Rudolph’s Sleigh On A North Pole PCB

December 20, 2024 by Heidi Ulrich 6 Comments

Each Christmas, [Adam Anderson], [Daniel Quach], and [Johan Wheeler] (going by ‘the Janky Jingle Crew’)—set themselves the challenge of outdoing their previous creations. Last year’s CH32 Fireplace brought an animated LED fire to life with CH32V003 microcontrollers.

This year, they’ve gone a step further with the North Pole Circuit, a holiday project that combines magnetic propulsion, festive decorations, and a bit of engineering flair. Inspired by a miniature speedway based on Friedrich Gauss’ findings, the North Pole Circuit includes sleighs and reindeer that glide along a custom PCB track, a glowing village with flickering lights, and a buzzer to play Christmas tunes.

The propulsion system works using the Lorentz force, where vertical magnets interact with PCB traces to produce motion. A two-phase design, similar to a stepper motor, ensures smooth operation, while guard rails maintain stability on curves. A separate CH32V003 handles lighting and synchronized jingles, creating a cohesive festive display. As we mentioned in the article on their last year’s creation, going from a one-off to a full batch will make one rethink the joy of repetitive production. Consider the recipients of these tiny Christmas cards quite the lucky ones. We deem this little gift a keeper to put on display when Christmas rolls around again.

This annual tradition highlights the Crew’s knack for combining fun and engineering. Curious about the details or feeling inspired to create your own? Explore the full details and files on their GitHub.

PCB Motor Holds Fast, Even After 1.6 Billion Spins

December 17, 2024 by Donald Papp 30 Comments

If you aren’t up to date with [Carl Bugeja]’s work with tiny brushless PCB motors, his summary video of his latest design and all the challenges it involved is an excellent overview.

Back in 2018 we saw [Carl]’s earliest versions making their first spins and it was clear he was onto something. Since then they have only improved, but improvement takes both effort and money. Not only does everything seemingly matter at such a small scale, but not every problem is even obvious in the first place. Luckily, [Carl] has both the determination and knowledge to refine things.

Hardware development is expensive, especially when less than a tenth of a millimeter separates a critical component from the junk pile.

The end result of all the work is evident in his most recent test bed: an array of twenty test motors all running continuously at a constant speed of about 37,000 RPM. After a month of this, [Carl] disassembled and inspected each unit. Each motor made over 53 million rotations per day, closing out the month at over 1.6 billion spins. Finding no sign of internal scratches or other damage, [Carl] is pretty happy with the results.

These motors are very capable but are also limited to low torque due to their design, so a big part of things is [Carl] exploring and testing different possible applications. A few fun ones include a wrist-mounted disc launcher modeled after a Spider-Man web shooter, the motive force for some kinetic art, a vibration motor, and more. [Carl] encourages anyone interested to test out application ideas of their own. Even powering a micro drone is on the table, but will require either pushing more current or more voltage, both of which [Carl] plans to explore next.

Getting any ideas? [Carl] offers the MotorCell for sale to help recover R&D costs but of course the design is also open source. The GitHub repository contains code and design details, so go ahead and make them yourself. Or better yet, integrate one directly into your next PCB.

Got an idea for an application that would fit a motor like this? Don’t keep it to yourself, share in the comments.

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Even Apple Get Their Parts Wrong Sometimes

November 27, 2024 by Jenny List 14 Comments

There can be few among those of us who produce printed circuit boards, who have not at some point placed a component the wrong way round, or with the wrong footprint. Usually this can be rectified with a bit of rework and a fresh board spin, but just occasionally these mishaps make it into the wild undetected. It seems nobody is immune, as [Doug Brown] is here to tell us with a tale of an Apple product with a misplaced capacitor.

The LC series of Macs came out through the early 1990s, and their pizza-box style cases could be found slowly turning yellow in universities and schools throughout that decade. Of them there was a persistent rumor of the LCIII had a misplaced capacitor, so when he received an unmodified original machine he took a look. The investigation is quite simple, but revealing — there are three power supply rails and one of the capacitors does have a significant leak.

The explanation is simple enough, the designer had placed a capacitor on each rail, with its negative side to the ground plane, but one of the rails delivers -5 volts. Thus the capacitor is the wrong way round, and must have failed pretty early in the lifetime of each LCIII. We’re curious then since so many of them went through their lives without the component being replaced, how the circuit remained functional. We’re guessing that there were enough other capacitors in the -5 volt line to provide enough smoothing.

Rapid Prototyping PCBs With The Circuit Graver

November 6, 2024 by Dave Rowntree 27 Comments

Walking around the alley at Hackaday Supercon 2024, we noticed an interesting project was getting quite a bit of attention, so we got nearer for a close-up. The ‘Circuit Graver’ by [Zach Fredin] is an unconventional PCB milling machine, utilizing many 3D printed parts, the familiar bed-slinger style Cartesian bot layout and a unique cutting head. The cutting tool, which started life as a tungsten carbide lathe tool, is held on a rotary (‘R’) axis but can also move vertically via a flexure-loaded carriage driven by a 13 kg servo motor.

The stocky flexure took a lot of iteration, as the build logs will show. Despite a wild goose chase attempting to measure the cutting force, a complete machine solution was found by simply making everything stiff enough to prevent the tool from chattering across the surface of the FR4 blank. Controlling and maintaining the rake angle was a critical parameter here. [Zach] actually took an additional step, which we likely wouldn’t have thought of, to have some copper blanks pre-fabricated to the required size and finished with an ENIG coating. It’s definitely a smart move!

To allow the production of PCB-class feature sizes compatible with a traditional PCB router, the cutting tool was sharpened to a much smaller point than would be used in a lathe using a stone. This reduced the point size sufficiently to allow feature sizes down to 4 mils, or at least that’s what initial characterization implied was viable. As you can see from the build logs, [Zach] has achieved a repeatable enough process to allow building a simple circuit using an SMT 74HC595 and some 0402 LEDs to create an SAO for this year’s Supercon badge. Neat stuff!

We see a fair few PCB mills, some 3D printed, and some not. Here’s a nice one that fits in that former category. Milling PCBs is quite a good solution for the rapid prototyping of electronics. Here’s a guide about that.

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Making PCB Strip Filter Design Easy To Understand

October 28, 2024 by Dan Maloney 4 Comments

We’ve always been fascinated by things that perform complex electronic functions merely by virtue of their shapes. Waveguides come to mind, but so do active elements like filters made from nothing but PCB traces, which is the subject of this interesting video by [FesZ].

Of course, it’s not quite that simple. A PCB is more than just copper, of course, and the properties of the substrate have to be taken into account when designing these elements. To demonstrate this, [FesZ] used an online tool to design a bandpass filter for ADS-B signals. He designed two filters, one using standard FR4 substrate and the other using the more exotic PTFE.

He put both filters to the test, first on the spectrum analyzer. The center frequencies were a bit off, but he took care of that by shortening the traces slightly with a knife. The thing that really stood out to us was the difference in insertion loss between the two substrates, with the PTFE being much less lossy. The PTFE filter was also much more selective, with a tighter pass band than the FR4. PTFE was also much more thermostable than FR4, which had a larger shift in center frequency and increased loss after heating than the PTFE. [FesZ] also did a more real-world test and found that both filters did a good job damping down RF signals across the spectrum, even the tricky and pervasive FM broadcast signals that bedevil ADS-B experimenters.

Although we would have liked a better explanation of design details such as via stitching and trace finish selection, we always enjoy these lessons by [FesZ]. He has a knack for explaining abstract concepts through concrete examples; anyone who can make coax stubs and cavity filters understandable has our seal of approval.

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A Brand-New Additive PCB Fab Technique?

October 27, 2024 by Dan Maloney 68 Comments

Usually when we present a project on these pages, it’s pretty cut and dried — here’s what was done, these are the technologies used, this was the result. But sometimes we run across projects that raise far more questions than they answer, such as with this printed circuit board that’s actually printed rather than made using any of the traditional methods.

Right up front we’ll admit that this video from [Bad Obsession Motorsport] is long, and what’s more, it’s part of a lengthy series of videos that document the restoration of an Austin Mini GT-Four. We haven’t watched the entire video much less any of the others in the series, so jumping into this in the middle bears some risk. We gather that the instrument cluster in the car is in need of a tune-up, prompting our users to build a PCB to hold all the instruments and indicators. Normally that’s pretty standard stuff, but jumping to the 14:00 minute mark on the video, you’ll see that these blokes took the long way around.

Starting with a naked sheet of FR4 substrate, they drilled out all the holes needed for their PCB layout. Most of these holes were filled with rivets of various sizes, some to accept through-hole leads, others to act as vias to the other side of the board. Fine traces of solder were then applied to the FR4 using a modified CNC mill with the hot-end and extruder of a 3D printer added to the quill. Components were soldered to the board in more or less the typical fashion.

It looks like a brilliant piece of work, but it leaves us with a few questions. We wonder about the mechanics of this; how is the solder adhering to the FR4 well enough to be stable? Especially in a high-vibration environment like a car, it seems like the traces would peel right off the board. Indeed, at one point (27:40) they easily peel the traces back to solder in some SMD LEDs.

Also, how do you solder to solder? They seem to be using a low-temp solder and a higher temperature solder, and getting right in between the melting points. We’re used to seeing solder wet into the copper traces and flow until the joint is complete, but in our experience, without the capillary action of the copper, the surface tension of the molten solder would just form a big blob. They do mention a special “no-flux 96S solder” at 24:20; could that be the secret?

We love the idea of additive PCB manufacturing, and the process is very satisfying to watch. But we’re begging for more detail. Let us know what you think, and if you know anything more about this process, in the comments below.

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Hacker Tactic: Building Blocks

October 24, 2024 by Arya Voronova 11 Comments

The software and hardware worlds have overlaps, and it’s worth looking over the fence to see if there’s anything you missed. You might’ve already noticed that we hackers use PCB modules and devboards in the same way that programmers might use libraries and frameworks. You’ll find way more parallels if you think about it.

Building blocks are about belonging to a community, being able to draw from it. Sometimes it’s a community of one, but you might just find that building blocks help you reach other people easily, touching upon common elements between projects that both you and some other hacker might be planning out. With every building block, you make your or someone else’s next project quicker, and maybe you make it possible.

Sometimes, however, building blocks are about being lazy.

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