very cool synth DIY eurorack modules from Finland!
The CEM3340 VCO chip is one of the legendary chips designed by Doug Curtis that played an important role in the analog polysynths of the 1980s. By integrating a complete analog VCO on a chip, it made more compact and cost-effective synth designs possible.
Together with the classic analog polysynths themselves, the Curtis chips have long been out of production. In 2018 however, thanks to the new boom in analog synthesis, the 3340 VCO chip is once again available, from no less than three sources. Curtis' own company OnChip Systems re-issued the CEM3340 Rev. G, and cloned/compatible devices are available from CoolAudio (v3340) and from the Latvian company Alfa (AS3340).
The Kassutronics VCO 3340 is designed to be a good balance between feature set and simplicity. It has good tracking and temperature stability, is easy to build with only through-hole components and easy to calibrate. In addition to the standard waveforms it has a sine wave output.