PCBs As Linear Motors

June 11, 2018 by Brian Benchoff 33 Comments

PCBs are exceptionally cheap now, and that means everyone gets to experiment with the careful application of copper traces on a fiberglass substrate. For his Hackaday Prize entry, [Carl] is putting coils on a PCB. What can you do with that? Build a motor, obviously. This isn’t any motor, though: it’s a linear motor. If you’ve ever wanted a maglev train on a PCB, this is the project for you.

This project is a slight extension of [Carl]’s other PCB motor project, the aptly named PCB Motor. For this project, [Carl] whipped up a small, circular PCB with a few very small coils embedded inside. With the addition of a bearing, a few 3D printed parts, and a few magnets, [Carl] was able to create a brushless motor that’s also a PCB. Is it powerful enough to use in a quadcopter? Probably not quite yet.

Like [Carl]’s earlier PCB motor, this linear PCB motor follows the same basic idea. The ‘track’, if you will, is simply a rectangular PCB loaded up with twelve coils, each of them using 5 mil space and trace, adding up to 140 turns. This is bigger than the coils used for the (circular) PCB motor, but that only means it can handle a bit more power.

As for the moving part of this motor, [Carl] is using a 3D printed slider with an N52 neodymium magnet embedded inside. All in all, it’s a simple device, but that’s not getting to the complexity of the drive circuit. We’re looking forward to the updates that will make this motor move, turning this into a great entry for The Hackaday Prize.

Ask Hackaday: What Color Are Your PCBs?

June 11, 2018 by Brian Benchoff 71 Comments

A decade ago, buying a custom-printed circuit board meant paying a fortune and possibly even using a board house’s proprietary software to design the PCB. Now, we all have powerful, independent tools to design circuit boards, and there are a hundred factories in China that will take your Gerbers and send you ten copies of your board for pennies per square inch. We are living in a golden age of printed circuit boards, and they come in a rainbow of colors. This raises the question: which color soldermask is most popular, which is most desirable, and why? Seeed Studio, a Chinese PCB house, recently ran a poll on the most popular colors of soldermask. This was compared to their actual sales data. Which PCB color is the most popular? It depends on who you ask, and how you ask it.
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Tiny $25 Spectrometer Aims To Identify Materials With Ease

May 29, 2018 by Donald Papp 59 Comments

Reflectance spectrometers work on a simple principle: different things reflect different wavelengths in different amounts, and because similar materials do this similarly, the measurements can be used as a kind of fingerprint or signature. By measuring how much of which wavelengths get absorbed or reflected by a thing and comparing to other signatures, it’s possible to identify what that thing is made of. This process depends heavily on how accurately measurements can be made, so the sensors are an important part.

[Kris Winer] aims to make this happen with the Compact, $25 Spectrometer entry for The 2018 Hackaday Prize. The project takes advantage of smaller and smarter spectral sensors to fit the essential bits onto a PCB that’s less than an inch square. If the sensors do the job as expected then that’s a big part of the functionality of a reflectance spectrometer contained in a PCB less than an inch square and under $25; definitely a feat we’re happy to see.

Tiny Sideways Tetris On A Business Card

May 20, 2018 by Donald Papp 15 Comments

Everyone recognizes Tetris, even when it’s tiny Tetris played sideways on a business card. [Michael Teeuw] designed these PCBs and they sport small OLED screens to display contact info. The Tetris game is actually a hidden easter egg; a long press on one of the buttons starts it up.

It turns out that getting a playable Tetris onto the ATtiny85 microcontroller was a challenge. Drawing lines and shapes is easy with resources like TinyOLED or Adafruit’s SSD1306 library, but to draw those realtime graphics onto the 128×32 OLED using that method requires a buffer size that wouldn’t fit the ATtiny85’s available RAM.

To solve this problem, [Michael] avoids the need for a screen buffer by calculating the data to be written to the OLED on the fly. In addition, the fact that the smallest possible element is a 4×4 pixel square reduces the overall memory needed to track the screen contents. As a result, the usual required chunk of memory to use as a screen buffer is avoided. [Michael] also detailed the PCB design and board assembly phases for those of you interested in the process of putting together the cards using a combination of hot air reflow and hand soldering.

PCB business cards showcase all kinds of cleverness. The Magic 8-Ball Business Card is refreshingly concise, and the project that became the Arduboy had milled cutouts to better fit components, keeping everything super slim.

One-key Keyboard Is Exercise In Sub-millimeter Design

May 19, 2018 by Donald Papp 15 Comments

As [Glen] describes it, the only real goal in his decision to design his single-key USB keyboard was to see how small he could build a functional keyboard using a Cherry MX key switch, and every fraction of a millimeter counted. Making a one-key USB keyboard is one thing, but making it from scratch complete with form-fitting enclosure that’s easy to assemble required careful design, and luckily for all of us, [Glen] has documented it wonderfully. (Incidentally, Cherry MX switches come in a variety of qualities and features, the different models being identified by their color. [Glen] is using a Cherry MX Blue, common in keyboards due to its tactile bump and audible click.)

[Glen] steps though the design challenges of making a device where seemingly every detail counts, and explains problems and solutions from beginning to end. A PIC16F1459, a USB micro-B connector, and three capacitors are all that’s needed to implement USB 2.0, but a few other components including LED were added to help things along. The enclosure took some extra care, because not only is it necessary to fit the board and the mounted components, but other design considerations needed to be addressed such as the depth and angle of the countersink for the screws, seating depth and clearance around the USB connector, and taking into account the height of the overmold on the USB cable itself so that the small device actually rests on the enclosure, and not on any part of the cable’s molding. To top it off, it was also necessary to adhere to the some design rules for minimum feature size and wall thicknesses for the enclosure itself, which was SLS 3D printed in nylon.

PCB, enclosure, software, and bill of materials (for single and triple-key versions of the keyboard) are all documented and available in the project’s GitHub repository. [Glen] also highlights the possibility of using a light pipe to redirect the embedded LED to somewhere else on the enclosure; which recalls his earlier work in using 3D printing to make custom LED bar graphs.

The Current Advances Of PCB Motors

May 12, 2018 by Brian Benchoff 9 Comments

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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Stylish Business Card With A Stylophone Built In

May 11, 2018 by Dan Maloney 19 Comments

If you’re in the electronics business, PCB business cards seem like a natural fit. They may be impractical and expensive, but they can really set you apart from that boring paper card from Vistaprint crowd. But they need to make sense for what you do, so for a musician and MIDI pro, this MIDI-controller stylophone business card is a real eye- and ear-catcher.

This business card is an idea that [Mitxela] has been kicking around for a while, and he even built a prototype a couple of years ago. The homebrew card, made using the spray paint, laser etching, and ferric chloride method, worked well enough as a proof of concept, but it was a little rough around the edges and needed the professional touch of a PCB fabricator. We’ve got to say that the finished cards are pretty darn sexy, with the black resist contrasting nicely against the gold-immersion pads. He selected a 1-mm thick board and made the USB connector as a separate small board; snapped off of the main board and reflowed back on, it builds up the edge connector to the proper thickness. The parts count is low — just an ATtiny85 and a resistor ladder to encode each key, with a simple jumper used as the stylus. The device itself is just a MIDI controller and makes no music on its own, but we still think this is a pretty creative way to hang out a shingle.

[Mitxela] has quite a few interesting builds, and is no stranger to our pages. Check out his recent servo-plucked MIDI music box, or these amazing miniature LED earrings.

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