Make sure the speed control you choose is compatible with SimonK firmware. He reverse engineered a few boards and wrote his own open source firmware with features like soft start, calibration, and easy parameter updates. One more parameter to look at is SimonK firmware. Simon Kirby figured out that many cheap speed controls were running Atmel microcontrollers. Therefore, it’s often a good idea to leave a bit of overhead, lest you let out the magic smoke. Sometimes manufacturers overstate their speed control’s capabilities. Figuring out which to buy is simply a matter of matching one to the motor you plan to use. Speed controls are generally rated by maximum voltage and current. Thankfully those days are gone, and we have cheap MOSFETs around to give us digitally controlled throttles for our brushless motors. In the old days, R/C plane throttles were controlled by a servo moving a switch. These motors are low cost, and should have plenty of power for our quadcopter. A motor capable of handling a voltage of 4S means it’s good for 4 LiPo cells in series, or 14.8V.įor the Hackaday Testbed, I went with the NTM Prop Drive 28-30S 800KV / 300W motor. Sometimes this value is represented in volts, and sometimes in cells, which usually refers to the 3.7V nominal voltage of LIPO cells. The next number to look at is the voltage the motor is rated at. The motor’s RPM will drop significantly when it’s spinning a prop. It’s important to remember that this is a no load rating. A 14.8V 4S LiPo battery will spin the motor at 11,840 RPM. Theoretically, an 800KV motor will turn 800 RPM on a 1V power source. The first and foremost parameter in a motor is KV – Thousands of RPM per Volt. This isn’t a hard and fast rule though, so don’t live by it. A DJI 2212 motor means it has a 22mm diameter stator which is 12mm tall. Motor part numbers are often encoded in terms of stator or can sizes. Once you break it down though, it isn’t too hard. There are a seemingly endless number of parameters to be taken into account. Picking the right power system is a lot like picking the correct microcontroller or op-amp for a circuit design. Power systems have been a tough problem since the early days of radio controlled planes. Changing one for a different model means changing all of them, so it pays to buy a spare or two when ordering! Click past the break for a breakdown of some multicopter parts. But what about motors or speed controls? These components need to be matched on a multicopter. When it comes to single parts like batteries, it’s easy to just order a different size. A popular component will often go out of stock with no hint as to when it will be available again. The killer with many of these companies is supply. If I’ve left out your favorite site, drop some info in the comments section. I’m only listing a few of the big names here. Several Chinese companies, including HobbyKing and RcTimer, maintain warehouses in several parts of the world. Some new US-based companies are All e RC and ReadyMadeRC. In the online world there are several “big” vendors. The classic names in the USA have always been Tower Hobbies and Horizon Hobby. Unfortunately, very few local hobby shops can afford to stock individual parts at that level.
If you really want to dig in and adjust parameters, you have to either buy a combo package with an open source flight control system, or buy every part separately. However, their flight control systems are closed source. Some hobby shops carry the DJI and Blade lines of multicopters. This advice still holds true to a certain extent.
Hook up with a local club and you’ll have some buddies to teach you to fly. There are a myriad of options, and dozens of vendors to choose from.Īdvice was simple in the pre-internet days of R/C planes and helicopters: just head down to your local hobby shop, and see what lines they carry. Which frame, motors, props, speed controller, and batteries are best? There aren’t easy answers to these questions with respect to larger quads (300mm or more). The top question I see when surfing multicopter forums is “What should I buy”. These last few weeks I’ve been ordering parts for the Hackaday Testbed, a basic quadcopter to be used here at Hackaday.
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