Trapezoid quadrature VCO through zero (flat version) with waveshapers

Trapezoid quadrature VCO through zero (flat version) with waveshapers
Trapezoid quadrature VCO through zero (flat version) with waveshapers: Front view

This is my second take on the Trapezoid VCO designed by Don Tillman. My first implementation can be found here. This time I mounted the PCB’s parallel to the front to save space and integrated the wave shapers. The core is still based on the original design from Don (used with permission). I found the original article and schematic about the Trapezoid VCO on Don Tillman’s site (Link to original article from 19 July 2003). The article consists off three parts with the core implementation in part 2. I kept the basic idea and changed nearly everything else. I use an other exponentiator scheme and temperature stabilization. Another reference voltage device is used. And quadrature square outputs are implemented. As well as the additional waveforms triangle, sine, ramp up, ramp down and pulse.

Specs and features

  • Trapezoid quadrature output
  • Square quadrature output
  • Triangle quadrature output
  • Sine quadrature output
  • Pulse output, 0deg, 90deg
  • Ramp up output 0deg, 90deg
  • Ramp down output 0deg, 90deg
  • Through zero modulation
  • PWM input
  • V/Oct, FM log and trough zero CV input
  • Temperature compensated
  • Coarse and fine frequency setting
  • Runs on +/-15V and +/-12V
  • Power consumption around 135mA each rail

The documentation and the Gerber files for download can be found in my website.

Trapezoid quadrature VCO through zero (flat version) with waveshapers: Back view
Trapezoid quadrature VCO through zero (flat version) with waveshapers: Back view