ajh-synth/minimod-vco
MiniMod VCO
A discrete-transistor voltage-controlled oscillator that faithfully recreates the rare early all-discrete RA Moog Model D oscillator, with four simultaneous waveform outputs (Sawtooth, Triangle, Square with PWM, and Sharktooth), switchable octave selection, exponential and linear CV modulation inputs, oscillator hard sync, and a Lo setting for sub-audio LFO use.1015
Capabilities 2
- LFOlfo
- With the Octave switch in the Lo position the VCO runs at sub-audio rates; frequency can still be varied via CV inputs, making it a VC-LFO.1015
- Voltage-Controlled Oscillatorvco
- Discrete transistor core emulating the early all-discrete RA Moog Model D oscillator; four simultaneous waveform outputs with 1V/Oct, Exp-CV, and Lin-CV inputs.1015
Jacks 9 (5 in / 4 out)
| Name | Signal | Voltage | Description |
|---|---|---|---|
| Inputs (5) | |||
| 1V/Oct | cv | — | Exponential 1V/octave pitch CV input; normalled to the distribution bus pitch line by default, overridden when a patch cable is inserted.1015 |
| Exp-CV | cv | — | Additional exponential frequency CV input; summed with 1V/Oct and Lin-CV for pitch control.1015 |
| Lin-CV | cv | — | Linear frequency CV input applied downstream of the exponential converter; useful for subtle modulation that remains more constant across octave changes.1015 |
| PWM CV | cv | -5V to 5V | CV input for pulse width modulation of the square wave; accepts ±5V; modulation depth set by the PWM CV attenuator knob on the front panel.1015 |
| Sync | audio | — | Hard sync input; expects a rising ramp waveform from the master oscillator. Falling-ramp sources should be inverted first. Threshold set by the sensitivity control.1015 |
| Outputs (4) | |||
| Sawtooth Out | audio | — | Rising ramp sawtooth wave output at Eurorack modular levels; available simultaneously with all other waveform outputs.1015 |
| Sharktooth Out | audio | — | The Moog-style asymmetric sharktooth waveform output, first introduced on the very early Model D VCO; available simultaneously with all other waveform outputs.1015 |
| Square Out | audio | — | Square wave output with fully adjustable pulse width modulation applied; available simultaneously with all other waveform outputs.1015 |
| Triangle Out | audio | — | Triangle wave output at Eurorack modular levels; available simultaneously with all other waveform outputs.1015 |
Parameters 5
| Name | Type | Range | Behavior |
|---|---|---|---|
| Octave | switch | — | Selects the octave range of the oscillator; includes a Lo position that sets the oscillator to run at sub-audio LFO rates, and normal audio-rate octave positions.1015 |
| PWM CV | knob | — | Attenuates the amount of external CV applied to the PWM CV input, controlling the depth of pulse width modulation from the CV source.1015 |
| PWM Width | knob | — | Sets the pulse width of the square wave output manually; position 0 gives a square wave, position 3 gives pulse 1, and position 5 gives the narrower pulse 2.1015 |
| Sync Sensitivity | knob | — | Sets the trigger threshold (sensitivity) for the hard sync input, determining the voltage level required to trigger oscillator reset.1015 |
| Tune | knob | — | Adjusts the overall pitch offset of the oscillator; used in conjunction with the Octave switch for frequency setting.1015 |
Firmware history 0 versions
No firmware history recorded.
References 1
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[1015]
AJH Synth MiniMod VCO product/manual pageproduct_page● verified 2026-05-28