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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 and 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; however, additional guidance on glow engine cars and sailing ships will be added soon. 

Radio Control System 
When you have bought a R/C model, 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 two servos, plus power supplies for the units. 

The Transmitter 
Your transmitter serves as the control box for R/C models. The standard transmitter uses control sticks, while a wheel and trigger type was developed for car models. When the transmitter is in operation, it emits signals by means of radio waves. 

The Receiver 
The receiver accepts the signals from the transmitter and converts them into pulses that operate the servo(s) installed into the model. 

The Servo 
Servos convert the electrical impulses from the receiver into mechanical movements. The servo motor then rotates and arm (servo horn) in a programmed direction. This movement then controls a specific model function; such as a car's steering or its speed. 

*Electric powered R/C models can use pulse width modulated electronic speed controls with integrated circuits. This eliminates a second servo and the mechanical speed control it would operate. Electronic speed controls are more efficient and require virtually no maintenance. 

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 basically designed to be controlled in two ways, speed control and steering control. Therefore, a two-channel radio control system is sufficient. 

About Radio Frequencies – Statutory bands for Radio Control 
Radio waves are used very widely in the 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 qualified personnel. Thus a number of frequency ranges are designated for model radio control and any other frequency ranges should not be used under any circumstances. 

Frequency Bands 

This phrase “frequency band” is used to denote the frequencies of radio waves. A receiver of the radio control system 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. 

Frequency Crystals 

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, the two bands are 27MHz and 75MHz and the frequency crystals are only interchangeable within each range. For example, you can not change a 27MHz frequency crystal to a 75MHz range by using a 75MHz crystal. In addition, replacing only the transmitter or receiver's crystal will result in loss of control over the model. Crystals in the transmitter and receiver must have the same frequency and should be produced by the same manufacturer. Spare crystals should be available from your R/C systems manufacturer. In the United States, 27MHz and 75Mhz are the only frequency bands designated for model car use. No other frequency band should be used under any circumstance. 

*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 are therefore not interchangeable between AM and FM. Radio interference will still occur between AM and FM radios if on the same frequency. 

Necessary Tools, Paints and Glue 
Tamiya kits do not require many tools to assemble. In fact, some tools are included in the Tamiya kits. Other necessary tools such as screwdrivers, pliers, side cutters, etc. are illustrated below. 

Paints 
Use plastic paints for styrene resins and polycarbonate paints for clear Lexan R/C car bodies. Spray type paints are convenient for finishing larger areas such as bodies. For painting details like figures, bottle paints for brush application are available. 

Cement 
The cement required will differ according to the model. If a special type is required, it will be indicated in the instructions. On a standard R/C car model, only instant CA cement (cyanoacrylate) will be required to secure rubber tires to the wheels. 

Oil and Grease 
It is necessary to lubricate gearboxes, shafts and bearings. Failure to lubricate these components will hinder rotation and movement, resulting in excessive wear and parts breakage. Some types of oil and grease will attack plastic. Therefore, select the type according to its intended use. 

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. 

*Glow 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 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. 

Radio Systems for R/C Cars 
The standard electric R/C car is controlled by a 2-channel, 2-servo radio consisting of a transmitter, receiver and two servos. The servos control the cars direction (steering) and its speed via a mechanical speed control. A mechanical speed control and its servo can be replaced with an electronic speed control. 

Mechanical Speed Control 
This system uses a resistor to impede the flow of electric current that governs the motors RPM. A 3-step mechanical speed control is used as an example here. At top speed, the resistor is bypassed and all the current goes to the motor. At low speed, the current flow to the motor is impeded by the resistor and bled off as heat. At mid speed, the amount bled off is about half of that at the low speed setting. The speed control servo moves a switch blade on the controller to vary the amount of electric current going to the motor. 

Electronic Speed Control 
The FET transistors in the electronic unit control the current going to the motor by interrupting the flow. The current and consequently the motors RPM, are controlled by the frequency of these interruptions. At top speed, no current interruptions take place. 

Motors 
Electric motors used in radio controlled vehicles are equipped with noise-suppressing condensers, to prevent radio interference. A 540 sized motor is often used in 1/10th scale model cars. Other sized motors are used depending on the scale or intended use of the model. 

*Specially wound, high performance motors for competition are available. These motors can be adjusted and tuned for specific use and their spare parts, such as rotors and brushes are available. 

Ni-Cd Batteries and Radio Control 
The most widely used power source for 1/10th scale R/C cars are the Nickel-Cadmium battery pack such as the 7.2V-2400mAh and the 7.2V-1700mAh battery. The packs consist of 6 in-line cells. The “7.2V” means the battery produces 7.2 volts of electricity and the “2400mAh” refers to the battery's capacity. A higher capacity means longer running time. For even more capacity, the 3000mAh Nickel-Hydride battery pack is also available. 

Compatible Ni-Cd Battery Charger 
There are two types of chargers available. An AC (alternating current) type which gets its power from an electric wall outlet and the DC (direct current) type which uses a vehicle battery as its source of power. Standard chargers take 4 to 8 hours to charge a Ni-Cd battery. Quick chargers are also available and shorten the charge time to 30 to 45 minutes. Always refer to your Ni-Cd / Ni-MH battery specifications when purchasing a compatible charger. Never attempt to charge a different type of battery. Use a Proper Ni-MH charger for the Ni-MH battery. 

Ni-Cd and Ni-MH Battery Cautions 
Large mAh capacity Ni-Cd and Ni-MH batteries provide enormous current, therefore, improper use or handling can cause serious accidents and injury. Always follow the instructions included with the battery, charger and model. 

*Disconnect and remove a battery from the model when not in use. 
*Do not dismantle or tamper with Ni-Cd and Ni-MH 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 
*The ceramic resistor of a mechanical speed control becomes very hot during use. If the car is run at low or mid speeds for extended periods, high levels of heat will develop. This could cause damage to the resistor or other vehicle components. 
*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.