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DIY Stompboxes => Building your own stompbox => Topic started by: anyuser00 on February 24, 2004, 07:02:45 PM

Title: Variable Capacitor?
Post by: anyuser00 on February 24, 2004, 07:02:45 PM
Is there any way to get a variable non-mechanical Capacitor.  I mean is there something like a LDR for capacitors?
Title: Variable Capacitor?
Post by: Tim Escobedo on February 24, 2004, 07:07:07 PM
There are varactor diodes. But they tend to be useful for rather small capacitances.
Title: Variable Capacitor?
Post by: Brian Marshall on February 24, 2004, 08:55:49 PM
i've never tried them, but there are switching caps....   i dont know much about them, except that they exist, and i believ require some external components to control
Title: Variable Capacitor?
Post by: ExpAnonColin on February 24, 2004, 09:32:54 PM
You know, you can probably get the same effect with variable resistance.  You can get a somewhat similiar or very much comprable effect by basically making a LDR pot between 2 capacitors.  What you do is make one LED driven by some waveform, the other by an inverted form of the same waveform, and then 2 photcells of near exact values for each.  You then wire the "middle" to a junction of the 2 photocells and then either side of either photocell to the 2 "top" and "bottom" capacitor values you want it to go up and down to.  This would work better in a tremolo/LFO sort of setting than an envelope setting.

-Colin
Title: Variable Capacitor?
Post by: anyuser00 on February 24, 2004, 10:46:38 PM
Thanks guys, this is actually for a tube fuzz wah.  http://www.ax84.com/fuzzwah.html
(http://www.muzickicentar.co.yu/sheme/effects/wahsweel/SvetlanaFuzzWahTube.gif)
I am building an amp and have a few extra tubes I can use, so I want to integrate this within my amp and control it from an external pedal.

:)