There are two forms of remote control used for models: cable control and radio control.
Cable controlled models are not very common as they have range limitations (the range is determined by the length of the connection cable). An additional drawback is that much more power is needed for the extra load of the cable which has to be dragged by the model.
Models which are radio controlled are considerably more popular. They have very long ranges in which to operate, as the controlling unit is not attached to the model. Another benefit is that the control device itself can be very accurate in its control of the model's performance. The favourite types of radio controlled models are cars, boats and aircraft. The aircraft models are the most complex as they work in three dimensions.
Two types of radio control can be used, single channel (SC) and multi-channel. Single channel radio control can only govern one function, which is generally the steering. If a multi-channel unit is being employed then it can control a number of operations. If used for a radio controlled aircraft, the multi-channel can direct the ailerons, engine speed, brakes, undercarriage, elevator and the rudder.
The most basic single channel radio control model consists of a transmitter, a relay, a receiver and an electromechanical system.
When a button on the transmitter is pressed a constant signal frequency is produced, this travels to the receiver which amplifies the signal. The signal then actives a relay which operates the electromechanical system, and controls the desired function via lower power, highly precise, servometers.
