via Neil Johnson on the SDIY list: "I've just finished characterizing my latest module - a dual sine VCLFO based on an SSM2164. One VCLFO produces three sinewave outputs, 120 degrees apart, over a range of around 100Hz down to 12 minutes, and a second auxiliary VCLFO with a diode-shaped single sine output from 300Hz down to around 7 minutes.By changing the capacitors this could also comfortably work in the audio range, but there is no temp.compensation so I wouldn't recommend it for stable VCO usage. Alternatively, a couple of component changes and this will go down to an hour or more per cycle."
You can find samples and more modules at Neil's Webbly World.
PCBs are available.
Specs on the Voltage Controlled Dual Sine Very Low Frequency Oscillator
" * Main oscillator
o 3 high-purity sine waves
o 120 degees apart - 0°, 120°, 240°
o 12 minutes per cycle up to 170Hz
* Auxiliary oscillator
o Single sinewave output (diode-shaped triangle) - triangle available via component substitution.
o 7 minutes per cycle up to 300Hz
* 100k input impedance
* short-circuit protected output buffers
* output levels ±5V
* operates from regulated ±15V supplies through 0.156" (3.96mm) 4-pin header (compatible with MOTM, Oakley)
* signal pads suitable for HE14 industrial connectors, dual-row 0.1" headers, or direct wire connection
* high quality fibreglass PCB, through-hole plated, soldermask, silkscreen legend, with full ground plane
* 80mm x 80mm (3.15" x 3.15") PCB with 70mm x 70mm (2.75" x 2.75") fixing centres"
