The Current Advances of PCB Motors

There’s something to be said about the falling costs of printed circuit boards over the last decade. It’s opened up the world of PCB art, yes, but it’s also allowed for some experimentation with laying down fine copper wires inside a laminate of fiberglass and epoxy. We can design our own capacitive touch sensors. If you’re really clever, you can put coils inside four-layer PCBs. If you’re exceptionally clever, you can add a few magnets and build a brushless motor out of a PCB.

We first saw [Carl]’s PCB motor at the beginning of the year, but since then we’ve started the Hackaday Prize, [Carl] entered this project in the Prize, and this project already made it to the final round. It’s really that awesome. Since the last update, [Carl] has been working on improving the efficiency and cost of this tiny PCB motor. Part of this comes from new magnets. Instead of a quartet of round magnets, [Carl] found some magnets that divide the rotor into four equal pieces. This gives the rotor a more uniform magnetic field across its entire area, and hopefully more power.

The first version of this 3D printed PCB motor used press-fit bushings and a metallic shaft. While this worked, an extra piece of metal will just drive up the cost of the completed motor. [Carl] has redesigned the shaft of the rotor to get rid of the metallic axle and replace it with a cleverly designed, 3D printed axle. That’s some very nice 3D printing going on here, and something that will make this motor very, very cheap.

Right now, [Carl] has a motor that can be made at any board house that can do four-layer PCBs, and he’s got a rotor that can be easily made with injection molding. The next step is closed-loop control of this motor. This is a challenge because the back-EMF generated by four layers of windings is a little weak. This could also be accomplished with a hall sensor, but for now, [Carl] has a working PCB motor. There’s really only one thing to do now — get the power output up so we can have real quadcopter badges without mucking around with tiny brushed motors.

[Carl] has put up a few videos describing how his PCB motor works; you can check those out below.
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Completely Scratch-Built Electronic Speed Controller

Driving a brushless motor requires a particular sequence. For the best result, you need to close the loop so your circuit can apply the right sequence at the right time. You can figure out the timing using a somewhat complex circuit and monitoring the electrical behavior of the motor coils. Or you can use sensors to detect the motor’s position. Many motors have the sensors built in and [Electronoobs] shows how to drive one of these motors in a recent video that you can watch below. If you want to know about using the motor’s coils as sensors, he did a video on that topic, earlier.

The motor in question was pulled from an optical drive and has three hall effect sensors onboard. Having these sensors simplifies the drive electronics considerably.

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IQ Makes Smarter Motors

We think of motors typically as pretty dumb devices. Depending on the kind, you send them some current or some pulses, and they turn. No problem. Even an RC servo, which has some smarts on board, doesn’t have a lot of capability. However, there is a new generation of smart motors out that combine the mechanical motor mechanism with a built-in controller. [Bunnie] looks at one that isn’t even called a motor. It is the IQ position module.

Despite the name, these devices are just a brushless DC motor (BLDC) with a controller and an API. There’s no gearing, so backdriving the motor is permissible and it can even double as a motion sensor. The video below shows [Bunnie] making one module track the other using just a little bit of code.

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This Tiny Motor is Built into a PCB

Mounting a motor on a PCB is nothing new, right? But how about making the PCB itself part of the motor? That’s what [Carl Bugeja] has done with his brushless DC motor in a PCB project, and we think it’s pretty cool.

Details on [Carl]’s Hackaday.io page are a bit sparse at this point, but we’ve been in contact with him and he filled us in a little. The PCB contains the stator of the BLDC and acts as a mechanical support for the rotor’s bearing. There are six spiral coils etched into the PCB, each with about 40 turns. The coils are distributed around the axis; connected in a wye configuration, they drive a 3D-printed rotor that has four magnets pressed into it. You can see a brief test in the video below; it seems to suffer from a little axial wobble due to the single bearing, but that could be handled with a hat board supporting an upper bearing.

We see a lot of potential in this design. [Carl] mentions that the lack of cores in the coil limit it to low-torque applications, but it seems feasible to bore out the center of the coils and press-fit a ferrite slug. Adding SMD Hall sensors to the board for feedback would be feasible, too — in fact, an entire ESC and motor on one PCB could be possible as well. [Carl] has promised to keep the project page updated, and we’re looking forward to more on this one.

For a more traditional approach to printed motors, check out this giant 3D-printed BLDC.

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Fidget Spinner Becomes a Brushless Motor; Remains Useless

Your grandmother means well. But by the time she figures out something’s a fad, it is old news. So maybe you got a fidget spinner in your stocking this year. Beats coal. Before you regift it to your niece, you could repurpose it to be a motor. Technically, [B.Aswinth Raj] made a brushless motor, although it isn’t going to fly your quadcopter anytime soon, it is still a nice demonstrator.

You can see a video below. The idea is to put magnets on the spinner and use an electromagnet to impart energy into the spinner which is on a piece of threaded rod left over from your last 3D printer build. A hall effect sensor determines when to energize the electromagnet.

A brushed motor uses a spring-loaded brush to carry current through to the motor’s coils and keep the magnetic field oriented properly. A brushless motor works differently. There are several schemes that will work, but the one [Raj] uses is the most common. He adds fixed magnets on the rotor then uses an electromagnet to provide the correct push at the right time. A practical brushless motor will likely have more than one coil, though, and the controller has to do a particular sequence to move the rotor around the rotation.

If you want to see the insides of a real motor, we looked at how to rewind them earlier. If you’d rather repurpose your spinner to something more practical, you could always make some music.

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3D-Printed Halbach Motor Part Two: Tuning, Testing

Building your own Halbach-effect brushless DC motor is one thing. Making sure it won’t blow up in your face another matter, and watching how [Christoph Laimer] puts his motor to the test is instructive.

You’ll remember [Christoph]’s giant 3D-printed BLDC motor from a recent post where he gave the motor a quick test spin. That the motor held together under load despite not being balanced is a testament to the quality of his design and the quality of the prints. But not wishing to tempt fate, and having made a few design changes, [Christoph] wisely chose to perform a static balancing of the rotor. He also made some basic but careful measurements of the motor’s parameters, including the velocity constant (Kv) using an electric drill, voltmeter, and tachometer, and the torque using a 3D-printed lever arm and a kitchen scale. All his numbers led him to an overall efficiency of 80%, which is impressive.

[Christoph] is shipping his tested BLDC off to the folks at FliteTest, where he hopes they put it to good use. They probably will — although they might ask for three more for a helicarrier.

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Fly Across the Water on a 3D-Printed Electric Hydrofoil

Paddleboards, which are surfboard-like watercraft designed to by stood upon and paddled around calm waters, are a common sight these days. So imagine the surprise on the faces of beachgoers when what looks like a paddleboard suddenly but silently lurches forward and rises up off the surface, lifting the rider on a flight over the water.

That may or may not be [pacificmeister]’s goal with his DIY 3D-printed electric hydrofoil, but it’s likely the result. Currently at part 12 of his YouTube playlist in which he completes the first successful lift-off, [pacificmeister] has been on this project for quite a while and has a lot of design iterations that are pretty instructive — we especially liked the virtual reality walkthrough of his CAD design and the ability to take sections and manipulate them. All the bits of the propulsion pod are 3D-printed, which came in handy when the first test failed to achieve liftoff. A quick redesign of the prop and duct gave him enough thrust to finally fly.

There are commercially available e-foils with a hefty price tag, of course; the header image shows [pacificmeister] testing one, in fact. But why buy it when you can build it? We’ve seen a few hydrofoil builds before, from electric-powered scale models to bicycle powered full-size craft. [pacificmeister]’s build really rises above, though.

[pacificmeister], if you’re out there, this might be a good entry in the Hackaday Prize Wheels, Wings, and Walkers round. Just sayin’.

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