Pip LFO

ALM Busy Circuits 4HP
LFO VCO

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Compact analog LFO with square, saw, triangle, and sine outputs, each available in bipolar and unipolar versions. VCO mode enables audio-rate 1V/oct tracking over ~5 octaves.

Patch Ideas · 3

Clocked reset
Clock → Rst · LFO rate slower than clock for rhythmic waveshaping
Walkthrough
  1. Leave Pip LFO in LFO mode (VCO LED off).
  2. Set Freq knob slower than your clock — e.g. knob around 8–9 o'clock for a multi-beat cycle.
  3. Patch Clock Out → Pip LFO Rst input.
  4. Patch Pip LFO Triangle (bipolar) → VCF Cutoff CV.
  5. Send audio through the VCF so you can hear the sweep being retriggered on each clock edge.
Signal out Pip LFO Triangle (bipolar) — ±5V triangle, but restarted from zero on every clock pulse so the waveform becomes rhythmic chunks instead of a free ramp.
Listen for The filter sweep locks to the clock. Instead of a smooth drift, each beat kicks the triangle back to the start, producing a stuttering, rhythmic waveshape — tempo-synced modulation from a free-running LFO.
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: PIP LFO, Clock, VCF. Signals: 1 cv, 1 trigger.PIP LFOClockVCFMode: LFOFreq: slower than clockRsttrigTriangle bipolarcvOuttrigCutoff CVcv11. resets cycle rhythmicallycvtrigger
VCO with multiple waveforms
V/Oct → Freq · bipolar saw → VCF · unipolar tri → VCA CV
Walkthrough
  1. Press the VCO button so the LED lights (audio-rate mode, 1V/oct tracking over ~5 octaves).
  2. Patch Sequencer V/Oct Out → Pip LFO Freq (CV) input.
  3. Patch Pip LFO Saw (bipolar) → VCF Audio In (this is now your oscillator tone).
  4. Patch Pip LFO Triangle (unipolar) → VCA CV — the triangle doubles as a pitched envelope-like mod source.
  5. Route VCF → VCA → Mixer.
  6. Optional: send a trigger into Rst for hard-sync accents on each note.
  7. If tracking drifts across octaves, calibrate the rear V/OCT TRIM screw (1V and 3V, tune to same note two octaves apart).
Signal out Pip LFO Saw (bipolar) — ±5V audio-rate sawtooth at the sequencer's pitch. Pip LFO Triangle (unipolar) — 0–5V triangle at the same audio rate, used as a pitched VCA CV.
Listen for A raw analog sawtooth voice tracking the sequencer. The VCA gain warbles at the same audio rate as the pitch (the unipolar triangle), giving the tone a buzzing, ring-mod-flavoured amplitude character that follows pitch.
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: PIP LFO, Sequencer, VCF, VCA. Signals: 1 audio, 1 cv, 1 pitch.PIP LFOSequencerVCFVCAMode: VCOFreq CV1v/octSaw bipolaraudioTriangle unipolarcvCV1v/octInaudioCVcv11. 1V/oct trackingaudiocvpitch
Unipolar modulation
0–5V sine → filter cutoff for upward-only modulation sweep
Walkthrough
  1. Leave Pip LFO in LFO mode.
  2. Set Freq knob to taste — around 9 o'clock for a slow filter breath.
  3. Patch Pip LFO Sine (unipolar) → VCF Cutoff CV.
  4. Set the VCF cutoff manually to where you want the lowest point of the sweep (the sine rests at 0V).
  5. Send audio through the VCF.
Signal out Pip LFO Sine (unipolar) — 0–5V sine that only rises above the resting cutoff, never below.
Listen for A one-sided filter sweep: the cutoff opens upward on each cycle and returns to your set point, instead of dipping below it. Useful when you want modulation to add brightness without ever darkening the sound.
▸ Show diagram
Patch diagramPatch diagram with 2 modules and 1 connection. Modules: PIP LFO, VCF. Signals: 1 cv.PIP LFOVCFMode: LFOSine unipolarcvCutoff CVcv11. 0-5V sweep opens filter only upwardcv

Behaviors

LFO Mode default

Free-running LFO from ~0.01Hz to 30Hz. All waveform outputs available simultaneously in bipolar and unipolar versions.

VCO Mode VCO button press

Audio-rate oscillator tracking 1V/oct over approx 5 octaves into ultrasonic range. LED lit. Rear trimmer for calibration.

Hard Sync trigger → Rst

In VCO mode, a trigger to Rst resets the waveform cycle for hard sync effects.

Controls

global Freq Sets LFO frequency. Also acts as additional CV input.
~0.01Hz (90s) to 30Hz in LFO mode · extends to ultrasonic in VCO mode
global VCO Mode Button Toggles between LFO and VCO (audio rate, 1V/oct) mode.
LED indicates VCO mode active · V/OCT TRIM on rear for calibration

I/O

IN · 2

  • Freq (CV) 1V/oct in VCO mode CV
    Voltage control of frequency, summed with Freq knob.
  • Rst trigger GATE
    Trigger input resets all waveform cycles. Hard sync in VCO mode.

OUT · 7

  • Square 0–8V
    Unipolar square wave output only.
  • Saw (bipolar) ±5V
    Bipolar sawtooth output.
  • Saw (unipolar) 0–5V
    Unipolar sawtooth output.
  • Triangle (bipolar) ±5V
    Bipolar triangle output.
  • Triangle (unipolar) 0–5V
    Unipolar triangle output.
  • Sine (bipolar) ±5V
    Bipolar sine output.
  • Sine (unipolar) 0–5V
    Unipolar sine output.