilled).

• PDF with schematic and BOM.

Who it’s for

• DIY synth builders and logic explorers.

• Students learning about counters and timing.

• Musicians seeking evolving rhythmic voltage patterns for modular or noise rigs.

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