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A remote control is a device used for the remote operation of a machine.
Nikola Tesla developed one of the first examples of remote control. In
the United States patent
613809, named Method of and Apparatus for Controlling Mechanism of
Moving Vehicle or Vehicles (July 1, 1898),
he develops methods of and apparatus for controlling from a distance devices. In this patent, there is the first solutions for
controlling from a given point the operation of machines.
The term is most commonly used to refer to a remote control (usually just called "the remote") for televisions or other consumer
electronics such as VCRs, stereo systems, and
DVD players. Remote controls for these devices are usually small rectangular objects with
lots of buttons for adjusting various settings such as television
channel, track number, and volume. Most of these remotes communicate to their
respective devices via infrared signals and a few via radio signals. They are
usually powered by small (AA or AAA size) batteries.
Early remotes for televisions were mechanical and used sound to change the
channel and volume. When the user pushed a button on the remote control it clicked and struck a bar, hence the term "clicker".
Each bar emitted a different frequency and circuits in the television detected this sound.
The first electronic remote controls used sound because semiconductors
for emitting and receiving infrared radiation were either inadequate or too expensive. The controller contained a piezoelectric crystal that was fed by an oscillating electric current at a
frequency near or above the upper limit of human hearing (but still audible by
dogs). The receiver contained a microphone attached to a circuit that was tuned to the same
frequency. One drawback of this method was that the receiver could be easily triggered accidentally by naturally occurring
noises.
Remote controls exist for many other devices as well: model airplanes and helicopters are remotely controlled; many
robots are remotely controlled, especially those which are designed for doing perilous
tasks; and some state of the art military fighter jets are operated by remote control.
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