Erica Synths DIY Polivoks VCO ii

Erica Synths DIY Polivoks VCO ii

Erica Synths DIY Polivoks VCO ii

Erica Synths released this design for open source in 2020. 

The core of the VCO is borrowed from famous Russian synth Polivoks VCO and in exponential converter we use the original matched transistor IC that was used in Polivoks.

 But we significantly updated schematics:

1) we introduced +-10V regulators for greater stability of operation,

2) we adjusted signal amplitudes to match requirements of contemporary modular synths and made all output signals available simultaneously,

3) we redesigned CV inputs to accept positive CV signals,

4) we introduced PWM circuit with manual and  voltage controlled pulse width,

5) we introduced synchronization input, so you can sync the VCO to other VCOs.

     Features:

• Triangle, saw and pulse wave outputs
• Manually adjustable and CV controlled pulse width
• Great tracking across 8 octaves
• Exponential FM input with attenuator
• Synchronization input
• Octave switch – 5 octaves
• Skiff-friendly design