Homebrew PCBs

> 
> Could you elaborate as to how..... Especially in a
> power down condition where upon one could loose track.
> I take it, there is some trick, as many devices, use
> relative rather than absolute positioning. WIthout a
> home position to index off of, it would seem one could
> loose the position of the pointer if it were turned
> and power was off.... Or is it interrupt driven such
> that the micro stays alive and wakes up should the
> shaft be turned???
> 
> Ron

Maybe do like was already stated earlier and just use LEDs around the 
dial to indicate position.  Then don't put any position indicators on 
the dial itself.  Then when you turn the unit on, you could have it 
start in the "home" position no matter how much the dial itself has 
moved while off.


Or you could use a bunch of reed switches mounted in a circle and a 
magnet mounted to a disc on the shaft, but I'm sure that would be 
pretty pricy.

I've heard that green LEDs can act as photodetectors.  They are cheap 
if you could get them to work.  Then just put a bunch in a circle a 
detectors and one on a disc on the shaft as an emitter.  Anybody have 
any luck using LEDs as detectors?

Ben Englund