This VCO is the fully configured version of the Compact VCO.

The core chosen is the well known Electronotes ENS-76 VCO Option 1 as used in the ASM-1, Modulus, etc. This core was an obvious choice due to the amount of information, lists of suitable substitutes and so on that are available on the web.

It has AC and DC linear CV inputs as well as 1V/Octave inputs and scalable/reversible CV inputs. It has sawtooth and pulse/square outputs, as well as a waveshape that is variable between sawtooth and a "sine-like" shape, and a fixed "sine-like" output too. It also includes a simple sub-oscillator for those who wish to experiment with that.

The [FINE] control is wired as a dual function control:-

• Between its mid-position (12 o'clock) to fully clockwise position (5 o'clock) the frequency range of the VCO is from around 8Hz to over 14kHz
• Between its mid-position and fully anti-clockwise (7 o'clock) the VCO can be driven down to LFO speeds as low as 1 cyle per 4 seconds

The sub-oscillator is based on that from an LM3900 application note (AN-72), but will not cover the full range available from the VCO core itself.

Note that the "sine-like" waveform is not a pure sine wave. There is a significant glitch in it that is almost impossible to trim out. As this is the recreation of a module that had such a waveshape, this is appropriate. If you require an accurate sine wave, this module is unsuitable for your purposes.