Here’s A Tesla Coil You Can Wear

It’s badgelife season, and if you need an idea for a killer piece of wearable electronics, look no further than this PCB Tesla coil. Yes, it’s killer, doubly so if you’re wearing a pacemaker.

This project was inspired by an earlier Tesla coil on a PCB project that used 160 turns of 6 mil traces on a circuit board as the secondary. All the electronics are there, and it’s powered by USB. Plug this thing in, and you have a pocket full of lightning that’s approximately 30kV. It probably won’t kill you if you touch it, but let’s not test that too much. [Bobricious] took this idea and ran with it, stripping the circuit down to its bare minimum. Now it’s just a single transistor, with all the other parts printed on a circuit board.

There is one problem with making a Tesla Coil on a PCB, and that’s the number of turns on the coil. Any Tesla coil you’ll find is really just the clever application of a single thin wire wrapped around itself a few hundred or thousands of times. This Tesla coil is no different, and in this case it’s 240 turns of a single trace wrapping around a PCB that is 150mm square. [Bobricius] is one of the kings of putting tiny coils on a PCB, and his fiberglass brushless motor is a testament to that. We also just covered his circular linear motor raceway which also uses PCB coils.

The circuit is simple, just a power jack that accepts something around 20 Volts, a single BD243 transistor, an LED, and an 82k resistor. With that, you can lay a small neon tube on the PCB and watch it light up. With another PCB and another neon tube, this circuit board can transfer wireless power. It’s a fun toy, and it’s all PCB tech.

The Science Of Reverse Mounted LEDs

One of the most artistic applications of electrical engineering in recent memory is the burgeoning badgelife movement. This is an odd collective of people who are dedicating their time to rendering their own accomplishments in printed circuit boards. Of the entire badgelife collective, one of the most visible efforts are in Shitty Add-Ons, with a particular focus on reverse-mounted LEDs. Yes, you can install SMD LEDs upside down, and if you have your copper layers right, the light will shine through the badge.

One of the most prominent users of reverse mounted LEDs is [TwinkleTwinkie], and now finally we have a writeup on the science of reverse mounted LEDs. There’s a lot to unpack here, so buckle up and prepare to burn the tips of your fingers on a soldering iron.

For truly reverse-mounted PCBs, there are two options. The first, and most expensive, are ‘reverse gullwing’ LEDs. These LEDs are just like normal LEDs, except the SMD pads are reversed, allowing you to mount it so the light shines into the PCB. These LEDs are expensive, rare (only three companies make them), and they don’t really give off a lot of light. The other solution to reverse-mounting a LED is simply taking a standard 1206 SMD LED and manually soldering it upside-down. This is not pick and place friendly, although I’m sure you could find an LED manufacture that would put LEDs in reels upside-down if you want.

Side view LEDs

The takeaway for reverse mount LEDs is pick two: good, fast, or cheap. Reverse gullwing LEDs are expensive, but can be pick and placed and provide sufficient illumination. Hand-soldered LEDs installed upside down are cheap, slow, but also good.

But there is another option. Side view LEDs are a thing, and they can be pick and placed. You can get them in every color, and even UV. [Twinkle] has experimented with side-view LEDs in place of reverse mounted LEDs, and the results are promising. By putting the side view LED next to part of a PCB without copper or soldermask, there is some light bleed through the PCB. It’s somewhat uneven, but with a hot melt glue diffusor, you can get a somewhat decent bar of light being emitted through a PCB.

If you want to put blinky on a PCB, you have a lot of options. If you want to put blinky on a PCB without having any visible light source, these are your options. This is the state of the art in artistic PCBs, and we’re so glad [Twinkle] could share it with us.

Solar Circuit Sculpture Pumms the Night Away

A word of warning: Google for the definition of the word “pummer” at your own risk. Rest assured that this beautiful solar-powered circuit sculpture fits the only definition of pummer that we care to deal with.

For the unfamiliar, a pummer is a device from the BEAM style of robotics, a sort of cyborg plant that absorbs solar energy during the day and turns it into a gently pulsating light that “pumms” away the dark hours.

[Mohit Bhoite]’s take on the pummer is an extraordinary model of a satellite executed mainly in brass rod. His attention to detail on the framework boggles our minds; we could work for days on a brass rod and never achieve the straight lines and perfect corners he did. The wings support two solar cells, while the hull of the satellite holds a dead-bugged 74HC240 octal buffer/line-driver chip and all the other pumm-enabling components. A one farad supercap – mounted to look like a dish antenna – is charged during the day and a single LED beacon blinks into the night.

No schematic is provided, but there are probably enough closeup shots to reverse engineer this, which actually sounds like a fun exercise. (Or you can cheat and fetch the PDF copy of the old Make magazine article that inspired him.)

Hats off to [Mohit] for a top-notch circuit sculpture. We’ve seen similarly detailed and well-executed sculptures from him before; something tells us this won’t be the last.

Thanks to [Varun Reddy] for the tip.

Custom Inflatables Are Only A Laser Beam Away

Carl Sagan one said “If you wish to make an apple pie from scratch, you must first invent the universe.” It might not be a very accurate description of the relative difficulty level of baking, but the logic is sound enough: there’s often a lot of ground work that needs to be to covered before you hit your ultimate goal. A perfect example of this principle is the inflatable raft that [ralph124c] hopes to eventually create; before he can set sail he has to perfect making balloon animals with his laser cutter.

In the long run, the raft will be constructed from sheets of TPU coated fabric that are fused together with a hot iron. But before he spends the time and money on building the real thing, he wants to do some scaled down tests to make sure his design works as expected. He makes a cryptic remark about learning the hard way that inflatables are prone to bouts of strange behavior, and out of an overabundance of caution we’ll just take his word for it.

He hoped to test his designs with the much cheaper LDPE film, but he found that the hot iron didn’t fuse it together in the way he was hoping. His mind turned to his 60 watt laser cutter, and wondered if the desired effect could be achieved by turning the power down as low as possible and quickly moving across the material.

His first attempts either blew right through the film or did absolutely nothing, but eventually he had the bright idea to move the laser farther from the LDPE. This put the beam out of focus, which not only expanded the area it would cover, but reduced the energy being delivered to the surface. With a bit more experimentation, he found he was able to neatly weld the pieces of material together. He even found that he could increase the power slightly to cut through the film without having to adjust the laser focus. With the ability to create complex inflatable shapes, perhaps [ralph124c] will create balloon version of Carl Sagan or an apple pie to celebrate.

Of course, this technology isn’t limited to birthday balloons and model rafts. The ability to quickly and easily produce custom inflatable shapes could be a huge boon to anyone working in soft robotics, and we’ve even seen similar concepts applied to haptic feedback systems.

[Thanks to Arthur for the tip.]

Components Cut in Half Reveal their Inner Beauty

We rarely take a moment to consider the beauty of the components we use in electronic designs. Too often they are simply commodities, bought in bulk on reels or in bags, stashed in a drawer until they’re needed, and then unceremoniously soldered to a board. Granted, little scraps of black plastic with silver leads don’t exactly deserve paeans sung to their great beauty – at least not until you cut them in half to reveal the beauty within.

We’ve seen a little of what [Tube Time] has accomplished here; recall this lapped-down surface-mount inductor that [electronupdate] did a while back. The current work is more extensive and probably somewhat easier to accomplish because [TubeTime] focused mainly on larger through-hole components such as resistors and capacitors. It’s not clear how the sections were created, but it is clear that extreme care was taken to lap down the components with enough precision that the inner structures are clearly visible, and indeed, carefully enough that some, most notably the LED, still actually work. For our money, though, the best looking cross-sections are the capacitors, especially the electrolytic, for which [Tube Time] thoughtfully provides both radial and axial sections. The little inductor is pretty cool too. Some of the component diagrams are annotated, too, which makes for fascinating reading.

Honestly, we could look at stuff like this all day.

Thanks to [Stuart Rogers] for the tip.

[Caleb Kraft] Brings us the Moon, on a Budget

As you might expect from one of our most illustrious alumni, [Caleb Kraft] is a rather creative fellow. Over the years he’s created some absolutely phenomenal projects using CNC routers, 3D printers, laser cutters, and all the other cool toys the modern hacker has access to. But for his latest project, a celebration of the full Moon, he challenged himself to go low-tech. The Moon is something that anyone on Earth can look up and enjoy, so it seemed only fitting that this project should be as accessible to others as possible.

[Caleb] started this project by looking for high-resolution images of the Moon, which was easy enough. He was even able to find sign shops that were more than happy to print a giant version for him. Unfortunately, the prices he was quoted were equally gargantuan. To really be something that anyone could do, this project needed to not only be easy, but as affordable as possible. But where do you get a giant picture of the Moon for cheap?

He eventually found a source for Moon shower curtains (we told you he was creative), which fit the bill perfectly. [Caleb] says they aren’t nearly as detailed as the original images he found, but unless you’ve got your face pressed up against it you’ll never notice anyway. To make the round frame, he used PEX tubing from the hardware store and simply stapled the curtain directly to the soft plastic. The hardest part of the whole project is arguably getting the curtain flat and taut on the PEX ring.

Technically you could stop now and have a pretty slick piece of art to hang on your wall, but [Caleb] took the idea a bit farther and put a strip of RGB LEDs along the inside of the ring. The shower curtain material does a decent enough job of diffusing the light of the LEDs to make it look pretty good, though there’s certainly some room for improvement if you want to get a more even effect over the entire surface. While you’re at it, you might as well add in some additional electronics so the lighting matches the current phase of the real-life Moon.

On the other hand, if you’re willing to settle for a far more diminutive version of Luna and don’t mind using those highfalutin hacker tools that [Caleb] decided to avoid for the good of mankind, we’ve got a project you might be interested in.

Continue reading “[Caleb Kraft] Brings us the Moon, on a Budget”

Social Media Jacket Puts Your Likes On Your Sleeve

The great irony of the social media revolution is that it’s not very social at all. Users browse through people’s pictures in the middle of the night while laying in bed, and tap out their approval with all the emotion of clearing their spam folder. Many boast of hundreds or thousands of “friends”, but if push came to shove, they probably couldn’t remember when they had last seen even a fraction of those people in the real world. Assuming they’ve even met them before in the first place. It’s the dystopian future we were all warned about, albeit a lot more colorful than we expected.

But what if we took social media tropes like “Likes” and “Follows”, and applied them to the real world? That’s precisely what [Tuang] set out to do with the “Social Touch Suit”, a piece of wearable technology which requires a person actually make physical contact with the wearer to perform social engagements. There’s even a hefty dose of RGB LEDs to recreate the flashy and colorful experience of today’s social media services.

Every social action requires that a specific and deliberate physical interaction be performed, which have largely been designed to mimic normal human contact. A pat on the shoulder signifies you want to follow the wearer, and adding them as a friend is as easy as giving a firm handshake. These interactions bring more weight to the decisions users make. For example, if somebody wants to remove you as a friend, they’ll need to muster up the courage to look you in the eye while they hit the button on your chest.

The jacket uses an Arduino to handle the low level functions, and a Raspberry Pi to not only provide the slick visuals of the touch screen display, but record video from the front and rear integrated cameras. That way you’ve even got video of the person who liked or disliked you. As you might expect, there’s a considerable energy requirement for this much hardware, but with a 5200 mAh LiPo battery in the pocket [Tuang] says she’s able to get a run time of 3 to 4 hours.

Considering how much gadgetry is packed into it, the whole thing looks remarkably wearable. We wouldn’t say it’s a practical piece of outerwear when fully decked out, but most of the electronic components can be removed if you feel like going low-key. [Tuang] also points out that for a garment to be functional it really needs to be washable as well, so being able to easily strip off the sensitive components was always an important part of the design in her mind.

The technology to sensors wearable and flexible is still largely in its infancy, but we’ve very excited to see where it goes. If projects like these inspire you, be sure to check out the presentation [Kitty Yeung] gave at the Hackaday Supercon where she talks about her vision for bespoke wearable technology. Continue reading “Social Media Jacket Puts Your Likes On Your Sleeve”