Idea - X-4046 VCO for Fatman

[JovianPyx]

I had once tried to use a 4046 VCO on my Fatman and I never got it to work. I see the reason in the Thomas Henry X-4046 schematics found here.

I was looking at sheet-0001.pdf how the CV is turned into a current.

The schematic I've posted shows how I would connect the Fatman CV to this VCO and avoid the expo stuff.

Please note that this is 1) UNTESTED and 2) A very basic VCO.

Due to current chaos in my lab, I cannot yet try this, so if someone does and can confirm that it works and has a comparable range to the Fatman VCOs, please post.

Capacitor C is something you'll have to select. It might be from .001 uF to over .01 uF or more. The larger the cap, the lower the pitches it produces.

The output from pin 4 is square. If this works, it should be easy to add the Thomas Henry features to it.

Note that the 4046 is powered with Vdd=ground and Vss=-V. In the schmatic, -V is -12v and +V is +8v. Running this IC "below ground" is required in order to make the voltage to current converter work.

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Linear_4046_VCO.gif
Description:	Linear 4046 VCO Adapted for PAiA Fatman from Thomas Henry X-4046 Schematic
Filesize:	5.64 KB
Viewed:	10906 Time(s)

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[Cynosure]

Cool. Does this mean that you will soon be digging out the fatman and testing mods again?

[JovianPyx]