[sdiy] popping a cap into a VCO

[Jason Proctor]

why not ask roger? i hear he's a nice guy.



>I'm wondering if I can add a second cap to a Synthesizers.com oscillator.
>These VCOs have a "LOW" range, but I'd like to add an "ULTRA LOW" mode, if
>practical.
>
>The current cap is a 50V 0.01uF 'styrene. I know that I can (in theory) add
>a second cap in parallel with the first to increase the total capacitance
>and thus lower the frequency range of the VCO. I would use a switch to bring
>the cap in on demand. I'm considering a polyproylene cap as large as 1uF
>(100X the existing cap). I will not require ultra stability in ultra low
>mode, and styrene caps don't come so large as the polyprops.
>
>Will this scheme, in fact, work properly? (Leakage...?)
>
>More importantly, can the switch/wiring/etc. cause side effects, like tuning
>errors from stray capacitance? I don't know how sensitive VCOs are to such
>things, and of course I want it to play in tune in the non-LOW ranges.
>--
>john