optical pots

[Phillip L. Harbison]

debus at cityweb.de wrote:
> [...] there was a "coarse" and a "fine" pot both operated with one
> knob: normally turning of the knob just turned the "fine" pot, but
> when one end was reached, the "coarse" pot was turned instead. [...]

I've always heard these called vernier pots.  You'll also find them
in the trigger controls of old Tektronix scopes (e.g. Tek 465).
Real vernier pots are expensive but you could fake the behavior
using a cheap rotary encoder and some means of indicating whether
you're in course or fine mode (maybe a fine LED).


--
*name: Phil Harbison
*path: alvitar at xavax.com
*URL: http://www.xavax.com/alvitar