Improving Exposure On A Masked SLA Printer

It’s taken longer than some might have thought, but we’re finally at the point where you can pick up an SLA 3D printer for a few hundred bucks. These machines, which use light to cure a resin, are capable of far higher resolution than their more common FDM counterparts, though they do bring along their own unique issues and annoyances. Especially on the lower end of the price spectrum.

[FlorianH] recently picked up the $380 SparkMaker FHD, and while he’s happy with the printer overall, he’s identified a rather annoying design flaw. It seems that the upgraded UV backlight in the FHD version of the SparkMaker produces somewhat irregular light, which in turn manifests itself as artefacts on the final print. Due to hot spots on the panel, large objects printed on the SparkMaker show fairly obvious scarring.

Now you might expect the fix for this problem to be in the hardware, but that’s not the way he’s taken it. These printers use an LCD panel to block off areas of the UV backlight, thereby controlling how much of the resin is exposed. This is technique is officially known as “masked SLA”, and is the technology used in most of these new entry level resin printers.

As luck would have it, the SparkMaker FHD allows showing various levels of grayscale on the LCD rather than a simple binary value for each pixel. At least in theory, this allows [FlorianH] to compensate for the irregular backlight by adjusting how much the UV is attenuated by the LCD panel. He’s focusing on the printer he personally owns, but the idea should work on any masked SLA printer that accepts grayscale values.

The first step was to map the backlight, which [FlorianH] did by soaking thin pieces of paper in a UV reactant chemical, and draping them over the backlight. He then photographed the illumination pattern, and came up with some OpenCV code that takes this images and uses the light intensity data to compensate for the local UV brightness underneath the sliced model.

So far, this method has allowed [FlorianH] to noticeably reduce the scarring, but he thinks it’s still possible to do better. He’s released the code for this backlight compensation script, and welcomes anyone who might wish to take a look at see how it could be improved.

An uneven backlight is just one of the potential new headaches these low-cost “masked” SLA printers give you. While they’re certainly very compelling, you should understand what you’re getting into before you pull the trigger on one.

LCD Panel Lamp Shade Makes For Eye-Catching Lighting

At first sight, [Kyle]’s Elroy lamp is simply an attractive piece of modern-styled interior furnishing; its clean lines, wood grain, and contemporary patterning being an asset to the room. But when he pulls out his phone, things change. Because this lamp hides a secret: at its heart may be a standard LED bulb, but the shade conceals four LCD screens driven by an Nvidia Jetson. These can be controlled through a web app to display a variety of textures, completing the effect.

This is not however simply a set of laptop screens bolted to a lampshade. The screens started life in laptops sure enough, but have since had their reflective backing removed to create a transparent LCD panel. Then an appropriate diffuser had to be found, which after much experimentation became a composite including more than one textured paper. Finally the whole was enclosed in an attractive wooden lamp frame and became part of the furniture. We like it, both as an aesthetically pleasing lamp and as a genuine departure from the norm.

This isn’t the first eye-catching lampshade we’ve brought you, but it’s certainly raised the bar. You can see it in action in the video below the break.

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Amstrad Portable Gets A Modern LCD Transplant

Playing classic games on the real hardware is an experience many of us enjoy, but sometimes the hardware is just a bit too retro for modern sensibilities. A case in point is the miserable monochrome LCD that was originally installed in the Amstrad PPC640 portable 8086 PC that [Drygol] recently picked up. He decided that his portable Amstrad sessions would be far more enjoyable if he swapped it out for a display that didn’t have 30+ years on the clock.

To quell the complaints of any of the vintage hardware aficionados out there, it’s worth mentioning that the original LCD was actually damaged and needed to be replaced anyway. Granted [Drygol] could have tried to find a contemporary panel to replace it with, but looking at the incredible before and after shots of the modded PPC640, it’s hard to argue he didn’t make the right decision by throwing a modern display into the otherwise largely original computer.

Getting the new LCD’s PCB ready for installation.

[Drygol] says he picked up a cheap 4:3 LCD TV on eBay, and as luck would have it, found that the new panel dropped perfectly into the original frame. Getting it buttoned back up required the removal of the RF can and all the female connections on the TV’s PCB, plus he had to cut some holes in the back of the display enclosure to mount the LCD’s controls, but overall it looks very stock.

Of course, getting the new LCD display in the original frame was only half the battle, it still needs to be connected up to the computer somehow. To get everyone playing nicely with each other, [Drygol] is using a commercially available MDA/CGA/EGA to VGA converter that is installed where the batteries would have gone originally. Wired to the PPC640’s external monitor connector, it allows him to drive the new display without having to use the original LCD interface.

[Drygol] has made something of a name for himself by performing some of the most impressive restorations and modifications of retro hardware in recent memory. From the unbelievable work that went into repairing a smashed Atari 800XL case to his gorgeous custom Amiga A500, his projects are sure to please the retro hardware lovers in the audience.

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Multimeter Display Perked Up With Nixies, LEDs, And Neon Tubes

Just because something is newer than something else doesn’t automatically make it better. Of course the opposite is also true, but when it comes to displays on bench multimeters, a fancy LCD display is no guarantee of legibility. Take the Hewlett Packard HP 3478A multimeter; the stock transflective display with its 14-segment characters is so hard to read that people usually have to add a backlight to use it.

That wasn’t good enough for [cyclotronboy], though, who chose to completely replace the stock 3478A display with Nixie tubes. He noticed that with a little modification, six IN-17 tubes just fit in the window vacated by the LCD. He sniffed out the serial data stream going to the display with a collection of XOR gates and flip-flops, which let him write the code for a PIC18F4550. The finished display adds a trio of rectangular LEDs for the + and – indicators, and an HDLO-1414 four-character alphanumeric display to indicate units and the like. And the decimal points? Tiny neon bulbs. It already looks miles better than the stock display, and with the addition of a red filter, it should look even better.

If you’re stuck with a lame LCD multimeter but Nixies don’t quite do it for you, worry not – an LED conversion is possible too.

The Future’s So Bright, I Gotta Wear LCDs

Whether it was rays from the Sun that made a 150 million kilometer trip just to ruin your day or somebody’s unreasonably bright aftermarket headlights, at some point or another we’ve all experienced the discomfort of bright spots in our eyes. But short of wearing welder’s goggles all the time, what can we do? Luckily for us, [Nick Bild] has come up with a solution. Sort of.

Modifying the LCD so it can be seen through.

By adding LCDs to a pair of standard sunglasses, [Nick] has created something he’s calling “Light Brakes”. The idea is that the LCDs, having their backings removed, can essentially be used as programmable shutters to block out a specific part of the image that’s passing through them. With the addition of a Raspberry Pi and a camera, the Light Brakes can identify an unusually bright source of light and block it from the wearer’s vision by drawing a sufficiently large blob on the LCDs.

At least, that’s the idea. As you can see in the video after the break, the LCDs ability to block out a moving source of light is somewhat debatable. It’s also unclear what, if any, effect the “blocking” would have on UV, so you definitely shouldn’t try looking at the sun with a pair of these.

That said, a refined version of the concept could have some very interesting applications. For instance, imagine a pair of glasses that could actively block out advertisements or other unpleasant images from your field of vision. If this all sounds a bit like something out of an episode of Black Mirror, that’s because it is.

Attentive readers may have noticed that this isn’t the first time these fashionable frames have graced the pages of Hackaday. Over the summer they were used in a very interesting field of view home automation project that [Nick] was working on. This also isn’t the first time he’s stuck a pair of small LCDs in front of his eyes in the name of progress. We’re starting to identify something of a trend here, though we certainly aren’t complaining.

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[Ben Krasnow] Looks Inside Film Camera Date Stamping

Honestly, we never wondered how those old film cameras used to put the date stamp in the lower right-hand corner of the frame. Luckily, [Ben Krasnow] does not suffer from this deplorable lack of curiosity, and his video teardown of a date-stamping film camera back (embedded below) not only answers the question, but provides a useful lesson in value engineering.

For the likely fair fraction of the audience who has never taken a photo on film before, cheap 35-mm cameras were once a big thing. They were really all one had for family snapshots and the like unless you wanted to invest in single-lens reflex cameras and all the lenses and accessories. They were miles better than earlier cartridge cameras like the 110 or – shudder – Disc film, and the cameras started getting some neat electronic features too. One was the little red-orange date stamp, which from the color we – and [Ben] assumed was some sort of LED pressed up against the film, but it ends up being much cooler than that.

Digging into the back of an old camera, [Ben] found that there’s actually a tiny projector that uses a mirror to fold the optical path between the film and a grain-of-wheat incandescent bulb. An LCD filter sits in the optical path, but because it’s not exactly on the plane of the film, it actually has to project the image onto the film. The incandescent bulb acts as a point source and the mirror makes the optical path long enough that the date stamp image appears sharp on the film. It’s cheap, readily adapted to other cameras, and reliable.

Teardowns like this aren’t fodder for [Ben]’s usual video fare, which tends more toward homemade CT scanners and Apollo-grade electroluminescent displays, but this was informative and interesting, too.

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Hackaday Links: October 6, 2019

“If you or someone you love has been exposed to questionable quality electrolytic capacitors, you could be entitled to financial compensation.” Perhaps that’s not exactly the pitch behind this class action lawsuit against capacitor manufacturers, but it might as well be. The suit claims that the defendants, a group of capacitor manufacturers that includes Nichicon, Matsuo, ELNA, and Panasonic, “engaged in an unlawful conspiracy to fix, raise, maintain, or stabilize the prices of Capacitors.” Translation: if you bought capacitors between 2002 and 2014 from a distributor, you paid too much for them. The suit aims to recover a bunch of money from the defendants and divide it up between all the class members, so make sure you go back through all your receipts from Mouser and DigiKey over the last 17 years so you can file a claim that could be worth several dozen cents.

When are people going to learn that posting pictures of their illegal activities online is an Official Bad Idea? One SpaceX fan earned a night in jail after posting selfies he took with Starhopper, the SpaceX test article currently residing at Elon Musk’s would-be spaceport at Boca Chica, Texas. JB Wagoner, a SpaceX super-fan, made the pilgrimage from California to Texas — in his Tesla of course — to see the recent Starship Mark 1 unveiling, and decided to take a side trip to see the Starhopper. He parked at a beach, climbed a dune, and was able to walk right up to Starhopper and go selfie-crazy. After posting the pictures on Facebook, he was arrested, interviewed by Homeland Security, charged with criminal trespass, and thrown in a cell overnight. Wagoner has since been bonded out, but the charges might not stick, since Texas trespassing law requires clear signage or verbal notification of trespass, neither of which Wagoner encountered. SpaceX had even let the fence between the beach and the Starhopper collapse, so Wagoner seems to have had no way of knowing he was trespassing. Still, posting the pictures online was probably asking for trouble.

As satire and dark comedy, the 1987 cyberpunk classic RoboCop can’t be beat. But it also managed to accurately foreshadow a lot of what was to come in the world in terms of technology. No, we don’t have cyborg law enforcement — yet — but we do have something predicted by one throwaway scene: robotic realtors. In the movie, kiosks were set up around Murphy’s old house to extol the various virtues of living there, which ended up triggering the cyborg and starting the film’s climactic rampage. The real-life robotic realtor is a little more flexible, more like a telepresence robot — described aptly as “a Segway with an iPad on top.” The robotic realtor is not autonomous; it only lets a remote realtor interact with potential homebuyers without having to travel to multiple homes. It seems a little gimmicky to us, but the robots are reported to have made 25 sales in their first year on the job.

We’ve been seeing a lot of cheap resin printers these days, enough to make us want to jump into the market and start playing with them. But the cheap ones are all cheap for the same reason — they’re so dang small! They all use LCD screens from phones to mask off the UV light used to cure the resin, and the resulting print volume is tiny. Clem Mayer from MayerMakes has bigger ideas, though: he wants to make a giant resin printer using an LCD monitor as the mask. It’s not as simple as using a bigger screen, though; the film used between the screen and the resin, a fluoropolymer film called FEP, gets deformed when used on larger screens. So Clem is looking at a new built-plate interface that floats the resin on a layer of denser, immiscible liquid. It’s an interesting idea that is still clearly in the proof-of-concept phase, but we look forward to seeing what progress Clem makes.