Picture of The Complete Guide to RC Electronics
Hello, my friends.

I have often found hobby RC electronics to be of interest in my projects due to their apparent simplicity and ease of use. However, it took me a while to figure out how to put together all the different components, figure out where to get all of the stuff, and read all of the (rather peculiar) ratings when I was trying to build something. Therefore, I hope that this guide will speed things up for you and lead to successful projects.

Quick reference:
1 - Where to obtain parts
2 - Transmitter
3 - Reciever
4 - Servos
5 - Motor controllers
6 - Motors, Propellers and Gears
7 - Batteries
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Step 1: Where To Procure Components

Picture of Where To Procure Components
After much research, i have found the following to be reliable, have a reasonable price, and have good selection:
 - Hobbyking: A Chinese-based distributor with a huge selection of motors, controllers, and everything else. mostly flying things. Shipping takes forever.
 - Horizon Hobby: Based in the USA, also have a large selection of items, but mostly ground-based vehicles.

There are other, cheaper websites, (like GoodLuckBuy) however I have heard that the reliability and customer service of these is often compromised.

Step 2: Transmitter

Also often abbreviated as Tx, this is the thing that actually takes your commands and sends your receiver the commands for the servos and the motors.

There are many Transmitters available on the market nowadays, and the low-cost ones start around $30. However, remotes for RC airplane or helicopter pilots, with programmable features, model memory, and computer simulators can start around $150 and go to nearly $3000.

All RC Remotes have a certain frequency that they operate on. Older, analog remotes operate on lower frequencies, which were determined by a crystal. Modern, digital, remotes usually operate in the Gigahertz Range, often at 2.4GHZ.

RC airplane and helicopter remotes have control sticks, which are mostly self explanatory. Usually, one of the two control sticks on an airplane remote is the throttle control stick, and is not spring loaded in the vertical direction, which means it will not spring back when you let go. Remotes are usually available with this stick on either the left or the right side, and are sold as mode 1 or mode 2. RC car remotes have a trigger and a knob to control different things.

Most RC remotes have something next to the Control sticks called the trim. this basically slightly alters the position of your control sticks, and is useful for finely altering the position of the servos, or the starting point of a motor controller. Transmitters also often have reversing, which reverses the output signal of the control sticks. this is usually controlled by a series of switches at the bottom of the transmitter.

The number of channels a remote has shows how many things it can control. For example a three channel remote could control three things, such as three servos, three motors, or a combination of any of those. Motor controllers and servos receive the same type of signal.

Expo, Telemetry, Limited travel and Model memory are all things seen on better, more expensive transmitters, but are not necessary for the average project. Expo stands for exponential rates, so that linear movement of your control sticks will result in an exponential output signal curve. Telemetry transmits information from the vehicle (such as battery voltage, altitude, motor temperature, etc.) back to the transmitter and displays these on the transmitter. Limited travel means that by moving your control sticks to their maximum will only send out a 30% signal, or whatever you set it to. both of these features are beneficial to sensitive mechanisms and airplanes, so that one can maintain better control over them. Model memory simply allows you to store your trim settings in the transmitter, so that you can recall them for later use, or eliminate the need of having to readjust with every time if you have multiple devices. RC car remotes are often equipped with dual rates, expo, memory, and even telemetry.

Most Transmitters need to bind to your Receiver to ensure proper communications. How to do this depends on your Transmitter/receiver.

Many transmitters need 12v to operate, usually supplied by 8AA batteries. this is 8 batteries too many for me, so i got a small, 0.8Ah battery and hooked it up to my remote, so that i only have one battery to worry about, instead of 8 small ones.

A cheap, beginner-level Transmitter that i can recommend from personal experience is the HobbyKing 6S.

Step 3: The Reciever

Picture of The Reciever
The receiver, abbreviated as Rx, receives the signals of the transmitter, and sends them out to the individual channels through PPM, or Pulse Position Modulation commands.

The Receiver must operate on the same frequency as the transmitter, and the two will usually be sold together.  Replacement or extra receivers are commonly available, so that they do not need to be switched out if one has more than one devices requiring a receiver.

The receiver usually receives power from a motor controller, simply by plugging it into one of the signal ports. Servos receive power from the receiver.

The Polarity of the plugs is usually found out by trial and error, in one way it will work, and the other way it probably will show a flashing light or something similar. Make sure to never connect one wire one way and another with opposite polarity to that wire, because depending on what those two things are, they will most likely be damaged, because one is going to be reverse polarity.

Some servo or motor controller connectors have a small plastic tab on them, and can therefore only be used with RC car receivers that can easily be removed with wire cutters.

Be careful with the antennae of digital receivers, because they are rather difficult to reattach.

Step 4: Servos

Picture of Servos
Servos are geared motors connected to potentiometers that are usually capable of 180 degree rotation, but with RC control usually only rotate 90 degrees. They take the receiver's commands in PPM form and rotate to a set position. they will attempt to hold this position if f force is applied. Although normal servos have a limited range, there are extended range servos, which rotate 360 degrees or more, and even continuous rotation servos, which have no control electronics and function as a normal gear motor.

They all have the standard three pin connectors, with ground (black), +4.8 to 7.4v (red), and signal (white).

Servo s are usually classified by weight, and also have a torque rating. This rating is usually given in Kg.
What this means is that the servo has x Kg force one centimeter out from the axis of rotation. So a 50Kg servo could supply 50Kg of force 1cm out from the axis (or 25kg 2cm out from the axis, etc...).

Some Large servos need a separate power supply because of their current demands, and would most likely just burn through your speed controller's power supply or your receiver's PCB traces. Use an UBEC with these. this is basically just a step down voltage regulator that provides a constant voltage to your servos.

Step 5: Motor Controllers

Picture of Motor Controllers
Motor controllers, also known as ESC's (Electronic Speed Controller) are very simple to use. Their purpose is to take a low power input signal in the form of ppm, and the battery voltage, and convert it into something useful for the motor. They also have a voltage output through the signal wire, and are often used to power the receiver.

There are essentially two types of motor controllers: brushless and brushed controllers. Brushed motor controllers only work with brushed motors, and send them a PWM, a Pulse Width Modulated (not PPM, Pulse Position Modulated) power input. These are simple and cheap, and can also be used to control lights and anything else that requires DC power. Brushless motor controllers are quite different. They switch power between the three combinations of two of the three poles of a brushless motor, and modulate the speed of this according to the PPM signal.

The difference between Car ESC's and Airplane ESC's is that car ESC's usually come with a power switch, heat sink and a reversing ability, while airplane ESC's have no reversing capability (Switch any two of the motor wires to reverse spin of the motor), no power switch and usually only a minimal heat sink.

ESC's are also programmable, usually through a programming card or through the reciever and transmitter. This will vary depending on the ESC, but usually they have programmable braking, starting, and battery voltage cutoff settings.

Step 6: Motors, Propellers and Gears

Motors come in two variants: Brushed motors, which have small brushes that switch the power through the coils, and brushless motors, which need an external controller to do the switching for them.

Brushless motors are usually more efficient, can handle higher speeds and torques, can handle huge amounts of power, and are longer lasting because they do not have brushes to wear out. they usually come in out-runner or in-runner styles. Outrunners have the permanent magnets on the outside, and their housing spins with the axle. Inrunners have the permanent magnets on the inside and have a non-rotating housing. Outrunners have more torque, but less speed, and are usually used with larger propellers. Inrunners have less torque, but can reach very high speed, and are therefore used in geared applications, such as RC cars, or with small propellers.

Motors in the RC world often have an interesting rating called Kv. Although one would expect this to mean Kilovolts, it actually means rotations per minute per volt. A 300Kv motor would, in theory, rotate at 900rpm at 3 volts. the lower the Kv rating, the more torque but the less speed a motor has, and the higher, the more speed but less torque a motor would have.

When looking for a suitable propeller, the prospective buyer may be confronted with such things as "1247" or "12x4.7". These define the propeller's size and pitch. in this instance, one would be looking at a 12 inch diameter, 4.7 inch pitch propeller. Pitch is defined as the distance a propeller would move in the air under ideal conditions in one full rotation. Propellers are also often classified into "slow fly" and normal propellers. Slow fly propellers are usually for geared applications or low speed applications, and have a curved leading edge for more efficiency. Normal Propellers have a straight leading edge for better efficiency, and are usually used with faster motors.

Gears in the RC world are usually only sold as a replacement for RC car gearboxes. they are never sold by diameter, but only by the pitch (spacing of the teeth) and the number of the teeth. A Spur gear is usually a large gear, that is turned by the pinion, a smaller gear directly attached to the motor. 

Step 7: Batteries and Chargers

Batteries come in many different Shapes and sizes, chemistries, and ratings.

The two most common chemistries for RC applications are NiMH or NiCd and Lithium polymer batteries.

NiMH (Nickel metal hydride) and NiCd  (Nickel-Cadmium) batteries are heavy, weak and outdated. the only benefit is that they may be marginally cheaper, and less sensitive to shock, vibration, overcharging, and deep discharge.

Lithium Polymer Batteries are lighter, smaller, can deliver huge currents, and have a very large capacity for their size. A 5000mAh Lipo battery is about as big and heavy as 2500mah worth of NiMH batteries. however, if pierced, discharged too far, or charged too far, they will "puff", or expand. This means that the battery is close to exploding. do not use this battery anymore, and dispose of it safely. If you keep going, it will most likely erupt in a large ball of flame and launch chemicals and burning things everywhere. Never short these batteries, they will most likely explode.

Charging: get yourself a good charger, I can recommend the Turnigy Accucell-6. Most chargers do not come with a built in power supply, so make sure you have an adequate power supply for your charger. Follow all the charging instructions that come with the charger, and place your battery in a fireproof container or bag. Never leave it unattended while charging.

Batteries have a number of different ratings:

mAh or Ah:  Stand for milliamp hour or Amp hour. this is the capacity of the battery. 1Ah=1000mAh, which means a battery can supply one amp for one hour (or 1000milliamps for an hour)
S and P:       Stand for number of Series cells and number of parallel cells. the number of cells in series determines voltage, parallel determines capacity.
C ratings:     This is how much current the battery can give you. Multiply the battery's capacity in amp hours by this rating to get the current in amps.  There are usually two specified. the lower one is the continuous rating, and the higher one is the pulse discharge rating.

I usually use one standardized connector for all of my batteries, so that I can use any battery with any device, and can interchange them easily. It doesn't matter what you use, I use the XT60 connectors, just make sure that you have one type of connector for all of your batteries.

Get some silicone wire for your power connections, because it is a flexible, multi-stranded wire that will in general make your life many times easier.

Step 8: Final Comments

Picture of Final Comments
Thanks for taking the time to look at this guide. I hope you enjoyed it and that i could be of some help. I am by no means an expert in this area, and would love to get some tips on how to improve this guide, things to add, questions or comments. 

Please VOTE FOR ME in the Remote Controlled Challenge!
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Borg1012 years ago
For a complete RC noob, like myself - This guide was very helpfull.
biolethal (author)  Borg1012 years ago
Awesome, thanks!
bodger-bill3 months ago

Thank you for a very interesting article, however I still couldn't find the small piece of information I have been searching for

How slow will these motors go, assuming a slow pulse driver is connected !

It looks as though one of these motors could be modified to have a hollow centre shaft, therefore, they probably would be suitable for driving the cross slides on a small mill, power would be no problem, and it would not be necessary to disengage the shaft before changing to manual mode

Any thoughts would be helpful, but please don't just say I should be using stepper motors

biolethal (author)  bodger-bill1 month ago

These motors will spin at a minimum rpm of approximately 100. With some gearing, they could easily drive cross slides, and if you just need a constant feed rate you might even be able to get away with a decent speed controller and servo tester setup. The reason people use stepper motors is that stepper motors have much finer/more controlled positioning (1.8 degrees per step vs about 30 for most rc motors), and the drivers for steppers are designed to step a certain amount of steps rather than maintain an approximate speed as in an rc motor driver.
I don't see why you would have to disengage a stepper to use manual feed, perhaps it is because the electricity generated by spinning the motor would fry the control circuits? In that case, you could just add an electronic disconnect switch.

Dear Sir
Much obliged for the information, I'm only just getting into brush-less motors, and finding that although there's is a lot of information from the manufactures point of view, it's not much help to someone not familiar with the individual terms ?, (Still hopefully searching for a good helpful book on the subject)
Many thanks again
voaferro13 months ago

"Older, analog TX"? MY LEFT FOOT is analog... Ever since about 1966 that these are known as Digital Proportional - GO READ YOUR HISTORY ON THIS:

SamB45 months ago

Just what I've been looking for, thanks very much!

I must say, This has to be one of the best "Welcome to the World of RC" posts I've ever read. Thank you immensely for your post.

biolethal (author)  Robert_Hatalla5 months ago
Thank you, that made my day!
A Diabetic1 year ago
Awesome guide! I am making an RC submarine and had no idea why I needed an ESC or how to connect my servos and motor to the transmitter. Thanks a ton.

Won't radio reception be a problem under water though?

it works to a limited depth. Particulates (salt, chlorine, etc.) effect range, but you can get an average of 6 - 8 feet of reception in fresh water.

excalibur28116 months ago

An excellent all round guide! Thank you for taking the trouble to put this together.

There is one area which is still a mystery to me. Namely I cannot understand why some motors have such high current requirements. frankly speaking the motors I am familiar with are those I scavenged from various printers (which are brushed 12 Volt motors which do not seem to require much current but spin quite fast) and also brushless motors such as those used in a cd drive (which also seem to need little current and spin very fast), so when I see adverts for ESCs that can deliver 30 Amps or more, I get a little confused. Could I use the typical CD motor for a quadcopter for instance and if so why are such heavy current demands and dangerous LIPOs needed?

biolethal (author)  excalibur28116 months ago

As far as the motors go, the small cd drive motors won't work because while while they may spin fast, they cannot supply a lot of torque. You can test this by trying to stop one of these motors with your hand: it is very easy to slow them down. While the big, high current motors spin at close to the same speed, they can supply a lot more output power, and therefore more torque. This means that if you try to stop one of these motors with your hand, it is a lot more difficult to do so. In practice, this means that they won't slow down with a big propeller attached to them, and therefore will be able to create enough lift for a quadcopter. The LiPo batteries are in turn needed to power the large motors.

Thanks again. Interestingly I did some further reading and found that apparently there are people who "beef up" CD motors by messing about with their internals to improve performance and then these motors do become useful for quadcopters and so on. But apparently not "out of the box", except for really small quadcopters.

sangam_cm9 months ago
Sir, I read your article. Liked it a lot. I'm interested in building a rc helicopter. What all extra electronic components are required other than what you've mentioned?
you need a gyro and maybe 2 batteries
biolethal (author)  sangam_cm9 months ago
Are you planning on building a quadopter/multicopter or a real helicopter (single rotor)?
AutoPus10 months ago

Hey I loved reading your guide and I would just like to know if you could give me a few more suggestions for a transmitter am looking for the same basic cheap type and would like to know if I have any other options... a bit more expensive wouldn't hurt either. Thanks.

biolethal (author)  AutoPus10 months ago

Thanks! There's a few good options out there: there's obviously the really cheap stuff (<$50), and that is all about the same quality, and usually doesn't include a screen or any kind of programmability. If you are willing to spend more than that, I hear (though i have no personal experience) the Turnigy 9X 9Ch transmitter from hobbyking is definitely the best value for your money. It offers 9 channels, a long range, and programmability. For $60 or so you get the transmitter and a receiver, and 9 channels are more than you'll probably ever need. If you're looking for better quality but less channels, look at the spectrum line of radios from horizon hobby. I've had a spectrum Dx7s radio from them for the past two years and couldn't be happier with it. It is a significant step up in price though.

hope that helps, let me know if you have any other questions.

jmaag1 year ago

i would like to use a nano hooked to my futaba rc receiver to control multiple lites on my quad. Can you help me

biolethal (author)  jmaag1 year ago

would you mind clarifying what this "nano" is? There are many RC electronics products out there with "nano" in their brand name.

Otherwise, I could guess that HobbyKing's "9 mode multi colour/multi function LED strip with control unit" might help you. I have had success with it in the past.

I looked at it and it does not function the way I want. It looks like it has to cycle through to turn off the lights. I came up with my own design. Mine has 8 multi-switches from one channel. I can turn each switch on or off individually such as number 5 on, then number 5 off or the same with any other switch or turn on 3, 6, 7 on and then just 6 off.

biolethal (author)  jmaag1 year ago

It has multiple modes, and every time you switch it on/off it goes to a new mode. one of these is indeed cycling through colors, but I believe it also has fixed color modes.

ok, never seen that, but I designed mine that the first 4 are solid on, the next 3 are flashing and the last one is double flash like a strobe.

fatdumpa1 year ago
anyone know where to find info on pairing props/motors/escs/batteries/chargers? me and a mate are thinking of building a simple tri-copter on the cheap.

You can use eCalc to get a rough idea

biolethal (author)  fatdumpa1 year ago
check out
He has a great tricopter build and shows what motors and esc's he uses.
What servo would you recommend for a helicopter?

digital servos with a high speed 0.08 seconds or faster. The size depends on your heli class (a 450 class usually has 20 grams servos) . For larger (more expensive) helis I would recommend getting highly rated servos designed for heli applications. Have fun flying!

Thaikarl1 year ago
Thanks so much! I only recently got interested in RC planes. There's a lot of information out there, but it gets confusing - so many numbers, specs, techs. this is really helpful to see the whole system ias components without a lot of clutter. I feel like i have a place to start from now.
coolghoul1 year ago
actually,this was really helpful.Thanks!!!
Very good guide and instructions clearly . Thank you
acunliffe11 year ago
Thanks for the great guide. Really helped me. Although you say you connect the battery to the esc but I will be having two motors and therefore two escs'. Do I connect the battery to one esc? And what battery do you recommend; there will be 1 servo and two motors on the boat
DJNASHA1 year ago
canu tell us what type of transistor used in r/c recivers thanks
acunliffe11 year ago
Great guide for the beginner in rc which I am. Although you say you connect the battery to the esc but I will be having two motors and escs so do I connect it to just one esc? And what battery would you recommend? I am having two motors and a servo.
Fabulous.... You've answered heaps of the jargon for me...
biolethal (author)  michaelmacnz2 years ago
glad i could help :)
double_g2 years ago
Thanks for the instructable! This cleared up some things which I've struggled to find answers to such as how to convert C ratings into current! Already favorited!
biolethal (author)  double_g2 years ago
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