optical pots

[Ingo Debus]

Thomas Hudson wrote:
> The volume control on my car stereo is similar. If you turn it slowly,
> it probably takes four revolutions to go from full off to full on. If
> you turn it quickly it seems like a half revolution (or 3/4) is needed
> to cover a large portion of the range.

I don't like this kind of knob control (know it from the Ensoniq DP/4
for instance). Say, there's a parameter with a value range of 0 to 999
with steps of 1, and it's at 200 and you want to bring it to 300. So you
first turn the knob slowly: 201, 202, 203... turn it faster - ooops now
it's at 700... turn it back fast - now it's at 0.

I don't like mouse accelerators either.

This problem was cleverly solved on a old Hohner digital delay/reverb I
once had: 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. Turning became
harder then, so you could always "feel" whether you turned the "coarse"
or the "fine" pot. The delay time was controlled this way, it had a
range of 1 to 512 with steps of 1 and it was easy to set it to any
value.

Ingo