[sdiy] Mod Wheel Thoughts

[harrybissell]

The flat area, with a single cell... is a loser.   The cells have a really
poor thermal stability, so changes in temperature render the optical
flat useless.

You might do differential illumination on a center-tapped cell... at least the
two halves would track.

I think trying to null the center is too hard. I'm thinking "mod wheel = good"
"Pitch-wheel = bad"

H^) harry

john mahoney wrote:

> > Ian's thought about the stable initial position makes me think I need to
> > come up with some sort of
> > stable mechanical detente at the initial postion. I think I will combine
> > this with electronics that have a sort
> > of threshold. The circuit only responds after a minimum movement.
> > Making this unnoticeable will challenging.
>
> You could try an "optical detent" -- an area of 50% gray in the center
> section of the gradient. Here's an exaggerated (and poor quality!) version
> of what I mean:
> http://www.bitshifted.com/images/gradient.gif
>
> I am assuming that 50% gray yields a 50% CV output, though I don't know how
> linear the CDS response will be.
>
> A sliding shutter, cut at an angle, seems like a great way to avoid the need
> for a high quality gradient. Analogous to my optical gradient example, you
> could put a flat area in the middle of the shutter.
> --
> john