Home > Radio Control - What is it?
Radio Control - What is it?
Basics of Radio Control*
A great number of people from around the world are enjoying the sport of Radio Control. Cars, tanks, motorboats, sailing ships and various aircraft are available in a R/C format. People find excitement in the precise mechanics and high performance of these models. Assembly, finishing, customizing and tuning, as well as organizing and participating in competition are only a few possibilities in the limitless hobby of radio control modeling. This is a guide compiled to focus on the fundamentals of electric powered R/C car models. * Before reading further, you might want to get familiar with the R/C terminology to better understand what you will be reading below. Visit our R/C Glossary
Radio Control System
When you buy a R/C car, a radio control system designated for the model should also be purchased. Most radio control systems on the market are of the digital proportional type. In short, they are called the radio. The system consists of a transmitter, a receiver and servo(s), plus power supplies for the units.
The Transmitter
An RC car transmitter serves as the control box. It allows you to maneuver the vehicle. Transmitters come in two different forms, the preferred pistol grip style and the 2-stick style. Most people who drive radio control cars prefer the pistol grip transmitters because they allow you to have more precise control of your car. You use the throttle trigger to give the car power and to brake and a wheel to steer much like a real car. To use the pistol grip transmitter, place your index finger on the throttle (trigger) and your index finger and thumb of the opposite hand on the wheel to steer. With the 2-stick style transmitters, you use both thumbs to control the car.
The Receiver
The receiver accepts the signals from the transmitter and converts them into pulses that operate the servo(s). The receiver is located on the car chassis and is connected to the servo by small wires. The signals received are sent to the servo, which converts the pulses into movements. This process of transmitting signals to the receiver and servo is called modulation.
The Servo
Servos convert the electrical impulses from the receiver into mechanical movements. *On a typical electric R/C, you only need one servo which operates the steering of the vehicle. While the older style mechanical speed controls require use of a second servo for the throttle, the newer electronics speed controls do away with the second servo. On a nitro vehicle, you will require two servos. One operates the throttle and brakes, and the other operates the steering.
The Number of Channels = The Number of Control Operations
The number of channels of the radio control system indicates the number of operations that can be controlled at a time. A four-channel digital proportional system will employ four servos to control four different types of functions. The radio controlled electric car is designed to be controlled in two ways, speed and steering control. Therefore, a two-channel radio control system is sufficient. Tamiya's more advanced vehicles, such as their Semi trucks and RC tanks, require a four channel radio.
About Radio Frequencies - Statutory bands for Radio Control
Radio waves are used very widely in society and are very important for medical emergency, police and the military. If these radio waves should be interfered with, obvious problems would develop. Therefore, specific frequency radio waves for different purposes are regulated and are handled by the FCC. Thus a number of frequency ranges are designated for model radio control and any other frequency ranges should not be used under any circumstances. (All info here on frequency, bands and crystals refer to use in the USA mandated, by the FCC)
Frequency Bands
This phrase "frequency band" stands for the frequencies of radio waves. The receiver will accept signals emitted even from another transmitter. If the frequency used is the same, the servos will also be put in motion. In other words, radio systems on the same frequency will respond to each other, thus causing them to go out of control. However, a number of radio control systems on different frequency bands can be used without interference. This is critical when operating among radio control groups and racing events.
The frequency of an R/C system is determined by the crystals used in the transmitter and receiver. Changing frequency crystals will alter the frequency band.
The frequency of an R/C system is determined by the crystals used in the transmitter and receiver. Changing frequency crystals will alter the frequency band.
*Limitations on Changing Frequency
Radio waves, used for hobby purposes, are classified into several frequency ranges. For R/C cars, there are two frequency bands, which are typically used, 27MHz and 75MHz. In order for your transmitter and receiver to operate correctly, they need to have their own crystals, which must match the frequency exactly. For example, you cannot change a 27MHz frequency crystal to a 75MHz range by using a 75MHz crystal. It is suggested to only use crystals from the same manufacture to prevent malfunctions. Also, it is good to have a spare set of crystals with you when driving with other people in case other drivers are using the same channel as you. *In the United States, 27MHz and 75MHz are the only frequency bands designated for R/C cars. No other frequency band should be used under any circumstance. There are 6 available channels on the 27MHz frequency and 30 available channels on 75MHz. 27MHz uses channels 1 through 6 and 75MHz uses channels 61 through 90.
*FM and AM Crystals are Different
There are two types of radio signals: AM (amplitude modulated) and FM (frequency modulated). Each uses its own exclusive frequency crystals and is therefore not interchangeable between AM and FM. Radio interference will still occur between AM and FM radios if on the same frequency. FM radios generally have clearer signal strength compared to AM, and by nature AM will carry a longer range.
2.4gHz Radio Systems
The latest form of radio technology uses a 2.4gHz radio signal rather than 27 or 75mHz. Rather than requiring each radio being used in a race to use a different crystal, the 2.4gHz radios have the ability to search for, and find any free channel on the 2.4gHz band, which virtually eliminates radio interference. A vehicle using 2.4 gHz will not turn on if it can not find an open channel.
Necessary Tools, Paints and Glue
Tamiya kits do not require many tools to assemble. In fact, some tools are included in Tamiya kits. Other necessary tools such as screwdrivers, pliers, side cutters, etc. are listed in your product manual.
Paints Cement Oil and Grease
Safety and Regulations and Operational Behavior
Radio controlled models can achieve speeds capable of causing serious accidents and personal injury should control be lost during operation. Therefore, all possible precautions should be made to avoid an accident including the following:
Do not use the streets to operate model cars.
Do not operate model cars near small children or in crowds.
When operating an R/C model, select an area where personal and/or property damage will not occur should the model crash.
Nitro engine R/C cars emit noise during operation and can be bothersome to others. Do not operate your model in an area where noise might disturb others.
To avoid radio interference and/or loss of control, inspect your transmitter, receiver, batteries (power supply) and model prior to operation.
Guidance for electric powered R/C car models
Of the many types of radio controlled models available, electric powered cars are the most popular. Entry-level kits are simple to construct and maintain. These cars are ideal for learning, while the high performance electric racing cars have the potential to satisfy the more experienced racer.
Types of Cars
Electric powered R/C cars are classified by the scale size of the model, such as 1/10th or 1/12th scale. 1/10th scale is currently the most popular sized electric powered cars. When categorized by the surface they run on, they are roughly divided into three groups: on-road, off-road and dual-purpose types such as rally cars and recreational vehicles.
Speed Controllers
Mechanical Speed Control Electronic Speed Control (ESC)
Motors
Brushless Motors Brushed Motors
Batteries
LiFe Batteries LiPo Batteries NiMH Batteries Ni-Cd Batteries
Compatible Ni-Cd Battery Charger Battery Safety
Disconnect and remove a battery from the model when not in use.
Do not dismantle or tamper with batteries or charger. Do not cut the battery cable, as it could short circuit and cause a fire or burns.
If a cable is worn, be sure to insulate any bare wires. Use heat shrink tubing or electrical tape for insulation.
Use only a compatible charger for recharging.
Cautions in Operating the Model
Do not attempt to run the model when its wheel movement is impeded. Avoid putting excessive load on the motor such as running through thick grass or heavy sand.
Nitro versus Electric
Revision: 102109