Improving Exposure On A Masked SLA Printer

November 12, 2019 by Tom Nardi 6 Comments

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 artifacts 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 he’s taken it in a different direction. 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.

Ambitious LED Cube Provides Endless Video Game Scrolling; Plays Castlevania

November 4, 2019 by Dan Maloney 12 Comments

LED cubes are all the rage right now, and rightly so given the amount of work that goes into them and the interesting things people find to do with them. Not content to make yet another position-sensitive display or an abstract design, though, [Greig Stewart] opted for something a bit more ambitious: an LED cube with a playable game of Castlevania.

As ambitious projects often do, this one required leveraging the previous art, some of which we’ve featured before. [Greig] pulled inspiration and information from cube builders like [polyfloyd], [Greg Davill], and [kbob] to put the six 64-LED matrix panels to work. Getting the structural elements figured out was an early stumbling block, but [Greig] pulled it off with 3D-printed brackets and a hinge that’s a work of art in itself; the whole thing looks like something the Borg would have built. The Raspberry Pi inside made a Gameboy emulator possible, and his first stab at it was to have six different games running at once, one on each panel. He settled on just one game, the classic side-scroller Castlevania, played on just four of the panels. Some wizardry was required to de-scroll the game so that the character walks around the cube rather than having the background scroll; you can check out the results in the clip below.

Currently, the cube sits on a lazy susan with a small motor controlling the swiveling in response to a foot control. [Greig] wants to put the motor under control of the game so that physical scrolling is synced with gameplay; we heartily endorse that plan and look forward to the results.

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Rise And Shine With This Japanese-Inspired Clock

November 3, 2019 by Tom Nardi 4 Comments

On the Hackaday.io page for his gorgeous “Sunrise Alarm Clock”, [The Big One] is quick to point out that his design is only inspired by Japanese lanterns, and does not use authentic materials or traditional woodworking techniques. Perhaps that’s an important fact to some, but we’ll just say that the materials used seem far less important when the end result looks this good.

Unfortunately [The Big One] hasn’t provided any interior shots of his clock, as it sounds like the aesthetics of the internal wiring isn’t quite up to the standard set by the outside of it. But he has provided a concise parts list, a wiring diagram, and source code, so we’ve got a pretty good idea of what’s under the hood.

The clock is powered by the uBBB 32u4, an ATMega32u4 development board that [The Big One] developed in conjunction with [Warren Janssens]. It uses the popular MAX7219 LED matrix for the display, and a DS3231 RTC module to help keep the time. There’s also a DFPlayer Mini module onboard that allows him to play whatever sound effects or music he wants when the alarm goes off.

Of course the star of the show is the LED strips which illuminate the shōji-style column. These have apparently been wrapped around a coffee can of all things, which not only serves as a convenient way of holding the strips, but [The Big One] says actually makes the speaker sound a bit better. Hey, whatever works.

This isn’t the first “lantern” clock to grace these pages, but compared to the high-tech presentation of previous projects, we can’t help but be impressed by the grace and elegance of this wooden masterpiece.

IR Hack Turns Kid’s Lamp Into Temp Display

November 2, 2019 by Jenny List 2 Comments

Sometimes a clever hack of an off-the-shelf product can come courtesy of its dismantling and hardware modification, but at other times the most elegant of hacks can be made without ever turning a screwdriver. [Brian Lough] was given the request by a friend to replicate a commercial child’s night light that changed colour with temperature, and his response was to use an off-the-shelf colour changing kids light unmodified, sending it temperature-related colour commands via its infra-red control.

His device is a spectacularly simple one hardware-wise using an off-the-shelf Wemos D2 Mini ESP8266 board running an Arduino bootloader, coupled with a BME280 temperature sensor, IR receiver, and transmitter. His video which we’ve placed below the break is a handy primer to anyone with an interest in infra-red reverse engineering, and we can see that there will be other projects that could be seeded by it. For those curious enough to look, it can be found on GitHub.

[Brian] has appeared here so many times, and is definitely worth a follow. One of his more recent builds featured another child’s toy augmented to make it something really special.

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An ESP32 Clock With A Transforming LED Matrix

October 29, 2019 by Tom Nardi 5 Comments

Over the years we’ve seen countless ways of displaying the current time, and judging by how many new clock projects that hit the tip line, it seems as though there’s no end in sight. Not that we’re complaining, of course. The latest entry into the pantheon of unusual timepieces is this ESP32-powered desk clock from [Alejandro Wurts] that features a folding LED matrix display.

The clock uses eight individual 8 x 8 LED arrays contained in a 3D printed enclosure that hinges in the middle. When opened up the clock has a usable resolution of 8 x 64, and when its folded onto itself the resolution becomes 16 x 32.

This variable physical resolution allows for alternate display modes. When the hardware detects that its been folded into the double-height arrangement, it goes into a so-called “Big Clock” mode that makes it easier to see the time from a distance. But while in single-height mode, there’s more horizontal real estate for adding the current temperature or other custom data. Eventually [Alejandro] wants to use MQTT to push messages to the display, but for now it just shows his name as a placeholder.

The key to the whole project is the hinged enclosure and the reed switch used to detect what position it’s currently in. Beyond that, there’s just an ESP32 an some clever code developed with the help of the MD_Parola library written for MAX7219 and MAX7221 LED matrix controllers. [Alejandro] has published the code for his clock, which should be helpful for anyone who’s suddenly decided that they also need a folding LED matrix in their life.

Now if the ESP32 LED matrix project you have in mind requires full color and high refresh rates, don’t worry, we’ve got a solution for that.
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The Basics Of Persistence Of Vision Projects

October 29, 2019 by Lewin Day 6 Comments

Persistence of Vision (POV) is a curious part of the human visual system. It’s the effect by which the perception of an image lingers after light has stopped entering the eye. It’s why a spinning propeller appears as a disc, and why a burning sparkler appears to leave a trail in the air. It’s also commonly used as a display technology, where a series of flashing LEDs can be used to create messages that appear to float in the air. POV displays are a popular microcontroller project, and today, we’ll explore the basic techniques and skills required in such builds.

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24 Hours Of Temperature Data At A Glance

October 25, 2019 by Tom Nardi 7 Comments

In an era where we can see the current temperature with just a glance at our smartphones, the classic “Time and Temp” gadget sitting on the desk doesn’t have quite the same appeal. The modern weather fanatic demands more data, which is where this gorgeous full-day temperature display from [Richard] comes in.

The display, built inside of a picture frame, shows the temperature recorded for every hour of the day. If the LED next to the corresponding hour is lit that means the value displayed is from the current day, otherwise it’s a holdover from the previous day’s recordings. This not only makes sure all 24 LED displays have something to show, but gives you an idea of where the temperature might be trending for the rest of the day. Naturally there’s also a display of the instantaneous temperature (indoor and outdoor), plus [Richard] even threw in the current wind speed for good measure.

In the video after the break, [Richard] briefly walks us through the construction of his “Thermo Logger”, which reveals among other things that the beautiful panel art is nothing more exotic than a printed piece of A4 paper. The video also features a 3D model of the inside of the device which appears to have been created through photogrammetry; perhaps one of the coolest pieces of project documentation we’ve ever seen. We’ll just throw this out there: if you want to ensure that your latest build makes the front page of Hackaday, pop off that back panel and make some decent quality 3D scans.

Given the final result, it should come as no surprise to find that this isn’t the first incredible weather display that [Richard] has built. We previously covered another weather monitoring creation of his that needed two seperate display devices to adequately display all the data it was collecting.

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