The coming of the computer and the exploration of space sparked the need for increasingly complex yet small, durable, and often remotely operated controls. This has brought about the age of microelectronics, which began in the 1950s centred around the transistor and silicon chip. It is a silicon chip that is the heart of the remote control that you see use to switch on your television set from the armchair.
When you press the button on the remote control, the chip which contains a microelectronics circuit sets off an electronic oscillator (vibrator). This produces an infrared beam, which is made up of electromagnetic waves.
The beam carries a coded signal, the code varying according to the button pressed to switch on, change channels, or raise volume, for example. The code based on binary digits is superimposed on the beam in the same way that a radio signal is superimposed on a carrier wave.
In the television set, the coded beam is received by a device sensitive to infrared waves. The incoming signals are amplified and fed to another silicon chip that identifies the code. The chip then feeds the appropriate signal to electronic switches that carries out your instruction.
Ultrasonic remote controls can be used to open or close the garage door. They emit high-frequency sound waves that are directed to receiving microphone. This send signals to an electric motor that operates the doors. However, the ultrasonic control must be operated in the direct line to the doors, so radio control is no more often used. A hand-held radio control is a miniature transmitter that can open garage doors fitted with a receiver from anywhere in the vicinity. The radio waves switch on an electric current to the motor that operates the doors.
A more complex radio control system is used to operate model aeroplanes and boats. The hand held transmitter sends out beams of coded radio waves. A miniature receiver on the model decodes the signals, separating them from the radio waves. The decoded signals are fed to tiny electric motors, called servos (short for servo-mechanisms, which increase their power). The servos open and close the engine throttle, raise and lower the landing gear, and operate the control surfaces such as ailerons and rudder – on the wings and tail.
Picture Credit : Google