Advanced APC - 3-Oscillator Atari Punk Console Eurorack Module, 8HP Drone Synth, LFO, Chaos & CV Modulation, Circuit-Bent Punk Generator

User manual:

BIGZUN ADVANCED APC — 3-Oscillator Atari Punk Console | Eurorack Synth Voice | 8HP Part of the Timewind Project

Meet Advanced APC — a hand-built, three-oscillator Atari Punk Console for your Eurorack system. It's a digital adaptation of an analog module: inspired by the classic "Stepped Tone Generator" circuit made famous by APC noise toys, but rebuilt from the ground up on a stable digital core and pushed into genuinely chaotic, self-modulating territory. You get the raw, punchy, unpredictable character of classic 555-based noise circuits, plus full digital control over pitch, modulation and chaos depth — repeatable, tunable, and never drifting out of calibration.

NOT JUST THREE OSCILLATORS MIXED TOGETHER

Most "APC-style" modules simply run two square-wave oscillators in parallel and blend them. Advanced APC does something different — much closer to how the analog circuits that inspired it actually behave:

OSC1 is the master oscillator, always running freely.
OSC2 only runs while OSC1 is HIGH — exactly like the RESET pin of the second 555 timer in the original stepped-tone circuits that inspired this design. While OSC1 is LOW, OSC2 is silenced and reset.
OSC3 only runs while the already-gated OSC2 is HIGH, continuing the cascade.
And to close the loop: every rising edge of OSC3 hard-syncs OSC1, feeding back into the very first oscillator. The three voices constantly interact, gate, and re-trigger each other — producing a shifting, self-modulating rhythm that never quite repeats, rather than a clean, predictable cascade.

The result is that unmistakable "stepped," punky, slightly broken analog character — reimagined digitally.

MODULATION: LFO, CHAOS, OR EXTERNAL CV — YOUR CHOICE

Each of the three oscillators can be modulated in one of three mutually exclusive ways, switchable on the fly from the front panel:

LFO mode — each oscillator gets its own LFO, sweeping frequency around the pot's set position. Dial the overall modulation depth from 0–200% with TRANSPOSE UP/DOWN.
CHAOS mode — swap the periodic LFO for a free-running chaos generator. At randomized intervals, each oscillator either jumps instantly to a new random pitch (a sharp sample-and-hold "punch") or glides there at a randomly chosen speed. No two transitions are ever alike — perfect for generative, ever-evolving drones and noise textures.
CV IN — patch in an external CV or audio signal and it takes over modulation of all three oscillators directly, automatically overriding the internal LFO/Chaos engine. Great for syncing the module's chaos to the rest of your rack, or driving it from an envelope, sequencer, or another oscillator.

BLACK & WHITE OLED DISPLAY & MENU

A crisp black-and-white OLED screen shows live oscillator frequencies, gate states, active modulation source, and depth at a glance — no guessing what the module is doing. Press MENU to dive into a proper settings menu where you can fine-tune:

LFO MIN / MAX speed range (Hz)
CHAOS MIN / MAX retrigger interval (ms)
CV IN sensitivity (0–100%)
Factory reset
Firmware version (About screen)

All settings are saved automatically and remembered across power cycles.

INPUT & OUTPUTS

CV IN — the module's one input; patch in external CV or audio to take over modulation of all three oscillators
OSC1 OUT — dedicated output for Oscillator 1
OSC2 OUT — dedicated output for Oscillator 2
MIX OUT — the full mixed audio signal of all three oscillators

FRONT PANEL CONTROLS

Three frequency pots (OSC1/OSC2/OSC3), PLAY/STOP (LFO on/off), DIRECTION (POT ↔ CHAOS source), TRANSPOSE UP/DOWN (modulation depth), and a dedicated MENU/UP/DOWN cluster for settings — everything is one button-press away, no hidden shift functions.

SPECS

Format: Eurorack
Width: 8HP
Frequency range: approx. 20 Hz – 3 kHz per oscillator
Display: black & white OLED, real-time readout + settings menu
Power: standard Eurorack ±12V (check current draw in the included documentation before ordering if your case is tightly powered)

WHO IT'S FOR

If you're into noise, drone, generative patches, circuit-bending aesthetics, or just want a chaotic, characterful sound source that's genuinely different from another clean digital VCO, Advanced APC earns its spot in your case. It sits equally well as a stand-alone punk noise generator or as a wild modulation/audio source feeding the rest of your system through CV IN.

Every unit is built and tested by hand. Questions about firmware, compatibility, or build details? Just message me — happy to help before or after your purchase.