Pushing The Limits Of A 16×2 LCD With Bad Apple!!

June 14, 2022 by Dan Maloney 20 Comments

While low-contrast, blue-on-slightly-less-blue 16-character by 2-line LCDs are extremely popular, they really are made specifically for alphanumeric use. They do an admirable job of displaying a few characters, but they don’t exactly spring to mind as a display for non-character purposes. But displaying video on a 16×2 LCD is possible, as long as you’re willing to stretch the definition of “video” a bit and use some imagination while watching.

Normally, a 16×2 display can only display a single character in each spot, chosen from a fixed character set. But [arduinocelantano] was able to leverage the eight custom character slots the display allows to build up images from arbitrary 5×8 pixel bitmaps. After using ffmpeg to scale the original video to a viewport of eight characters, a Python program was used to turn every frame of the scaled video into code to generate the custom bitmaps for each chunk of the viewport. Even with the low refresh rate of the display and the shrunken frame size, the result is a recognizable video, helped no doubt by the choice of the shadow-puppet Bad Apple!! video. Check it out after the break to see how it looks.

We saw a similar rendering of the same video on LCD a while back; that effort was amazing in that it was an EEPROM-only implementation, along with a somewhat bigger LCD with better contrast. That project served as inspiration for [arduinocelantano]’s build here, which in some ways we think looks a bit better — perhaps it’s the inverted pixels. Either way, hats off to both builders for pushing past the normal constraints and teaching us something interesting.

Continue reading “Pushing The Limits Of A 16×2 LCD With Bad Apple!!“ →

Bug Zapper Counts And Serenades Its Victims

June 11, 2022 by Sven Gregori 10 Comments

Not many creatures are as universally despised as mosquitoes, whether it’s the harmless kind that, at worst, makes you miss winter, or the more serious ones that can be a real threat to your health. A satisfying way to deal with them is to send them off with a bang using one of those racket-shaped high voltage metal mesh bug zappers. [lmu34] saw big potential for some additional gamification here, and decided to equip his zapper with a kill counter and matching sound effects.

The initial thought was that there has to be a way to detect when a mosquito hits the mesh, and use that to trigger further events — in [lmu34]’s case play a sound file and increment a counter. After taking the zapper apart and doing a bit of research, he put theory into practice using a Digispark Pro board containing an ATtiny167, the DFPlayer module for playing a set of WAV files, and an ambitious four digit 7-segment display to keep track of the “score”. A new 3d-printed cover provided enough space to house all the components, including a charging circuit as he swapped the original two AAA batteries with a rechargeable one, which gave a bit more power for the display.

Of course, with these operation voltages, it would be difficult to detect activity on the high voltage side more than once, so [lmu34] went with current sensing instead. He distinguishes between two different levels here and maps them as normal kill and monster kill for the big zaps respectively, playing different sounds for each. Have a look at the video after the break for some quick demonstration.

All in all, this is a delightfully absurd modification that almost screams for an ESP32 to enable multiplayer mode as next iteration. But if chasing mosquitoes with low-tech gadgets isn’t for you, there’s always lasers and good old torture, although those can’t be repurposed to do some hardware fault injections during the winter months then.

Continue reading “Bug Zapper Counts And Serenades Its Victims” →

An Interesting Circular Stewart Platform

June 10, 2022 by Dave Rowntree 8 Comments

Stewart platforms are pretty neat, and not seen in the wild all that often, perhaps because there aren’t a vast number of hacker-friendly applications that need quite this many degrees of freedom within such a restricted movement range. Anyway, here’s an interesting implementation from the the curiously named [Circular-Base-Stewart-Platform] YouTube channel (no, we can’t find the designer’s actual name) with a series of videos from a few years ago, showing the construction and operation of such a beast. This is a very neat mechanism comprised of six geared motors on the end of arms, engaging with a large internal gear. The common end of each arm rides on the central shaft, each with its own bearing. With the addition of the usual six linkages, twelve ball joints, and a few brackets, a complete platform is realised.

This circular arrangement is so simple that we can’t believe we haven’t come across it before. One interesting deviation from the usual Stewart platform arrangement is the use of a central slip-ring connector to provide power, allowing the whole assembly to rotate continuously, in addition to the usual six degrees of freedom the mechanism allows. Control is courtesy of an Arduino Pro Mini, which drives the motors using a handful of Pololu TB6612 (PDF) dual H-bridge driver modules. Obviously, the sketch running on the Arduino will give the thing a fixed motion, but add in an additional data link over that central slip-ring setup (or maybe a wireless link), and it will be much more useful.

We recently saw another 6-DOF actuator design, using flexures, yet another ball-balancing hack, but if you want an actually useful Stewart platform application, checkout this pool-playing robot!

Continue reading “An Interesting Circular Stewart Platform” →

Unorthodox Toolbox Switcheroo: Barbecue!

June 8, 2022 by Sven Gregori 24 Comments

Despite all the progress in cooking methods over the past millennia, nothing can ever replace the primeval sensation of staring into the embers as your food slowly gets ready. Barbecues are the obvious choice to satisfy this cave nostalgia, and while size might matter in some cases, sometimes you just want the convenience of being able to take your grilling device to the beach, park, or just really anywhere but home. Other times you’re [Laura Kampf] and don’t want to use an old toolbox for storing tools.

It all started with one of those typical three-layer folded cantilever toolboxes that [Laura] really likes for their mechanical construction, but not so much from a usability point of view. Being someone with a knack for turning random stuff into barbecues, this was an intriguing enough device to take apart. After plenty of time spent grinding bolts and paint off, she cut out the tray bottoms to weld metal mesh pieces as grill grates in their place — but you can watch the whole progress in the video below then.

The folding mechanics play out really nicely here. Not only can you access the grill goods by moving them away from the burning coals that are placed in the center bottom part of the box, it also provides you with two different heat layers. The individual lids on each side add even more variety, and this might even work as portable little smoker.

We’ve seen [Laura]’s work a few times before already, and in case you haven’t, go check out her beer keg motorcycle side car, wheelbarrow bicycle trailer, or Zippo lighter turned drill bit storage box.

Continue reading “Unorthodox Toolbox Switcheroo: Barbecue!” →

3D-Printed Power Loom Shows How Complex Weaving Really Is

June 7, 2022 by Dan Maloney 35 Comments

The seemingly humble flying-shuttle loom, originally built to make the weaving of wide cloth faster and easier, stood at the threshold between the largely handcrafted world of the past and the automated world that followed. And judging by how much work went into this miniature 3D-printed power loom, not to mention how fussy it is, it’s a wonder that we’re not all still wearing homespun cloth.

Dealing with the warp and the weft of it all isn’t easy, as [Fraens] discovered with this build. The main idea with weaving is to raise alternate warp threads, which run with the length of the fabric, to create a virtual space, called the shed, through which a shuttle carrying the weft thread is passed. The weft thread is then pressed in place by a comb-like device called the reed, the heddles carrying the warp threads shift position, and the process is repeated.

[Fraens]’ version of the flying-shuttle loom is built mostly from 3D-printed parts, with a smattering of aluminum and acrylic. There are levers, shafts, and cams galore, not to mention the gears and sprockets that drive the mechanism via a 12-volt gear motor. The mechanism that moves the shuttle back and forth in the shed is particularly interesting; it uses cams to release the tension stored in elastic bands to flick the shuttle left and right. Shuttle timing is critical, as a few of the fails later in the video show. [Fraens] had to play with cam shape and lever arm length to get the timing right, not to mention having to resort to a chain drive to get enough torque to move the shuttle.

We’ve seen power looms before, but mainly those that operate at a somewhat more stately pace than this one. Hats off to [Fraens] for showing the true complexity involved in automating weaving.

Continue reading “3D-Printed Power Loom Shows How Complex Weaving Really Is” →

The Dangerously Delightful Homemade Rockets Of Thailand

June 4, 2022 by Dan Maloney 25 Comments

Every once in a while, we here at Hackaday stumble across something that doesn’t quite fit in with all the other amazing hacks we feature, but still seems like something that our dear readers need to see as soon as possible. This video of homemade rockets in Thailand is one of those things.

It comes to us from our friend [Leo Fernekes], who documents a form of amateur rocketry that makes the Estes rockets of our youth look pretty tame. It’s far easier to watch than it is to describe, but for a quick summary, the rockets are bamboo rings with a steel pipe across the diameter. The pipe is packed with homemade gunpowder and provided with nozzles that create both thrust and rotation. When ignited by torches touched to seriously sketchy primers, the rocket starts to spin up, eventually rising off the launch pad and screwing itself into the sky on a twisting column of gray smoke.

At three or four meters across, these are not small vehicles. Rather than letting a steel pipe plummet back to Earth from what looks like several hundred meters altitude, the rocketeers have devised a clever recovery system that deploys a parachute when the rocket motor finally melts through some plastic straps. The use of banana tree bark as a heat shield to protect the parachute is simple but effective; which is really the way you can describe the whole enterprise. [Leo] has another way to describe it: “Dangerously negligent madness,” with all due respect and affection, of course. It looks like a big deal, too — the air is obviously filled with the spirit of competition, not to mention the rotten-egg stench of gunpowder.

Should you try this at home? Probably not — we can think of dozens of reasons why this is a bad idea. Still, it’s amazing to watch, and seeing how much altitude these cobbled-up rockets manage to gain is truly amazing. Hats off to [Leo] for finding this for us.

Continue reading “The Dangerously Delightful Homemade Rockets Of Thailand” →

Practical Transistors: JFETs

June 2, 2022 by Al Williams 16 Comments

Transistors come in different flavors. Tubes used an electric field to regulate current flow, and researchers wanted to find something that worked the same way without the drawbacks like vacuum and filament voltages. However, what they first found — the bipolar transistor — doesn’t work the same way. It uses a small current to modulate a larger current, acting as a switch. What they were looking for was actually the FET — the field effect transistor. These come in two flavors. One uses a gate separated from the channel by a thin layer of oxide (MOSFETs), and the other — a junction or JFET — uses the property of semiconductors to deplete or enhance carriers in the channel. [JohnAudioTech] takes a decidedly practical approach to JFETs in a recent video that you can watch below.

The idea for the FET is rather old, with patents appearing in 1925 and 1934, but there were no practical devices at either time. William Shockley tried and failed to make a working FET in 1947, the same year the first point-contact transistor appeared, which was invented while trying to create practical FETs. In 1948, the bipolar junction transistor hit the scene and changed everything. While there were a couple of working FETs created between 1945 and 1950, the first practical devices didn’t appear until 1953. They had problems, so interest waned in the technology while the industry focused on bipolar transistors. However, FETs eventually got better, boasting both very high input impedance and simplified biasing compared to bipolar technology.

Continue reading “Practical Transistors: JFETs” →