Ghidirah VCOs

VCO Panel

Features

  • 1V/Octave Pitch CV
  • Initial Pitch
  • Scalable Exponental FM (Aux CV)
  • Scalable Linear FM
  • Scalable PWM
  • Initial PW
  • Sync In / Sync Out
  • Saw, Square, Triangle and Sine Waveforms

The 3 VCOs in Ghidirah are based on the excellent VCO designed by Ray Wilson.  The only real modifications made to the design was adding an additional input to the pulse width modulation so that I could have both scaleable PWM and initial PW for each VCO.  Pads were also added to the board so that I could pull +V and ground out for the panel controls.

VCO Block Diagram

Blue tags are input jacks, red tags are output jacks. The cyan circles are pots.  See the circuit diagram for their actual implementation.  The Exponential FM, Linear FM and PWM inputs use simple attenuators while the initial PW pot sweeps from +5 to -5.

Block Diagram