How does an RC car work? Hobby Electronics Explained for Beginners!

[00:00:00] Speaker 1: Hello everybody. In this video we'll go over the major electronic components of an RC car. We'll look at how they are powered and how you actually control your remote-controlled car remotely. Isn't that right Blitzy? Oh Blitzy. Anyway, think of your battery as the fuel tank of your car. AG is stored here and it's what makes the car go. There's two main things you need to know about batteries. Voltage and capacity. Essentially, voltage dictates how fast your RC vehicle will go. With electric motors spinning faster, the more volts they are supplied with. But there is a limit. Plug 16 volts into something that is only designed to handle 8 and it'll burn out almost immediately. And once electronics let out the magic smoke of destruction, there's no way to put it back in. The capacity of the battery is measured in MAH or milliamp hours. If your battery has a capacity of 5000 milliamp hours, that's the same thing as 5 amp hours. That means that if you put a 5 amp current drain on that battery, it would take an hour to run flat. If you put a 10 amp drain on it, it would only take half an hour and so on. This is why the same battery in two different cars can give two very different run times. The battery gets plugged into the ESC or electronic speed controller. It controls the speed of the car by controlling the amount of power that is allowed to transfer from the battery into the motor. Some modern ESCs can be programmed with all sorts of different settings like turbo, timing, acceleration curves and more. But in essence the more power the ESC sends to the motor, the faster you go. Brushless motors are rated in KV, which is not kilovolts, though I feel like it should be. KV is actually the RPM. Revolutions per minute, the motor will do per volt of electricity that it's given. If a 3300 KV motor is given one volt, it'll spin at 3300 RPM, 2 volts, 6600 RPM, and so on. This means your HSP Mongoose BL's motor, for example, is spinning at nearly 28000 RPM at full throttle. That's more than 450 revolutions every second. So, more KV, more better, yeah? Well, sometimes. But in general, as cars get bigger, heavier and faster, you'll see their motors also get bigger and the KV number go down. With brushless motors, less KV is more torque, and you need lots of torque to move a 12 kilogram car. Brushed motors are measured in turns, with a lower number of turns giving a faster spinning motor. But like brushless motors, you get nothing for nothing. It's all about balance. Too many turns, and the car will be slow. And unless you're going for a torque monster crawler build, it's usually not fun. But go too low on turns, and you'll have something ballistically fast, for about three minutes, until it burns out. 23 turns for buggies, and 35 turns for crawlers, seems to be a good starting point. And don't panic if your motor is spinning the wrong way after you've taken everything apart and put it back together. On brush motors, you can just swap the two motor wires to reverse motor direction. On sensorless brushless motors, you can swap any two of the three motor wires to reverse the direction. You can't do this on sensorless motors. They have very specific A, B and C phase wires that need to be matched to the A, B and C phases of the ESC. But, sensorless ESCs have motor rotation in their programming menu, so you can still get it sorted. So while the electronic speed controller is responsible for sending the battery's power to the motor, it also sends a small amount to the receiver. This power flows through the receiver to also power your steering servo. It does this by utilizing an internal voltage regulator and current supply, known as a BEC. A BEC, or B-E-C, actually stands for battery eliminator circuit. This is because in the old days of nickel cadmium batteries, these circuits were used to power radio gear and servos instead of the main battery, which could then focus on just powering the motor. Another carryover from way back when is the use of six-volt receivers and servos. Of course, there are receivers and servos capable of taking much higher voltages, but the majority of ready-to-run cars still use six volts. Regardless of the amount of volts that your battery has, the ESC's internal BEC will step this voltage down to six volts, so you don't toast your receiver and servo. But say both your receiver and servo are rated for more, like 7.4 volts, and you want the increased strength and speed that comes with it. A lot of modern ESCs have variable BEC voltage output that you can program to match the specs of higher-end servos. Make sure you double-check that you have higher voltage compatible stuff before you go upping the BEC output voltage. Now, onto servos. Most RC servos have a total of 120 degrees of travel, split equally between 60 left and 60 right. Servo torque is rated in kilograms per centimeter by rational people, or ounces per inch in Murica. What this means is that for a 20-kilogram servo, one centimeter out from the output shaft, you have 20 kilograms of twisting force. Two centimeters out, you have 10, and so on. Big power servos that have to shift a lot of weight also have pretty hefty power demands, and a lot of internal BECs can be overwhelmed and start to glitch out, causing losses in signal or jittery steering. These are called brownouts and are cured by the use of an external BEC. This takes its power directly from your battery and steps it down to the right voltage for your servo, taking any limitations of the internal BEC completely out of the equation. So, in summary, the battery powers the ESC and external BEC, if you've used one, which then sends power to the motor. The ESC also powers the receiver and in turn the steering servo. So, that's how your RC is powered, but how do you actually control it? Most RC cars have a two-channel radio setup. One channel for steering, one channel for throttle and brake. When you accelerate or steer, your radio transmits this as radio frequency information until it is picked up by the receiver. From there, the receiver relays this information to either the steering servo or the electronic speed controller. You may have noticed that both the car's ESC and the steering servo have a three-wire connector coming out of them. Red and black are positive and negative. This is how the servo gets its power from the receiver, and how the ESC sends power to the receiver. The third wire is usually white, and is the signal wire. Each channel performs a movement or function, and it's through this white signal wire that they get this information. Hobby-grade RC cars all have proportional controls. This means that the steering and throttle don't operate like two position switches in an all-or-nothing fashion. Rather, they will steer or accelerate only as much as you turn the wheel or pull the trigger. This is great, because when it's all your precise movements that totally nailed that wicked sick drift, you get all the credit. Unfortunately, you get full credit for all those crashes and rolls too, unless no one's watching. That's right. Thank you so much for watching. Remember to like, comment, subscribe, and I'll see you in the next video. Bye.