The Dual VCO is a 4hp dual voltage controlled analog oscillator. Each VCO has square, triangle, and sine wave out, coarse and fine tuning controls, a control voltage input, and a switch for selecting between exponential or linear CV in. When a control voltage is inserted, the fine tune control becomes an attenuator for the incoming voltage. Each VCO runs from 5 seconds a cycle up to 18khz.
Note that there are two main quirks with this oscillator design: Below 300hz the waveform symmetry is slightly off. Triangle waves get a little uneven in the LFO range and the square wave turns slightly more trapezoidal above 1khz. Both VCO’s track 1 volt per octave almost perfectly – usually the 2nd and 4th octave will be a couple cents off. Other than these idiosyncrasies, this is a powerful and stable pair of analog VCO’s in a small footprint with no cross talk between the oscillators. It’s great for: drones and beating sine or triangle waves, cross modulating itself for interesting clocks/LFOs, creating complex waveforms/timbres through lin/exp frequency modulation.
Dual VCO Build Document – Assembly Guide
(pcbs come with smd matched transistors pre-soldered)
- Each VCO runs from 0.2 hz (5 seconds a cycle) up to 18k hz
- Very Stable, Temperature compensated circuit
- Waveform outputs: 10vpp
- Width: 4HP
- Depth: 45mm
- Current consumption: +12v 20mA, -12v 38mA