Radio Control Transmitters

Radio controlled models like cars, trucks, planes, and helicopters use what is called a radio transmitter. Transmitters are often abbreviated to simply 'Tx' by enthusiasts as a short form.

The transmitter is manipulated by the driver to increase and decrease the model's speed and to turn the vehicle. At its most basic form, the transmitter sends a signal to the model via a radio frequency, usually in the range of 27 MHz and 49 MHz. MHz is a common abbreviation for "Mega Hertz". "Hertz" refers to the periodic movement of a wave (cycles per second) and the "Mega" prefix means that the wave is moving at 10 million times per second.

Other more advanced RC models will sometimes use 72 MHz or 75 MHz frequencies. Usually these frequencies are used by remote controlled airplanes. The radio controlled car, truck, plane, or heli has a receiver built in to the model that can capture the signals sent to it by the transmitter. Most transmitters run off of common battery types such as 9 volt or AA alkaline (or rechargeable).

Fully proportional transmitters will enable the operator to have complete control of their vehicle. For example, depressing the trigger only slightly will make your vehicle move at a slow speed. Depressing the trigger on the transmitter so that it is in it's "fully open" position will enable you to control your vehicle at full throttle. The same can be said for the steering controls.

In years gone by, modellers used what was called a 2-stick type of transmitter. Some users still employ these; however, they are more commonly found on children's R/C toys rather than in hobbyist or professional use. The most common type of transmitter is the pistol grip style which incorporates a trigger for the throttle control and a wheel to adjust the vehicle's steering. There is no hard and fast rule as to how to hold your transmitter, however, most users find it convenient to use their left index finger on the trigger and their right hand on the wheel. Obviously, if you are left handed you may want to try holding it the other way around.

RC Receivers

As was mentioned earlier, you need both a transmitter (Tx) and a receiver (Rx) in order to control you R/C vehicle. The receiver is fitted inside the body of the vehicle, and is connected to what are called servos. The receiver sends the user's control signals to the servos which then tell the vehicle to accelerate, decelerate, or turn. This is called modulation and is usually based in the digital realm for current RC vehicles. The reciever is also connected to an external antenna which is able to interpret the radio frequencies that are emitted from the transmitter. Most receivers send out pulse-width modulation (PWM) signals to the servo, which then sends the signals to a motor that will control the vehicle's speed and turning ability.