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Car RC systems -
how it all works

Just like everything else in the radio control world, car rc systems are advancing very quickly and are better value than ever before.


RC cars and trucks are almost always 2 channel - engine and steering, and with the exception of very simple mini rc models, a standard radio control set is fully proportional.

This means that the model responds directly to how much you move the controls on the transmitter.

In other words, if you move the throttle trigger only a bit, then the engine will only increase slightly; move it all the way and the engine will go to full throttle.
And the same with the steering control, if you just move it slightly then the model will only turn slightly.

Basically, having a fully proportional radio control set means that you always have complete control of your rc car or truck.


Transmitter (abbreviated to 'tx')

RC car transmitters can be either the pistol grip style or the traditional stick kind. The pistol grip is more common nowadays, but the stick transmitters are still used by many rc car drivers, as they do tend to offer more precise control of the model although it has to be said that the choice is purely down to personal preference.
Both styles of transmitter are shown below:


A typical pistol grip and stick rc car transmitter


The pistol grip transmitter is a great evolution; they're very comfortable to hold and offer great control of the model. The car or truck engine is controlled by the trigger, while the steering is controlled by rotating the wheel of the transmitter.

A pistol grip transmitter can be held in 2 ways, depending on whether you're right or left handed. Use your index finger on the trigger, and your index finger and thumb of the other hand to turn the wheel.
You may find that you're more comfortable with it one way than the other, regardless of whether you're right or left handed. It's really just a case of 'suck it and see'!


While right-handed pistol grip transmitters can and do accommodate many left-handed drivers, only one or two true left-handed pistol grip transmitters (with the wheel on the left side) are available, and this segment of the market still has significant room for improvement.
Some transmitters are also reversible, such as Futaba's 3PK range. (This info kindly submitted by Tom Eggert of Lombard, Illinois - thanks Tom!)


When using any radio control transmitter for an rc model, always use it with the antenna fully extended, or the model will very quickly go out of radio range and you'll lose control completely.


Receiver (abbreviated to 'rx')

A typical rc car reciever

In exactly the same way as a normal radio (or TV) receives a signal from the broadcasting station (for example, when you watch your favorite soap), a radio control receiver receives the signal that is sent out by the transmitter when any input is made by the operator.

The receiver is located within the model and is directly connected to the servos by small cables. A wire antenna extends from within the receiver to outside of the model, and should never be cut or looped up to reduce its length; by doing so, its ability to receive the signal from the transmitter is drastically reduced which can result in disastrous consequences by way of the model going out of range too early.

All radio control systems require a minimum length of antenna to operate successfully.


Servos

A typical rc car servo

A servo consists of a small but powerful electric motor and a set of plastic gears which are directly linked to the servo horn, located on the top of the servo body.
This horn is the 'hand' of the servo and links to the motor throttle control lever and the steering controls of the model.

One separate servo is needed for each of these controls, and connects to the motor/steering by a small wire linking rod.

When the signal from the transmitter is received by the receiver, it is then sent to the servo which responds by direct movement of the horn via the motor and gears.

Many types of servo are available depending on the usage required; they're available in different sizes and power but a 'standard' servo that will come as part of the radio control set will be fine for using in an rc car or truck.



Crystals

A set of rc crystals

Crystals determine which frequency the radio control set will operate on. For rc cars, a set number of channels have been designated, mainly around the 75mhz mark but also the 27mhz mark too. Both frequency bands also cover rc boats.

You can read about these frequencies in more detail here.

Both the receiver and the transmitter need their own crystal to operate correctly. It's always a good idea to carry at least one spare set of crystals with you so you can change channel at anytime if someone else is driving on yours.

When buying extra crystals, try and chose a range of widely spread channel numbers.


AA batteries are the most common for car rc systems

Batteries

The most common battery size for car rc systems is the AA 'torchlight' size.

Radio control sets don't consume batteries too quickly, but obviously with very regular use you need to be very aware of the power level of the batteries. A full day's action is usually enough to drain the overall battery level to a critical one.

For this reason, it's a good idea to buy rechargeable batteries if you can.
Nickel Cadmium (NiCd) batteries are the most commonly used in radio control gear although the newer Nickel Metal Hydride (Ni-MH) batteries with an even higher capacity and performance are now being favored.

Rechargeable batteries are quite a bit more expensive to buy than 'dry' (non-rechargeable) ones, but they soon pay for themselves.
Typical NiCd or NiMh batteries last for around 1000 charges, so that's alot of rc driving!

Always be aware of how much charge the batteries have, or if you're using dry cells then try and remember how much use they've had. Radio control transmitter battery meters, where used, are pretty accurate so you should be able to tell the state of the batteries from that.

If your transmitter doesn't have such a feature, it would be well worth investing in a small meter to read the voltage coming out of the batteries at any given time.
If the battery level is low, then your car will go out of range quickly and you'll lose complete control.


Red Rocket Hobby Shop hold a good selection of rc systems for cars, airplanes and boats.


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