System X Oscillator DIY

Here’s the Roland 100M VCO adapted to Euro. The hard-to-find/easy-to fake ua726 diff pair has been replaced with a CA3046 with no loss of performance. No hard to find parts whatsoever. Panels are made by Ben at Re:synthesis.

The RANGE pot is a coarse tune (rather than the rotary of the 100M), and can take the VCO down waaaay low into LFO territory. The PITCH pot is fine tune.

Individual outputs for ramp, square and triangle – an improvement on the original.

I’ve spent a lot of time tweaking the levels of the waveforms relative to 0V to take into account Euro’s +/-12V supply (versus the 100M’s +/-15V supply).

I’ve also taken a lot of time to set it up so there should be absolute minimal tweaking of the trimmers for scaling etc. Really easy to set up without recourse to ‘scopes, frequency counters and precision reference oscillators! Accurate up to 7 octave too!

PCB and panel set for you DIY guys and gals:

SysO PCBpanel

One of my completed modules:

SysXO Front

PCB/panel build detail:

SysXO Back

Roland 100M VCO PCB: £15 GBP

Roland 100M VCO panel (10HP): £15 GBP

Build Documentation: System X Oscillator Build Doc

Each PCB now comes with additional tempco daughterboard for increased stability:


Daughterboard build document: System X VCO Tempco Build Doc

Schematic: System X Oscillator Schematic

For orders and queries please contact me at:

[email protected]