Erica Synths SDIY Polivoks Eurorack VCO - Demo

store.synthrotek.com/Erica-Sy...
The core of the VCO is borrowed from the famous Russian synth Polivoks VCO and in exponential converter we use the original matched transistor IC that was used in Polivoks.
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
We have significantly updated schematics:
Introduced +-10V regulators for greater stability of operation,
Adjusted signal amplitudes to match requirements of contemporary modular synths and made all output signals available simultaneously,
Redesigned CV inputs to accept positive CV signals,
Introduced PWM circuit with manual and voltage controlled pulse width,
Introduced synchronization input, so you can sync the VCO to other VCOs.

[@greatlakestrader]

Really nice demo! Thank you! Erica Synths analog vcos have wonderful character!

[@synthrotek]

Thanks for taking a gander!

[@flourfree2K]

Impossible to replace UNKNOWN USSR CHIPS?
(Even impossible to READ, by the way!).
No, thanks.

[@ericMT]

Sometimes with DIY you have to find solutions to what appear to be difficult problems. In this case, you can replace the hard to source KR198NT1A with the more common AS3046 if needed for the matched transistor array.