> LEDs are really clever. The die is sealed with a lens of its own,
> on the chip, and the package is another lens.

JT> I've seen raw leds on a board, used for backlighting LCD
JT> displays. The leds in those things are exposed, that is, you
JT> could see and touch the wire that goes to the top of the led.

 Yair. The die has a lens of its own, included. The LED itself is
microscopic, like a point-source.

> What surpised me when I went right into it, was that an ordinary
> remote is so close to the ultimate range anyway. When I was
> testing Chinese TV, I used to complain if it went under 5 metres
> with fresh batteries, but if you try to get over 20m, you're
> really struggling. 

JT> Easy to take for granted, till you actually try to do it
JT> yourself.

JT> Dunno what environment (or range) Brenton needs.

> Outdoors... 20m. 

JT> Can it be focussed? Or is it a hand-held device that needs to
JT> be portable? 

 Both. It can be focussed, and battery-powered. Well-focussed LEDs
are readily available. I tried a bigger lens on the transmiter, but
the gain was negligible. The big gain with a lens comes on the
receiver.

Regards,
Bob
   

--- BQWK Alpha 0.5