>
> That is really rank, yes. Good application though.
>
> I suppose 'kicking the dog' would be inhumane as a trigger
> mechanism in this instance.
>
> I would suggest a simple one shot on the collar, and a little
> RF loop receiver, receiving from a simple transmitter sending
> a pulse every second. The pulse would re-start the ramping on
> the one shot and thus no change in the light output. When the
> pulse no longer comes, the collar shuts off.
>
> So two 555s, two transistors and some support circuitry,and you've got it.
> Very low range, perhaps a few meters, but should be good.
>
> Only problem you might have is if there are several blind people in
> the room, all the collars will stay activated if anyone is transmitting,
> but this is a minor problem that isn't worth the additional circuitry to
> solve.
>
> Craig
>
> >off after 1 minute with no reception? Might do! Whole new meaning to
> >"Watchdog Timer" though <Boo Hiss, I know.>)
> >
> > Mark,
mwillis
KILLspamnwlink.com
> >