Our hope in sharing this information is to provide a very concise overview of how RC controls work for those who are just starting out, and would rather not piece it all together by watching a hundred YouTube videos.

An RC radio, otherwise known as a transmitter, is the hand held device where the user manipulates joy sticks ( gimbals) and switches to control the RC toy. Two of the more popular brands today are Radiomaster and FRSky. The radio communicates wirelessly with an RC receiver. The receiver is installed on the RC toy and translates the signals from the radio into output commands to control motors and servos. Most radios have two Gimbals with forward and back motion as well as left and right motion. Each of these motions represents a different input control, or channel. With most programmable radios you can configure in the firmware (software) which channel is mapped to which input. For example, the forward and backward motion of the right gimbal could be mapped to control channel 1 on the receiver. The communication between the radio and the receiver is called a Tx protocol (the T stands for transmitter), which refers to the language, or frequency that these device communicate on. Examples of TX protocols are ExpressLRS and TBS Crossfire. You must use a radio and receiver that have the same protocol in order for them to link and communicate.

RC radios are highly configurable. You can control a tremendous range of things through the firmware, such as causing the gimbals to control different channels by flipping a toggle switch on the radio. Switches on the radio can be mapped to other channels to control things that are not proportional, meaning they are only on or off controls, like turning on or off lights, or raising and lowering landing gear.

The RC receiver is the part that communicates wirelessly with the radio, and receives the wireless commands, and then sends out those commands through the various channels to control motors and servos. Receivers for RC land devices are usually a little different from those for flight devices. The receiver will have antenna wires for picking up the signals from the radio. The receiver will also have a place for receiving power from a voltage supply device like an BEC (battery elimination circuit). More about connections later. The receiver will also have pin connections that are for each of the channels. A receiver normally has a fixed number of output channels, like 4 or 8 for example. The communication between the receiver and the devices it will control is called an Rx protocol (the R stands for Receiver). Unlike Tx protocols, Rx protocols are wired, meaning physical wires connect the receiver to the devices it will control.

Receivers communicate with downstream devices using an Rx protocol. There are many of these protocols to choose from, but one of the most common is PWM, or pulse width modulation. Do not confuse this with pulse frequency. The receiver sends a pulse every so many milliseconds ( ms ) which is the frequency. It's the width of that pulse that determines the command the receiver is giving (See image below). With RC, the width of the signal pulse normally varies between 1000µs and 2000µs (micro seconds). So this range will determine the behavior of down stream devices. Motors and servos normally have a neutral position which is 1500µs pulse width for a stopped motor and for a non-continuous servo 1500µs would be center position. The minimum pulse of 1000µs width will cause motors to turn max speed in one direction, and the maximum pulse width of 2000µs will push them to maximum RPM in the other direction, normally. Although the behavior of all this can be highly configured by the radio. For example the throttle control on a plane propeller never needs to turn in reverse. So the radio can be set so one of the gimbals is at rest in the full back position and it applies power to the propeller motor all in one direction as the user pushes the gimbal through its full range of motion from back to forward.

An RC servo is basically a dc motor, but one that has the ability to control its position of rotation and stop at almost any position within its range of motion. Servos come in both analogue and digital, and they also come as either positional or continuous. A continuous servo will rotate like any other motor, but with more control over speed and the position it can stop at. A positional servo has a specific range of rotation such as 90, 180, or 360 degrees. Positional rotation servos will cycle to any position within their range of rotation, based on the input from the radio, or specifically the width of the pulses it is receiving from the receiver. Servos are connected to and control the flight surfaces such as ailerons, elevators, and rudders on RC planes. They also control steering on RC land based devices such as cars and crawlers.

Continuous rotation servos basically behave the same way as motors, described above. With positional servos, there is normally a neutral position configured for the servo, which would be the position it would return to if you take your hands off the gimbals or steering wheel. For example in an RC car, neutral would be set up such that at neutral position the front wheels of an RC car would track straight. Neutral would be represented by 1500µs pulse width. Moving the steering control on a radio to the maximum in one direction would output a pulse width of 1000µs and cause full servo actuation in one direction, and thus full steering turn in one direction. Moving the same radio control to the maximum opposite position would output 2000µs pulse width and cause the same maximum steering, but in the opposite direction. The output between neutral and full is proportional. So a steering control position 25% of the way from neutral to full would send pulse widths that move the servo 25% of it's rotation in one direction from neutral to full, and 50% on the steering control would do the same at 50% servo position and thus 50% of steering angle. This description is a bit over simplified but it's the most common scenario and conveys the concept correctly. All of this is highly configurable via the radio. You can set neutral to any position and adjust the range of motion through the firmware of your programmable radio.

An electronic speed controller is commonly called an ESC, and there are different kinds, namely brushed and brushless. A brushed ESC is for a brushed DC motor. I will spare you the explaination of brushed motors vs. brushless motors, you can google that. The connection between the esc and a brushed motor is 2 wires, + dc voltage and - or neutral. Thus a brushed motor only has 2 wires or connection points. The direction of rotation, clockwise vs counter clockwise, involves switching the + and the - voltage being sent to the two wires or connection points on the motor. Speed is determined by voltage from zero to the maximum allowed voltage for the given motor. And the speed controller ( ESC ) calculates what voltage to send to the motor based on the pulse width modulation, or width of the pulses being sent from the radio to the receiver. Brushless DC motors are more like a 3 phase motor, and use 3 wires to connect to the ESC. The brushless ESC controls both speed and direction of the motor by how it sends the voltage signals to the 3 connecting wires.

A flight controller sits between (electrically speaking) the RC receiver and the servos, esc's, or motors that are used in a flighing RC device. A flight controller is basically a small computer, and is the central component of a drone or UAV (unmanned aerial vehicle) that manages and stabilizes flight by interpreting onboard sensor data and commands coming from the RC receiver, and sending out commands to motors and other onboard systems. Flight controllers come in various types made for drones and fixed wing aircraft, including basic models with core stabilization functions and all-in-one versions with built-in features like GPS, barometers, and electronic speed controllers (ESCs). These all-in-one flight controllers simplify drone builds by integrating multiple functions into a single board. In contrast, modular flight controllers offer greater flexibility and customization, allowing users to attach external ESCs, GPS units, telemetry systems, and other components. Whether you're building a racing drone, a camera drone, or a fixed wing RC plane, selecting the right type of flight controller is essential for performance, reliability, and ease of setup.

LiPO batteries are popular for RC because they do a great job maintaining voltage over their discharge curve. A LiPO battery is a multi cell battery. Each cell contributes to the overall voltage of the pack. Below are some values worth knowing.

Peak Voltage 4.2 volts per cell, never charge above this. Minimum Voltage 3.0 volts per cell, going below this is risking damage. Safe Voltage is 3.3v per cell. Stop your RC device before the batteries are drained below safe voltage. Practical voltage is about 3.5v, and it's best if you don't run them below this. You will start to feel the power loss at this level. Voltage decreases under load and will rise again a little after the load is removed. Storage voltage 3.75 to 3.85 volts per cell is perfectly ok. Nominal Voltage is 3.7 per cell. This value is used for determining pack voltage.
Below are the nominal and peak voltages for 3, 4, 5, and 6 cell LiPO batteries.
3s 11.1/12.6
4s 14.8/16.8
5s 18.5/21.0
6. 22.2/25.2
Studies show that lowering your full charge voltage from 4.2 to 4.15 increased battery live cycles by 50 tp 100 percent. If you drop your full charge voltage to 4.1 you will increase the life by 100 to 200 percent.

Markings on the batteries:
450 mAh battery is 450 milliamp hours of stored energy, equates to how much work it can do. Discharge rate is normally listed as two numbers such as 30-40C. These values are continuous/burst values. So 450 mAh converted to amps is .450 amps. You take the amps times the discharge rate to find out what amperage the battery can deliver continuously and also can deliver in a burst for a short time. The battery pictured below only has one discharge rate listed, so .45 amps times 30, it can deliver 13.5 amps continuously. These values found on the batteries are often highly inflated. Only use balance charger for LiPO batteries. Some trickle chargers will charge through the balance wires but most charge using the main power wires to charge and they monitor/balance the voltage of each cell using the smaller balance wires. (balance wires are the white connectors below)