ZOE - Simple Saw VCO

This is a simple saw-wave generator VCO that features 1/v per octave functionality. This inital version is almost an exact rip-off of this VCO https://www.youtube.com/watch?v=rq4ovZ2om6k, which itself is a modified version of Ray Wilson's VCO: https://www.soundtronics.co.uk/Datasheets/7210-001-VCO.pdf. The 2nd version is based off the saw-wave oscillator base of Jim Patchel's VCO (http://www.noniandjim.com/Jim/synthmodulesII/200-1007.pdf), with some modifications to remove obsolete or difficult to source parts.

Revision List

Rev 1.0 - March 2021

• Exact copy of the VCO by vk2seb on youtube

Rev 1.1 - April 2021

• Started redrawing the schematic based on internal EAGLE blocks with multi-part compnents rather than the blocks from libraries.
• Never finished

Rev 2.0 - December 2021

• Redrew the VCO based on Jim Patchel's design, which is very similar but:
• Uses an MAT04 (I use a MAT14 instead), as opposed to a LM3046. Both are obsolete but a replacement for the MAT04 is available.
• Heat/Temperature compensation via LM13700 OTAs which feed the linear to exponential converter (much better performance expected)
• Oscillator is based around an N-channel JFET instead of several BJTs and op-amps (better performance expected).
• Elimination of several components due to simplification of the overall design

Rev 2.1 - December 2024

• Board now conforms to the ZOE standard (as it is at the end of 2024)
• Board and Schematic drawn in KiCAD
• Standardized labels on all the components
• PDF of the schematic
• List of Materials

TODO list/future features:

For a more complete list, please see the projects page

• Documentation on how the oscillator actually works.
• Move all the potentiometers onto a daughter board (stackable?) for a cleaner and more professional user interface