Buzz
Playing with rc-cars is timeless fun Hill Street Studios / Getty ImagesSaturday morning TV ads often hype the incredible features of RC cars like the "Super Ultra Road-rippin' Devastator." You might also spot enthusiasts at parks piloting model airplanes, blimps, or small boats gliding across water.
This article dives into the world of radio control, explaining the frequencies used, the key components, and how they function together. Additionally, it clarifies the distinction between radio control and remote control in the context of toys and models.
Varieties of RC Toys
RC toys are available in a wide range of models, such as:
- Cars
- Trucks
- Fantasy vehicles
- Airplanes
- Helicopters
- Blimps
- Sailboats
- Motor boats
- Submarines
- Robots
- Animals
Although the operational mechanics vary across different RC toys, the foundational concept remains consistent. Every radio-controlled toy consists of four primary components:
- Transmitter - Held in your hands, the transmitter sends Radio waves to the receiver, allowing you to control the toy.
- Receiver - Located inside the toy, the receiver, equipped with an antenna and circuit board, picks up signals from the transmitter and directs the toy's motors accordingly.
- Motor(s) - These Motors drive wheels, steer the vehicle, power propellers, and more.
- Power source
The transmitter communicates with the receiver via radio waves (refer to How Radio Works for more information), prompting the motor to perform a specific function. For instance, in a car, the motor turns the wheels, while in a plane, it adjusts the flaps. The power source is usually a rechargeable battery pack, though standard batteries are sometimes used.
In numerous RC toys, the radio-controlled motor handles steering, while a separate power source drives the movement. Here are a few examples:
- Model airplanes often rely on a small gas-powered engine to spin the propeller, with the RC motor managing the flaps.
- Sailboats harness the wind for forward motion, while the RC motor operates the rudder.
- Blimps use helium or hot air for lift, with RC motors controlling small propellers.
Now, let’s examine each of the primary components in greater detail.
Head over to Consumer Guide to discover a wide range of RC options, including cars, boats, hovercrafts, tanks, planes, helicopters, and even insects. Alternatively, you can build your own using a radio-controlled toy kit.
RC Toy Transmitter
A standard transmitter for RC carsMost RC toys come with a compact handheld device featuring controls and a radio transmitter. This transmitter communicates with the toy’s receiver via a specific frequency. Powered by a 9-volt battery, the transmitter supplies energy for both the controls and signal transmission. Unlike remote-controlled toys, which use a physical wire, radio-controlled toys operate entirely wirelessly.
The majority of RC toys function on either 27 MHz or 49 MHz, frequencies designated by the FCC for consumer products like garage door openers, walkie-talkies, and RC toys. More advanced RC models, such as high-end RC airplanes, often use 72-MHz or 75-MHz frequencies.
Most RC toys display their operating frequency on a label. For instance, the RC truck shown below is marked as a 27-MHz model.
This truck is designed to function at 27 MHz.Many RC toy producers create versions of each model for both 27 MHz and 49 MHz frequencies. This allows users to operate two identical models simultaneously, ideal for racing or group play, without interference between transmitters. Some brands, like Nikko of America, even offer detailed information about the specific segment of the frequency band their toys use. For instance, they provide racing sets of up to six toys, each tuned to a distinct part of the 27-MHz range.
Transmitters vary from basic single-function controllers to advanced models with multiple features. A single-function controller, for example, might only move the toy forward when the trigger is pressed and backward when released, requiring the toy to be turned off to stop.
Most full-function controllers come equipped with six controls:
- Forward
- Reverse
- Forward and Left
- Forward and Right
- Reverse and Left
- Reverse and Right
In most full-function controllers, the toy will stop and wait for commands when no buttons are pressed or knobs are turned. Advanced RC systems often feature dual joysticks with multiple sensitivity levels for accurate maneuvering.
Radio Control
A standard RC signal transmission processLet’s examine the RC truck from the previous page in more detail. Assuming it operates at 27.9 MHz, here’s what happens when you use the RC transmitter:
- Pressing the trigger sends the truck forward.
- The trigger connects two electrical contacts, completing a circuit linked to a specific pin on an integrated circuit (IC).
- This triggers the transmitter to send a series of electrical pulses (see How Radio Works for more details). Each sequence includes a brief synchronization pulse group followed by the main pulse sequence. For this truck, the synchronization segment—alerting the receiver to incoming data—consists of four pulses, each 2.1 milliseconds long, spaced 700 microseconds apart. The pulse segment, which conveys new information, uses 700-microsecond pulses with 700-microsecond intervals.
A standard RC signal transmission processpulse sequences
- Forward: 16 pulses
- Reverse: 40 pulses
- Forward/Left: 28 pulses
- Forward/Right: 34 pulses
- Reverse/Left: 52 pulses
- Reverse/Right: 46 pulses
- The transmitter emits bursts of radio waves oscillating at 27,900,000 cycles per second (27.9 MHz). As explained in How Radio Works, this is known as pulse modulation.
- The truck continuously scans the designated frequency (27.9 MHz) for signals. Upon receiving the radio bursts, the receiver filters out all frequencies except 27.9 MHz, converting the remaining signal back into an electrical pulse sequence.
- The pulse sequence is decoded by the truck’s IC, which activates the corresponding motor. For example, a 16-pulse sequence (forward) prompts the IC to send positive current to the wheel motor. A 40-pulse sequence (reverse) would reverse the current, spinning the motor in the opposite direction.
- The motor’s shaft is fitted with a gear instead of being directly connected to the axle. This reduces speed but increases torque, allowing the truck to operate efficiently with a small electric motor.
- The truck moves forward.
Inside the RC truck, you’ll find a surprisingly straightforward design.
Inside an RC Truck
A glimpse inside the truckInside the RC truck, you’ll find two electric motors, an antenna, a battery pack, and a circuit board.
One motor controls the front wheels for steering, while the other drives the rear wheels for forward or backward motion. The circuit board houses the IC chip, amplifier, and radio receiver. Simple gears link the motors to the wheels, showcasing the impressive range of movement achieved with minimal components.
- The car’s interior features a circuit board equipped with capacitors, resistors, diodes, and the IC that manages the motors. The radio receiver includes a crystal oscillating at a specific frequency, inductors, and an antenna.
- The motors are powered by the batteries, with the IC regulating the power flow.
