[sdiy] Coarse and Fine Pots

[Roman Sowa]

You don't need 2 different values, just link the wipers to VCS's tuning 
input with 2 different resistors, like 100k and 500k.

Or use multiturn pot with rotation counter like in old oscilloscopes. 
Something like this for about $1:
aliexpress.com/item/1005006118062449.html

Roman


W dniu 2025-05-24 o 21:54, Terry Bowman via Synth-diy pisze:
> 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 <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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