[sdiy] Coarse and Fine Pots

[Terry Bowman]

I'm upgrading my existing Oscilloscope Artist:

https://www.astarcloseup.com/2016/02/the-oscilloscope-artist.html <https://www.astarcloseup.com/2016/02/the-oscilloscope-artist.html>

I really need to add a fine tuning pot to two of the oscillators. I love the planetary mechanisms used for the VCO tuning on the Oberheim SEM but unfortunately they appear to be unobtainium right now. Are there any dual concentric pots with different resistances? It seems to me that a ratio of about 5:1 would be close to ideal so that would be 100kΩ/20kΩ. 

If not, can I just put a resistor in parallel with the fine pot? I know that the latter changes the curve and linear is preferable.

A related question: how does the sync to oscillator C work?


Terry Bowman, KA4HJH
"The Mac Doctor"

https://www.astarcloseup.com

#1: There is no substitute for good tools;

#2: Always use the right tool for the job.

Linn Westcott

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