Bill,

On Tue, 7 Feb 2006 20:24:53 -0800, William "Chops" Westfield wrote:

> On Feb 7, 2006, at 1:17 PM, Peter wrote:
> 
> >> But really, a circuit like that hooked up to
> >> a serial port with the clock derived from a one-shot...
> >
> > How about two phototransistors suction cupped to the monitor
> > screen and a program to flash two rectangles in the right seuqence ?
> 
> I had a remarkably similar thought myself, although I was going
> to use CDS photocells...  We're all sick.

I think CdS cells would be too slow - you really need semiconductor detectors to make it feasible.
 
> Maybe we should just do it?  It probably takes at least 3 signals,
> doesn't it?

Two should be enough: Clock and Data.  The device would need to train itself to the light and dark levels each 
time it was used, but that shouldn't be difficult.

Timex made a watch a number of years ago that used this technique, so that you could maintain a diary (and 
perhaps address book?) on the PC and transfer your appointments to the watch so it could act as an alarm clock 
for anything you had booked.  Quite clever, but you'd use Bluetooth nowadays for the same thing, and it tends 
to be phones rather than watches.

Cheers,


Howard Winter
St.Albans, England


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