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82 Articles

Have Yourself A Recursive Little Christmas: Ornament That Prints Ornaments

December 24, 2018 by 10 Comments

Sure there are the occasional functional Christmas tree ornaments; we had one that plugged into the lights and was supposed to sound like a bird gently trilling its song, but was in fact so eardrum-piercing that we were forbidden from using it. But in general, ornaments are just supposed to be for looks, right? Not so fast — this 3D-printed ornament has a 3D-printer inside that prints other ornaments. One day it might just be the must-have in functional Christmas decor.

Given that [Sean Hodgins] had only a few days to work on this tree-dwelling 3D-printer, the questionable print quality and tiny print volume can be overlooked. But the fact that he got this working at all is quite a feat. We were initially surprised that he chose to build a stereolithography (SLA) printer rather than the more common fused deposition modeling (FDM) printer, but it makes sense. SLA only requires movement in the Z-axis, provided in this case by the guts of an old DVD drive. The build platform moves in and out of a tiny resin tank, the base of which has a small LCD screen whose backlight has been replaced by a bunch of UV LEDs. A Feather M0 controls the build stage height and displays pre-sliced bitmaps on the LCD, curing the resin in the tank a slice at a time.

Results were mixed, with the tiny snowflake being the best of the bunch. For a rush job, though, and one that competed with collaborating on a package-theft deterring glitter-bomb, it’s pretty impressive. Here’s hoping that this turns into a full-sized SLA build like [Sean] promises.

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Seeing Like Bees With Ultraviolet Photography

December 19, 2018 by 14 Comments

When it comes to seeing in strange spectrums, David Prutchi is the guy you want to talk to. He’s taken pictures of rocks under long, medium and short UV light, he’s added thermal imaging to consumer cameras, and he’s made cameras see polarization. There’s a lot more to the world than what the rods and cones on your retina can see, and David is one of the best at revealing it. For this year’s talk at the Hackaday Superconference, David is talking about DIY Ultraviolet Photography. It’s how bees see, and it’s the bees knees.

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Simple, Low-Cost Rig Lets The Budding Biohacker Run DNA Gels

December 1, 2018 by 12 Comments

We all the know the basic components for building out an electronics lab: breadboards, bench power supply, a selection of components, a multimeter, and maybe an oscilloscope. But what exactly do you need when you’re setting up a biohacking lab?

That’s the question that [Justin] from The Thought Emporium is trying to answer with a series of videos where he does exactly that – build a molecular biology lab from scratch. In the current installment, [Justin] covers the basics of agarose gel electrophoresis, arguably the fundamental skill for aspiring bio-geeks. Electrophoresis is simply using an electric field to separate a population of macromolecules, like nucleic acids and proteins, based on their sizes. [Justin] covers the basics, from building a rig for running agarose gels to pouring the gels to doing the actual separation and documenting the results. Commercial grade gear for the job is priced to squeeze the most money out of a grant as possible, but his stuff is built on the cheap, from dollar-store drawer organizers and other odd bits. It all works, and it saves a ton of money that can be put into the things that make more sense to buy, like fluorescent DNA stain for visualizing the bands; we’re heartened to see that the potent carcinogen ethidium bromide that we used back in the day is no longer used for this.

We’re really intrigued with [Justin]’s bio lab buildout, and it inspires us to do the same here. This and other videos in the series, like his small incubators built on the cheap, will go a long way to helping others get into biohacking.

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Persistence Of Phosphorescence Clock Displays YouTube Stats Too

April 5, 2018 by 21 Comments

Looking for an eye-catching and unique way to display the time and date? Want the flexibility to add other critical information, like the number of YouTube subs you’ve got? Care to be able to read it from half a block away, at least at night? Then this scrolling glow-in-the-dark dot-matrix display could be right up your alley.

Building on his previous Morse code transcriber using a similar display, [Jan Derogee] took the concept and went big. The idea is to cover a PVC pipe with phosphorescent tape and rotate it past a row of 100 UV LEDs. The LEDs are turned on as the glow-in-the-dark surface passes over them, charging up a row of spots. The display is built up to two rows of 16 characters by the time it rotates into view, and the effect seems to last for quite a while. An ESP8266 takes care of driving the display and fetching NTP time and YouTube stats.

We’ve seen “persistence of phosphorescence” clocks before, but not as good looking and legible as this one. We like the approach, and we can’t help but think of other uses for glow-in-the-dark displays.

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3D Printering: Print Smoothing Tests With UV Resin

March 8, 2018 by 16 Comments

Smoothing the layer lines out of filament-based 3D prints is a common desire, and there are various methods for doing it. Besides good old sanding, another method is to apply a liquid coating of some kind that fills in irregularities and creates a smooth surface. There’s even a product specifically for this purpose: XTC-3D by Smooth-on. However, I happened to have access to the syrup-thick UV resin from an SLA printer and it occurred to me to see whether I could smooth a 3D print by brushing the resin on, then curing it. I didn’t see any reason it shouldn’t work, and it might even bring its own advantages. Filament printers and resin-based printers don’t normally have anything to do with one another, but since I had access to both I decided to cross the streams a little.

The UV-curable resin I tested is Clear Standard resin from a Formlabs printer. Other UV resins should work similarly from what I understand, but I haven’t tested them.

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Not Your Typical POV Clock

February 7, 2018 by 23 Comments

Persistence of vision displays are fun, and a natural for clocks, but they’re getting a little Nixie-ish, aren’t they? There are only so many ways to rotate LEDs and light them up, after all. But here’s something a little different: a POP, or “persistence of phosphorescence” clock.

[Chris Mitchell] turned the POV model around for this clock and made the LEDs stationary, built into the tower that holds the slowly rotated display disk. Printed from glow-in-the-dark PLA, the disk gets charged by the strip of UV LEDs as it spins, leaving behind a ghostly dot matrix impression of the time. The disk rotates on a stepper, and the clock runs on a Nano with an RTC. The characters almost completely fade out by the time they get back to the “write head” again, making an interesting visual effect. Check it out in the video after the break.

Our only quibble is the choice to print the disk rather than cut it from sheet stock. Seems like there has to be commercially available phosphorescent plastic, or even the glow-in-the-dark paper used for this faux LED scrolling sign. But if you’ve got glowy PLA, why not use it?

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Improvising An EPROM Eraser

January 17, 2018 by 86 Comments

Back in the old days, when we were still twiddling bits with magnetized needles, changing the data on an EPROM wasn’t as simple as shoving it in a programmer. These memory chips were erased with UV light shining through a quartz window onto a silicon die. At the time, there were neat little blacklights in a box sold to erase these chips. There’s little need for these chip erasers now, so how do you erase and program a chip these days? Build your own chip eraser using components that would have blown minds back in the 70s.

[Charles] got his hands on an old 2764 EPROM for a project, but this chip had a problem — there was still data on it. Fortunately, old electronics are highly resistant to abuse, so he pulled out the obvious equipment to erase this chip, a 300 watt tanning lamp. This almost burnt down the house, and after a second round of erasing of six hours under the lamp, there were still unerased bits.

Our ability to generate UV light has improved dramatically over the last fifty years, and [Charles] remembered he had an assortment of LEDs, including a few tiny 5mW UV LEDs. Can five milliwatts do what three hundred watts couldn’t? Yes; the LED had the right frequency to flip a bit, and erasing an EPROM is a function of intensity and time. All you really need to do is shine a LED onto a chip for a few hours.

With this vintage chip erased, [Charles] slapped together an EPROM programmer — with a programming voltage of 21V — out of an ATMega and a bench power supply. It eventually worked, allowing [Charles]’ project, a vintage liquid crystal display, to have the right data using vintage-correct parts.