When it comes to building a neural network to simulate complex behavior, Arduino isn’t exactly the first platform that springs to mind. But when your goal is to model the behavior of an organism with only a handful of neurons, the constraints presented by an Arduino start to make sense.

It may be the most important non-segmented worm you’ve never heard of, but Caenorhabditis elegans, mercifully abbreviated C. elegans, is an important model organism for neurobiology, having had its entire nervous system mapped in 2012. [Nathan Griffith] used this “connectome” to simulate a subset of the diminutive nematode’s behaviors, specifically movements toward attractants and away from obstacles. Riding atop a small robot chassis, the Arduino sends signals to the motors when the model determines it’s time to fire the virtual worm’s muscles. An ultrasonic sensor stands in for the “nose touch” neurons of the real worm, and when the model is not busy avoiding a touch, it’s actively seeking something to eat using the “chemotaxis” behavior. The model is up on GitHub and [Nathan] hopes it provides an approachable platform for would-be neuroroboticists.

This isn’t the first time someone has modeled the nematode’s connectome in silico, but kudos to [Nathan] for accomplishing it within the constraints an Arduino presents.

Some people collect stamps, some collect barbed wire, and some people even collect little bits of silicon and plastic. But the charmingly named [videoschmideo] collects memories, mostly of his travels around the world with his wife. Trinkets and treasures are easy to keep track of, but he found that storing the audio clips he collects a bit more challenging. Until he built this audio memory chest, that is.

Granted, you might not be a collector of something as intangible as audio files, and even if you are, it seems like Google Drive or Dropbox might be the more sensible place to store them. But the sensible way isn’t always the best way, and we really like this idea. Starting with what looks like an old card catalog file — hands up if you’ve ever greedily eyed a defunct card catalog in a library and wondered if it would fit in your shop for parts storage — [videoschmideo] outfitted 16 drawers with sensors to detect when they’re opened. Two of the drawers were replaced by speaker grilles, and an SD card stores all the audio files. When a drawer is opened, a random clip from that memory is played while you look through the seashells, postcards, and what-have-yous. Extra points for using an old-school typewriter for the drawer labels, and for using old card catalog cards for the playlists.

This is a simple idea, but a powerful one, and we really like the execution here. This one manages to simultaneous put us in the mood for some world travel and a trip to a real library.

Not all of us have CNC machines, laser cutters and 3D printers, and I’ll bet most of us didn’t start out that well equipped. The low-cost drawing machine that [jegatheesan] made for his daughter reminds us that you can prototype, and then make a functioning mechanical Da Vinci with very basic materials and mostly hand tools. He also wrote his own drawing software, with an interface that has its own simplicity.

There really are a lot of things to like about [jegatheesan]’s project. He first works out the math himself by doing something the likes of which we’ve all enjoyed, digging out the old school trigonometry and algebra books for a refresher. Then he got started on his prototype, made using a cardboard tube for the main support and straws and safety pins for the drawing arms. He already had a motor shield for his Arduino but it supported only 2 servos, so he made his own 3-servo shield. In the end, the prototype told him he had to redo some calculations, allowing him to move on to the final machine.

One thing we can say about the final machine is that hot glue must truly be the maker’s connect-all — you won’t find many screws here. Even the servos are held in place with copious quantities of glue. And the mechanism for lifting the pen is also quite clever. The whole thing is mounted on two vertical guide rods, so that it can easily slide up and down. To get it to actually move up and down, he glued a toy car wheel off-center on a servo arm. When the servo turns, the off-center wheel acts like a cam, pushing down on the wooden base to either lift the machine up or lower it down, depending on where the wheel is in its rotation.

See his hackaday.io page for the full step-by-step development process. But first check out the videos below to see how impressive such a simply made machine is in action.

Not all drawing machines have to be stationary though. Check out this drawing robot that rolls around the canvas in order draw. And if you want realistic portraits done, have a look at this delta robot aptly called Pythagoras.

Always wanted to be a citizen of Fire Nation? Here’s one way to ace the citizenship exam: punch-activated flaming kung fu gauntlets of doom.

As with all the many, many, many flamethrower projects we’ve featured before, we’ve got to say this is just as bad an idea as they are and that you should not build any of them. That said, [Sufficiently Advanced]’s wrist-mounted, dual-wielding flamethrowers are pretty cool. Fueled by butane and containing enough of the right parts for even a minimally talented prosecutor to make federal bomb-making charges stick, the gauntlets each have an Arduino and accelerometer to analyze your punches. Wimpy punch, no flame — only awesome kung fu moves are rewarded with a puff of butane ignited by an arc lighter. The video below shows a few close calls that should scare off the hairy-knuckled among us; adding a simple metal heat shield might help mitigate potential singeing.

Firebending gloves not enough to satisfy your inner pyromaniac? We understand completely.

Thanks to [Nils Hitze] for the hot tip. Yep.

Feel like breaking out of your streaming-induced vegetative state but can’t seem to break the binge-watching cycle? Maybe you’re a candidate for this exercise bike that controls how much Netflix you watch.

The concept behind [Roboro]’s anti-couch potato build is simple — just keep pedaling and you get to keep watching. The details are pretty simple too and start with an Arduino monitoring the signal coming from a jack thoughtfully provided by the manufacturer of his exercise bike. The frequency of the square wave is translated into a speed which a Python script on a PC reads over USB. Once a Netflix stream is started, dropping below the user-defined speed pauses the movie. The video below shows it doing its thing.

Improvements readily spring to mind, like adding a speed buffer so that pedaling faster lets you bank some streaming time and earn a rest. Maybe it could somehow integrate with these Netflix-enabled socks, or even with the Netflix and Chill button. But those sort of defeat the purpose a bit.

While it’s true that your parts bin might have a few parts harvested from outdated devices of recent vintage, there’s not much to glean anymore aside from wall warts. But the 3×48-character LCD from [Kerry Wong]’s old Uniden cordless landline phone was tempting enough for him to attempt a teardown and reverse engineering, and the results were instructive.

No data sheet? No problem. [Kerry] couldn’t find anything out about the nicely backlit display, so onto the logic analyzer it went. With only eight leads from the main board to the display module, it wasn’t likely to be a parallel protocol, and the video below shows that to be the case. A little fiddling with the parameters showed the protocol was Serial Peripheral Interface, but as with other standards that aren’t exactly standardized, [Kerry] was left with enough ambiguity to make the analysis interesting. Despite a mysterious header of 39 characters, he was able in the end to drive the LCD with an Arduino, and given that these phones were usually sold as a bundle with a base and several handsets, he ought to have a nice collection of displays for the parts bin.

With how prevalent this protocol has gotten, [Kerry]’s post makes us want to get up to speed on the basics of SPI. And to buy a logic analyzer too.

Everybody needs somebody sometimes, even if it’s just for when your back itches. But directing your itchy interlocutor to the correct spot can be a spatial relations challenge: “Right in the middle… no, down a bit… left… no, the other left! Harder! Wait, not that hard!” Why bother with all that messy interpersonal communication and human contact when you can build an automated, precision-guided back scratcher?

[VijeMiller] has aluminum extrusion tastes on a cardboard budget, but don’t let that put you off this clever build. The idea is pretty simple: a two-axis plotter that moves a rotary-action business end to any point within a V-shaped work envelope. The Arduino in the base talks to a smartphone app that lets you point to exactly the spot in need of attention on what for most of us would be an incredibly optimistic photorealistic map of the dorsal aspect of the body (mildly NSFW photo in the link above dips below the posterior border). Point, click, sweet relief.

The video below shows the rig in action, along with the Thespian skills we’ve come to know and love from [VijeMiller] with such classics as the fake floating 19th green, the no-idling-while-texting alert, and the more recent ker-sploosh fighting foam filled toilet. It does seem like he changed his name from [TVMiller] somewhere along the line, but he can’t throw us off the trail that easily.

Calling [Matt Barr]’s remote controlled hot air balloon a miniature is a bit misleading. Sure, it’s small compared with the balloons that ply cold morning skies with paying passengers and a bottle of champagne for the landing. Having been in on a few of those landings, we can attest to the size of the real thing. They’re impressively big when you’re up close to them.

While [Matt]’s balloon is certainly smaller, it’s not something you’d just whip together in an afternoon. Most of [Matt]’s build log concentrates mainly on the gondola and its goodies — the twin one-pound camp stove-style propane tanks, their associated plumbing, and the burner, a re-tasked propane weed torch from Harbor Freight. Remote control is minimal; just as in a full-size balloon, all the pilot can really do is turn the burner on or off. [Matt]’s approach is a high-torque RC servo to control the burner valve, which is driven by an Arduino talking to the ground over a 2.4-GHz RF link. The balloon is big enough to lift 30 pounds and appears to be at least 12 feet tall; we’d think such a craft would run afoul of some civil aviation rules, so perhaps it’s best that the test flight below was a tethered one.

Sadly, no instructions are included for making the envelope, which would be a great excuse for anyone to learn a little about sewing. And knowing how to roll your own hot air balloon might come in handy someday.

For those who love to hike, no excuse is needed to hit the woods. Other folks, though, need a little coaxing to get into the great outdoors, which is where geocaching comes in: hide something in the woods, post clues to its location online, and they will come. The puzzle is the attraction, and doubly so for this geocache with an Arduino-powered game of Hangman that needs to be solved before the cache is unlocked.

The actual contents of a geocache are rarely the point — after all, it’s the journey, not the destination. But [cliptwings]’ destination is likely to be a real crowd pleaser. Like many geocaches, this one is built into a waterproof plastic ammo can. Inside the can is another door that can only be unlocked by correctly solving a classic game of Hangman. The game itself may look familiar to long-time Hackaday readers, since we featured it back in 2009. Correctly solving the puzzle opens the inner chamber to reveal the geocaching goodness within.

Cleverly, [cliptwings] mounted the volt battery for the Arduino on top of the inner door so that cachers can replace a dead battery and play the game; strangely, the cache entry on Geocaching.com (registration required) does not instruct players to bring a battery along.

It looks like the cache has already been found and solved once since being placed a few days ago in a park north of Tucson, Arizona. Other gadget caches we’ve featured include GPS-enabled reverse caches, and a puzzle cache that requires IR-vision to unlock.

Thanks to [Dan Wagoner], who built the game upon which this is based, for the tip.

We love to see projects undertaken for the pure joy of building something new, but to be honest those builds are a dime a dozen around here. So when we see a great build that also aims to enhance productivity and push an entrepreneurial effort along, like this automated small parts counter, we sit up and take notice.

The necessity that birthed this invention is [Ryan Bates’] business of building DIY arcade game kits. The mini consoles seen in the video below are pretty slick, but kitting the nuts, bolts, spacers, and other bits together to ship out orders was an exercise in tedium. Sure, parts counting scales are a thing, but that’s hardly a walk-away solution. So with the help of some laser-cut gears and a couple of steppers, [Ryan] built a pretty capable little parts counter.

The interchangeable feed gears have holes sized to move specific parts up from a hopper to a chute. A photointerrupter counts the parts as they fall into plastic cups on an 8-position carousel, ready for bagging. [Ryan] also has a manual counter for wire crimp connectors that’s just begging to be automated, and we can see plenty of ways to leverage both solutions as he builds out his kitting system.

While we’ve seen more than a few candy sorting machines lately, it’s great to see someone building hardware to streamline the move from hobby to business like this. We’re looking forward to seeing where [Ryan] takes this from here.