This Is The Year Of PCB Inductors

It’s a story we’ve told dozens of times already. The cost to manufacture a handful of circuit boards has fallen drastically over the last decade and a half, which has allowed some interesting experiments on what PCBs can do. We’ve seen this with artistic PCBs, we’ve seen it with enclosures built out of PCBs, and this year we’re seeing a few experiments that are putting coils and inductors on PCBs.

At the forefront of these experiments in PCB coil design is [bobricious], and already he’s made brushless and linear motors using only tiny copper traces on top of fiberglass. Now he’s experimenting with inductors. His latest entry to the Hackaday Prize is a Joule Thief, a simple circuit, but one that requires an inductor to work. If you want an example of what can be done with spirals of copper on a PCB, look no further than this project.

The idea was simply to make a Joule Thief circuit. The circuit is not complicated — you only need a transistor, resistor, and an inductor or transformer to boost the voltage from a dead battery enough to light up an LED.

The trick here is that instead of some wire wrapped around a ferrite or an off-the-shelf inductor, [bobricious] is using 29 turns of copper with six mil traces and spacing on a PCB. Any board house can do this, which means yes, you can technically reduce the BOM cost of a Joule Thief circuit at the expense of board space. This is the year of PCB inductors, what else should be be doing with creative PCB trace designs?

Repairing a Capacitor inside a Potted Transformer

We always enjoy watching [Mr. Carlson’s] videos because he looks like he is taping in a rocket ship set from a 1950s drive-in movie. In a recent video, he identified an old oscilloscope that had a transformer assembly that is potted with a pair of capacitor inside. The capacitor failed so [Carlson] decided he would repair it. The problem? The transformer and capacitor are potted together with some sort of tar compound. You can see the result in the video below.

He actually didn’t know for sure the capacitor was really in the transformer, but they were in the schematic and by process of elimination, it had to be inside. Once he liberated the transformer, he did some tests to identify the capacitor before the depotting. The depotting takes a lot of heat and could damage the transformer, so he wanted to make sure it was really in there.

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DIY Coil Winding Machine Counts The Hacky Way

“Wait, was that 423 or 424?” When you’re stuck winding a transformer or coil that has more than a few hundred turns, you’re going to want to spend some time on a winding jig. This video, embedded below, displays a simple but sufficient machine — with a few twists.

The first elaboration is the addition of a shuttle that moves back and forth in sync with the main spindle to lay the windings down nice and smooth. Here, it’s tremendously simple — a piece of threaded rod and a set of interchangeable wheels that are driven by a big o-ring belt. We love the low-tech solution of simply adding a twist into the belt to swap directions. We would have way overthought the mechanism.

But then the hack is the digital counter made out of an old calculator. We’ve seen this before, of course, but here’s a great real-world application.

Thanks [Jānis] for the tip!

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Scrapped Motors Don’t Care About Direction

Spinners built into games of chance like roulette or tabletop board games stop on a random number after being given a good spin. There is no trick, but they eventually rest because of friction, no matter how hard your siblings wind up for a game-winning turn. What if the spinning continued forever and there was no programming because there was no controller? [Ludic Science] shows us his method of making a perpetual spinner with nothing fancier than a scrapped hard disk drive motor and a transformer. His video can also be seen below the break.

Fair warning: this involves mains power. The brushless motor inside a hard disk drive relies on three-phase current of varying frequencies, but the power coming off a single transformer is going to be single-phase AC at fifty or sixty Hz. This simplifies things considerably, but we lose the self-starting ability of the motor and direction control, but we call those features in our perpetual spinner. With two missing phases, our brushless motor limps along in whatever direction we initiate, but the circuit couldn’t be much more straightforward.

This is just the latest skill on a scrapped HDD motor’s résumé (CV). They will run with a 9V battery, or work backwards and become an encoder. If you want to use it more like the manufacturer’s intent, consider this controller.

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Low-End Parts Make Tesla Coil with a High-End Look

We all know the saying: cheap, fast, or good — pick any two. That rule seems to apply across the spectrum of hackerdom, from software projects to hardware builds. But this DIY Tesla coil build might just manage to deliver on all three.

Cheap? [Jay Bowles]’ Tesla coil is based on a handheld bug zapper that you can find for a couple of bucks, or borrow from the top of the fridge in the relatively bug-free winter months. The spark gap is just a couple of screws set into scraps of nylon cutting board — nothing fancy there. Fast? Almost everything needed to build this is stuff lying around the house, and depending on the state of your junk bin you may not even have to order the polypropylene caps [Jay] recommends. Good? That’s a relative term, of course, and if you define it as a coil capable of putting out pumpkin-slaying lightning bolts or playing “Yakkity Sax”, you’ll likely be disappointed. But there’s no denying that this Tesla coil looks good, from its Lexan base to the door-pull top load. And running off a couple of AA batteries, it’s safe to use too.

[Jay] put a lot of care into winding and dressing the secondary coil neatly, and the whole thing would look great as a desktop toy. Not into the winding part? You can always etch a PCB Tesla coil instead.

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Not Your Typical ATX Bench PSU

We know what you’re thinking — yet another scrap PC power supply turned into a bench PSU. But look a little closer and you’ll see a nicely designed linear bench supply that just fits inside a gutted ATX case.

A lot of the items on [Medzik]’s BOM for this build are straight from the scrap bin. The aforementioned ATX supply case is one, as is the power transformer donated by a friend. Modules such as the 30V/2A regulator, the digital volt/ammeter, and a thermostat module to control the fan at higher power settings were all sourced via the usual suspects. The PSU boasts two outputs — an adjustable 0-22 volt supply, and a fixed 12-volt output. An unusual design feature is a secondary input which uses the 22-VAC supply from a Weller soldering station to give the PSU a little more oomph. This boosts the maximum output to 30 volts; one wonders why [Medzik] didn’t just source a bigger transformer, but you work with what you have sometimes. There are some nice touches, too, like custom-printed vinyl overlays for the case.

It’s a good-looking and compact unit with a decent suite of features, and you could do a lot worse when building your next bench supply. If it’s not your cup of tea though, just take your pick — tiny and yellow, built to last, or ensconced in Ultrasuede.

A Thoughtful Variety of Projects and Failures

Our friends at [The Thought Emporium] have been bringing us delightful projects but not all of them warrant a full-fledged video. What does anyone with a bevy of small but worthy projects do? They put them all together like so many mismatched LEGO blocks. Grab Bag #1 is the start of a semi-monthly video series which presents the smaller projects happening behind the scenes of [The Thought Emporium]’s usual video presentations.

Solar eclipse? There are two because the first was only enough to whet [The Thought Emporium]’s appetite. Ionic lifters? Learn about the favorite transformer around the shop and see what happens when high voltage wires get too close. TEA lasers? Use that transformer to make a legitimate laser with stuff around your house. Bismuth casting? Pet supply stores may have what you need to step up your casting game and it’s a total hack. Failures? We got them too.

We first covered ionocraft (lifters) awhile back. TEA lasers have been covered before. Casting is no stranger to hackaday but [The Thought Emporium] went outside the mold with their technique.

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