There even exists LED specially taylored to the needs of doing duplex
operation.

- Henry


"Frithiof Andreas Jensen"
schrieb im Newsbeitrag ...

"Henry Kiefer" wrote in message
...

Do you know of other interesting devices or circuits good for misuse?

LED's work both ways, as a light emitter and a photodiode.

The inbuilt colour filter can be used to distinguish between Grass and Not
grass f.ex. by comparing output from a red and a green LED using white
light
as illumination.

Back when fiber was ex$$$pensive one often saw clever circuitry using two
transmitters to form a duplex connection over a single fiber.

The USD 10 solar powered garden lamps will, with a little persuation,
yield
a nice solar cell well below the price of a similar unit in the shops -
and - two 600 mAh NiMh batteries and a grotty circuit for switching the
LED.