Matrix Of Resistors Forms The Hot Hands Behind This Thermochromic Analog Clock

May 24, 2020 by Dan Maloney 21 Comments

If you’re going to ditch work, you might as well go big. A 1,024-pixel thermochromic analog clock is probably on the high side of what most people would try, but apparently [Daniel Valuch] really didn’t want to go to work that day.

The idea here is simple: heat up a resistor by putting some current through it, lay a bit of thermochromic film over it, and you’ve got one pixel. The next part was not so simple: expanding that single pixel to a 32 by 32 matrix.

To make each pixel square-ish, [Daniel] chose to pair up the 220-ohm SMD resistors for a whopping 2,048 components. Adding to the complexity was the choice to drive them with a 1,024-bit shift register made from discrete 74LVC1G175 flip flops. With the Arduino Nano and all the other support components, that’s over 3,000 devices with the potential to draw 50 amps, were someone to be foolish or unlucky enough to turn on every pixel at once. Luckily, [Daniel] chose to emulate an analog clock here; that led to additional problems, like dealing with cool-down lag in the thermochromic film when animating the hands, which had to be dealt with in software.

We’ve seen other thermochromic displays before, including recently with this temperature and humidity display. This one may not be the highest resolution display out there, but it’s big and bold and slightly dangerous, and that makes it a win in our book.

A VFD Wall Thermometer

December 28, 2019 by Tom Nardi 5 Comments

Want to build something using VFD tubes, but don’t need yet another clock project? In that case, this wall mounted temperature and humidity display created by [commanderkull] might be exactly what you’re looking for. With six IV-11 tubes, this display is a practical way to add some of that gorgeous blue-green glow to your home or office.

The USB powered display uses a XL6009 and an XL7015 to provide the 24 V and 1.8 V needed by the IV-11 tubes, respectively. Both of which can be disconnected with jumpers to shut down the tubes without powering off the entire device, a useful feature when programming and debugging the display’s ATmega328P microcontroller. Each tube is connected to the ATmega with an 74HC595 shift register and a UDN2981 driver. Temperature and humidity data is provided, perhaps unsurprisingly, by the exceptionally common DHT22 sensor.

If you are looking to build another clock with these style tubes, there’s certainly enough prior art out there to get you started. We’ve also seen faux VFDs that you could use for either project, just in case you aren’t looking to deal with the voltage requirements and relative rarity of the real thing.

Programmable Wrist Synth Pushes The Envelope

December 11, 2019 by Kristina Panos 7 Comments

Synths are a ton of fun no matter how good or bad they sound. Really, there are no bad-sounding ones, it’s just that some are more annoying to listen than others to if you’re not the one making the beep boops. [Clem] had built a tiny LDR-based synth into a watch case a few years back and took it to many a Maker Faire, where it delighted and annoyed until it ultimately broke.

Naturally, it was time to make a new version that’s more capable. Whereas the first one was Atari-punk-console-meets-light-Theremin, this one has a bunch of inputs and can be programmed on the fly to record and play back bendable tones. It’s driven by an Arduino MKR, and the inputs are managed by an impressively squash bug-wired shift register. [Clem] used beefy switches this time in the hopes that this one will last longer. We think the slide pots are a great touch, as are the candy-colored knobs printed in PMMA.

Our favorite part is that [Clem] took advantage of the random states the microcontroller pins are in when it’s first powered on. If you don’t want to program any notes, you can use the ones generated at boot and just play around with those. Be sure to check out the build video after the break.

We’ve seen our share of synths, but few as delicious-looking as KELPIE from this year’s Hackaday Prize.

Continue reading “Programmable Wrist Synth Pushes The Envelope” →

Chaining Together A 16×2 Bubble LED Display

December 10, 2019 by Tom Nardi 27 Comments

We’ve recently noticed an uptick of interest in so-called “bubble displays”: vintage alphanumeric LEDs which are probably best remembered as being used in watches and calculators before the LCD took over. Today they’re available as surplus or even salvage for literally pennies, but unfortunately they only provide four or five characters to work with. Or rather they did, until [sjm4306] built a board that chains them into a 16×2 array.

For the princely sum of 71 cents each, [sjm4306] picked up ten HPDL-1414 displays, each capable of showing four characters. He then designed a PCB that would accept eight of the displays at once, and even thought ahead to use headers so they could be pulled out and swapped as needed. Of course mounting them is only half the battle, you still need to drive the things.

Each display has its own dedicated driver chip on board, but trying to address each one individually would take far too many pins. So [sjm4306] opted to use a trio of 74HC595 shift registers, allowing him to toggle the three dozen pins necessary over SPI from a microcontroller. He’s even written up a little library and some example code that you can grab on the project’s Hackaday.io page.

Unfortunately, after all his hard work, tragedy struck. As these displays were a couple decades old given their date code, [sjm4306] thought he would clean them up with a bit of alcohol before their big video debut. But whatever plastic the clear panels are made of didn’t take kindly to the IPA, and they all shattered. They still work, but it’s definitely a quirk to keep in mind if you pick up some of these vintage displays to play with yourself.

In the past we’ve seen a much smaller PCB that allowed similar displays to more easily be interfaced with modern microcontrollers; perfect if you just want to bang out a few retro LED characters with a minimum of fuss.

Continue reading “Chaining Together A 16×2 Bubble LED Display” →

[Ben Krasnow] Makes A DSKY

May 19, 2019 by Dan Maloney 6 Comments

There are hundreds if not thousands of artifacts from the Apollo program scattered around the globe, some twisted wrecks at the bottom of the ocean, others lovingly preserved and sitting in museums or in the hands of private collectors. All of what’s left is pretty much pure unobtainium, so if you want something Apollo-like, you’re probably going to have to make it yourself.

[Ben Krasnow] took up the challenge to make an electroluminescent Apollo-era DSKY display from scratch, with outstanding results. The DSKY, or “display and keyboard”, was the user interface for the Apollo Guidance Computer, the purpose-built digital navigation system that got a total of 24 men there and back again. [Ben] says it took a long time to recreate the display, and we can see why. He needed to master quite a few skills, including screen printing to get the glass-panel display working. The panel is a sandwich of phosphorescent paint, a dielectric, and conductive ink. The ink is silkscreened on the back to form the characters, all applied to indium tin oxide (ITO) conductive glass. A PCB with the same pattern of character segments lays behind that, driving each segment with 300 volts or so through a trio of HV507 high-voltage shift registers. It’s an impressive bit of engineering and gives off a decidedly not-homebrew vibe.

In the video below, [Ben] goes into detail about the trials he experienced on the way to this amazing endpoint, not least of which was frying chip after chip due to ineffective protection diodes in the shift registers. That’s an epic debugging story that’s worth the price of admission all by itself. It’s not the only DSKY in town, of course – [Fran Blanche] has been working on one for a while too – but there’s just something about that blue glow that we really like.

Continue reading “[Ben Krasnow] Makes A DSKY” →

The Clickiest Game Of Tetris You’ll Ever Play, On A Flip-Dot

May 14, 2019 by Dan Maloney 12 Comments

Like many other classics it’s easy to come up with ways to ruin Tetris, but hard to think of anything that will make it better. Adding more clickiness is definitely one way to improve the game, and playing Tetris on a flip-dot display certainly manages to achieve that.

The surplus flip-dot display [sinowin] used for this version of Tetris is a bit of an odd bird that needed some reverse engineering to be put to work. The display is a 7 x 30 matrix with small dots, plus a tiny green LED for each dot. Those LEDs turned out to be quite useful for replicating the flashing effect used in the original game when a row of blocks was completed, and the sound of the dots being flipped provides audio feedback. The game runs on a Teensy through a custom driver board and uses a Playstation joystick for control. The video below, in perfectly acceptable vertical format, shows the game in action and really makes us want to build our own, perhaps with a larger and even clickier flip-dot display.

The best thing about Tetris is its simplicity: simple graphics, simple controls, and simple gameplay. It’s so simple it can be played anywhere, from a smartwatch to a business card and even on a transistor tester.

Continue reading “The Clickiest Game Of Tetris You’ll Ever Play, On A Flip-Dot” →

Old Nixie Display Rides Again As 3D-Printer Filament Meter

May 9, 2019 by Dan Maloney 9 Comments

We’re not sure about the name of this Nixie tube filament meter that [Scott M. Baker] built. He calls it a “filadometer”, perhaps a portmanteau of “filament” and “odometer”, in which case it makes sense. It may not flow trippingly from the tongue and we can’t come up with anything better, but whatever moniker you use it’s actually a pretty cool build.

The filadometer started life as something completely different and utterly typical for Nixie tube projects – a temperature and humidity gauge. [Scott] decided to recycle the eight-tube display to keep track of his Prusa, and in doing so he reveals a pretty remarkable degree of forethought in his design process. The original Nixie display has all the usual trappings – the driver chips, the shift registers, and the high voltage power supply. What stands out is the modularity of his design: the tube sockets and drivers live on a backplane PCB, with a Raspberry Pi and a separate HV supply board plugging into it. The original display had a Model B Pi, so there was plenty of room for a new Zero W. A new printed case and a little programming to capture the filament use from Octoprint is all it took to put this nifty little build back in action. The video below shows the details.

We’re always excited to see new videos from [Scott] because we learn so much from looking over his virtual shoulder. If you haven’t checked out his stuff, take a look at his homage to the 8″ floppy or his dual-port memory hack for retro gaming.

Continue reading “Old Nixie Display Rides Again As 3D-Printer Filament Meter” →