Candle Powered Lantern Isn’t As Silly As You Think

July 6, 2024 by Adam Fabio 30 Comments

[Gilles Messier] at the Our Own Devices YouTube channel recently took a look at an interesting device — an electric lantern powered by a candle. At first glance, this sounds completely absurd. Why use a candle to power LEDs when you can use the light from the candle itself? This gadget has a trick up its sleeve, though. It lets candle light out and uses the heat from the candle flame to generate power for the LEDs.

The small Peltier “solid-state heat pump” module in the lantern acts as a thermoelectric generator, converting heat from the candle into electricity for the LEDs. The genius of the device is how it handles the candle “exhaust”. A bimetallic disk in the chimney of the lantern closes when the air inside the device is hot. The Peltier device converts the heat differential to electricity, causing the air inside the lantern to cool. Meanwhile, the candle is beginning to starve for oxygen. Once the air cools down a bit, the disk bends, allowing stale smoke out, and fresh air in, allowing the candle to burn brightly again. Then the cycle repeats.

[Gilles] does a deep dive into the efficiency of the lantern, which is worth the price of admission alone. These lanterns are pretty expensive — but Peltier modules are well-known by hackers. We’re sure it won’t be too hard to knock together a cheap version at home.

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Baffle The Normies With This Binary Thermometer

June 8, 2024 by Dan Maloney 9 Comments

We think it’s OK to admit that when someone puts a binary display on a project, it’s just a thinly veiled excuse to get more blinkenlights into the world. That and it’s a way to flex a little on the normies; you’ve gone pretty far down the tech rabbit hole to quickly decipher something like this binary-display thermometer, after all.

Don’t get us wrong, we think those are both perfectly valid reasons for going binary. And all things considered, a binary display for a thermometer like [Clovis Fritzen]’s is much simpler to decode than, say, a clock. Plus, it seems a bit that this build was undertaken at least partially as an exercise in Charlieplexing, which [Clovis] uses to drive the six-bit LED display using only three lines of GPIO from the Digispark ATtiny85 board running the show.

The temperature sensor is a DHT11, whose output is read by the microcontroller before being converted to binary and sent to the six-bit display. The 64-degree range is perfect for displaying the full range of temperatures most of us would consider normal, although we’d find 63°C a touch torrid so maybe there’s a little too much resolution on the upper end of the scale. Then again, switching to Fahrenheit would shift it toward the hypothermia end of the scale, which isn’t helpful. And you can just forget about Kelvin.

Old Dot-Matrix Displays Give Up Their Serial Secrets

June 4, 2024 by Dan Maloney 11 Comments

If there’s one thing we like better around here than old, obscure displays, it’s old, obscure displays with no documentation that need a healthy dose of reverse engineering before they can be put to use. These Plessey dot-matrix displays are a perfect example of that.

We’re not sure where [Michael] scored these displays, but they look fantastic. Each 8-pin DIP has two 5×7-matrix, high-visibility LED displays. They bear date codes from the late 80s under the part number, GPD340, but sadly, precious little data about them could be dredged up from the Interwebz. With 70 pixels and only six pins after accounting for power and ground, [Michael] figured there would be a serial protocol involved, but which pins?

He decided to brute-force the process of locating them, using a Pico to sequentially drive every combination while monitoring the current used with a current sensor. This paid off after only a few minutes, revealing that each character of the display has its own clock and data pins. The protocol is simple: pull the clock and data pins high then send 35 bits, which the display sorts out and lights the corresponding pixels. The video below shows a 12-character scrolling display in action.

Plessey made a lot of displays for military hardware, and these chunky little modules certainly have a martial air about them. Given that and the date code, these might have come from a Cold War-era bit of military hardware, like this Howitzer data display which sports another Plessey-made display.

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How To Cram 945 LEDs Into A Teeny Tiny Vegas-Style Sphere

May 31, 2024 by Donald Papp 18 Comments

[Carl Bugeja] finds the engineering behind the Las Vegas Sphere fascinating, and made a video all about the experience of designing and building a micro-sized desktop version. [Carl]’s version is about the size of a baseball and crams nearly a thousand RGB pixels across the surface.

A four-layer flexible PCB is the key to routing data and power to so many LEDs.

Putting that many addressable LEDs — even tiny 1 mm x 1 mm ones — across a rounded surface isn’t exactly trivial. [Carl]’s favored approach ended up relying on a flexible four-layer PCB and using clever design and math to lay out an unusual panel shape which covers a small 3D printed geodesic dome.

Much easier said that done, by the way. All kinds of things can and do go wrong, from an un-fixable short in the first version to adhesive and durability issues in later prototypes. In the end, however, it’s a success. Powered over USB-C, his mini “sphere” can display a variety of patterns and reactive emojis.

As elegant and impressive as the engineering is in this dense little display, [Carl] has some mixed feelings about the results. 945 individual pixels on such a small object is a lot, but it also ends up being fairly low-resolution in the end. It isn’t very good at displaying sharp lines or borders, so any familiar shapes (like circles or eyes) come out kind of ragged. It’s also expensive. The tiny LEDs may be only about 5 cents each, but when one needs nearly a thousand of them for one prototype that adds up quickly. The whole bill of materials comes out to roughly $250 USD after adding up the components, PCB, controller, and mechanical parts. It’s certainly a wildly different build than its distant cousin, the RGB cube.

Still, it’s an awfully slick little build. [Carl] doubts there’s much value in pursuing the idea further, but there are plenty of great images and clips from the build. Check out the video, embedded below.

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Put More Korry In Your Flight Sim Switches

May 3, 2024 by Dan Maloney 20 Comments

Never underestimate how far some flight simulator aficionados will go with their builds. No detail is too small, and every aspect of the look and feel has to accurately reflect the real cockpit. As a case in point, check out these very realistic Korry buttons that [Santi Luib III] built for an Airbus A320 simulator.

Now, you might never have heard of a “Korry button” before, but chances are you’ve seen them, at least in photos of commercial or military aircraft cockpits. Korry is a manufacturer of switches and annunciators for the avionics industry, and the name has become shorthand for similar switches. They’ve got a very particular look and feel and are built to extremely high standards, as one hopes that anything going into a plane would be. That makes the real switches very expensive, far more so than even the most dedicated homebrew sim builder would be comfortable with.

That’s where [Santi] comes in. His replica Korry buttons are built from off-the-shelf parts like LEDs and switches mounted to custom PCBs. The PCB was designed for either momentary or latching switches, and can support multiple LEDs in different colors. The assembled PCBs snap into 3D printed enclosures with dividers to keep light from bleeding through from one legend to the other.

The lenses are laser-cut translucent acrylic painted with urethane paint before the legends are engraved with a laser. The attention to detail on the labels is impressive. [Santi]’s process, which includes multiple coats of sealers, gets them looking just right. Even the LEDs are carefully selected: blue LEDs are too bright and aren’t quite the proper shade, so [Santi] uses white LEDs that are dimmed down with a bigger resistor and a light blue photographic gel to get the tint just right.

These buttons are just beautiful, and seeing a panel full of them with the proper back-lighting must be pretty thrilling. If civil aviation isn’t your thing, check out this A-10 “Warthog” cockpit sim, and the cool switches needed to make it just right.

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Boneblocker Is A Big LED Wall That Rocks

April 28, 2024 by Lewin Day 3 Comments

[Nick Lombardy] took on a job almost every maker imagines themselves doing at some point. He built a giant LED wall and he did a damn fine job of it, too. Introducing BoneBlocker.

BoneBlocker is an 8 x 14 wall of glass blocks that lives at a bar called The Boneyard. Each block was given a length of WS2812B LED strip. 30 LED/meter strips were chosen, as initial maths on the 60 LED/meter strips indicated the whole wall would end up drawing 1.5 kW. Discretion, and all that.

The whole display is run from a WT32-ETH01 board, which is a fast ESP32-based module that has onboard Ethernet to boot. [Nick] used the WLED library as he’d seen others doing great things with it, performance-wise. He ended up using one board per column to keep things fast, but he reckons this was also probably a little bit of overkill.

His article steps through the construction of the wall, the electronics, and the software required to get some games working on the display. The final result is quite something. Perhaps the best bit is his explanation of the custom controller he built for the game. Dig into it, you won’t be disappointed.

In particular, we love how the glass blocks elevate this display to a higher aesthetic level. We’ve seen other great projects tread this same route, too. Video after the break.

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DIY Electronics Plus Woodworking Equal Custom Lamp

April 24, 2024 by Inderpreet Singh 5 Comments

There is something about wooden crafts that when combined with electronics, have a mesmerizing effect on the visual senses. The Gesture Controlled DNA Wooden Desk Lamp by [Timber Rough] is a bit of both with a nice desk piece that’s well documented for anyone who wants to build their own.

Construction starts with a laser cutter being employed to add kerfs, such that the final strips can be bent along a frame tube to form the outer backbone of the DNA helix structure. Add to the mix some tung oil, carnauba wax, and some glue — along with skill and patience — and you get the distinct shape of sugar-phosphate backbone.

The electronics include an ESP8266 with the PAJ7620 gesture sensor that controls two WS2812B RGB LED Strips. The sensor in question is very capable, and comes with the ability to recognize nine human hand gestures along with proximity which makes it apt for this application. The sensor is mounted atop the structure with the LEDs twisting down the frame to the base where the ESP8266 is tucked away. Tiny glass bottles are painted with acrylic spray varnish and then glued to the LEDs to form the base pairs of the double helix. We thought that the varnish spray was a clever idea to make light diffusers that are quick and cheap for most DIYers.

We previously covered how this particular gesture sensor can be used to control much more than a lamp if you seek more ideas in that realm.

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