Utterly Precise Light Painting, Thanks To CNC And Stop Motion

May 4, 2019 by Donald Papp 13 Comments

Light painting is the process of moving a light while taking a long-exposure photograph, which creates a sort of drawing from the path of the light source. It’s been done in one way or another since at least the early-to-mid 1900s, but modern hardware and methods have allowed for all kinds of new spins on this old idea. [Josh Sheldon] demonstrates just how true this is with the light painting he did for a gum ad, showing what’s possible with a single multicolor LED under CNC control combined with stop-motion animation techniques. The rest of the magic comes from the software. [Josh] designs the animations in Blender, and the paths are then exported and used as the instructions for his self-made Light Painting Machine. The machine therefore recreates the original animation with lights and camera and not a single computer-generated graphic.

[Josh] is no stranger to light painting in this way. We’ve seen his fantastic machine at work before and we’re glad he shared the details behind his latest work. Embedded below is a concise video that shows the whole process, but if you’re in a hurry and just want to see the end product, here’s a shortcut to the results.

For those of you who would like to know more, there are plenty of details on [Josh]’s Light Painting Machine on GitHub along with a more in-depth description of the workflow and software, so check it out.

Continue reading “Utterly Precise Light Painting, Thanks To CNC And Stop Motion” →

3D Printing With Multiple Soluble Filaments

April 28, 2019 by Tom Nardi 12 Comments

Complex 3D-printed designs often require the use of an automatically generated support structure around them for stability. While this enables some truly incredible results, it adds considerable time and cost to the printing process. Plus there’s the painstaking process of removing all the support material without damaging the object itself. If you’ve got a suitably high-end 3D printer, one solution to this problem is doing the supports in a water soluble filament; just toss the print into a bath and wait for the support to dissolve away.

But what if you’re trying to print something that’s complex and also needs to be soluble? That’s precisely what [Jacob Blitzer] has been experimenting with recently. The trick is finding two filaments that can be printed at the same time but are dissolved with two different solutions. His experimentation has proved it’s possible to do with consumer-level hardware, but it isn’t easy and it’s definitely not cheap.

You might be wondering what the possible application for this technique is. For [Jacob], he wanted to be able to print hollow molds in complex geometric shapes that would ultimately be filled with concrete. The molds required extensive internal supports that would have been all but impossible to remove if they weren’t printed in a soluble filament. But he also wanted to be able to dissolve the mold once the concrete inside had cured. So he needed one easy to dissolve filament for the supports, and a harder to dissolve one for the actual mold.

For the mold itself, [Jacob] went with High Impact Polystyrene (HIPS) which can be dissolved with an industrial degreaser called Limonene. It’s expensive, and rather nasty to work with, but it does an excellent job of eating away the HIPS so that’s one problem solved. Finding a water-soluble filament for the supports that could be printed at similar temperatures to the HIPS took months of research, but eventually he found one called HyroFill that fit the bill. Unfortunately, it costs an eye-watering $175 USD per kilogram.

So you have the filaments, but what can actually print them at the same time? Multi-material 3D printing is a tricky topic, and there’s a few different approaches that have been developed over the years. In the end, [Jacob] opted to go with the FORMBOT T-Rex that uses the old-school method of having two individual hotends and extruders. It’s the simplest method conceptually, but calibrating such a machine is notoriously difficult. Running two exotic and temperamental filaments at the same time certainly doesn’t help matters.

After all the time, money, and effort put into the project (he also had to write the software that would create the 3D models in the first place) [Jacob] says he’s not exactly thrilled with the results. He’s produced some undeniably stunning pieces, but the failure rate is very high. Still, it’s fascinating research that appears to be the first of its kind, so we’re glad that he’s shared it for the benefit of the community and look forward to seeing where it goes from here.

Here’s A Tesla Coil You Can Wear

April 18, 2019 by Brian Benchoff 3 Comments

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

April 17, 2019 by Brian Benchoff 17 Comments

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.

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

April 4, 2019 by Dan Maloney 17 Comments

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

April 2, 2019 by Tom Nardi 26 Comments

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

April 2, 2019 by Dan Maloney 7 Comments

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.