
T
he type of remote that you normally use to
control a TV, a Blu-ray player, or a surround-
sound system uses infrared light to send a
signal. It has the big advantage of being low cost,
but one obvious disadvantage: The gadgets that
you control must be able to “see” the remote in
your hand.
Remotes that transmit radio signals are much
more versatile. A common application is to open
a garage door when you approach it in your ...