2023 Halloween Hackfest: Meet Creepsy, The Robotic People-Seeking Ghost

November 4, 2023 by No comments

The 2023 Halloween Contest might be over, but we saw some great entries and clever modifications bringing projects into the Halloween spirit. One of them is Creepsy by [Hazal Mestci], a Raspberry Pi-based robotic ghost able to autonomously pick people out of a crowd and glide towards them, emitting eerie sounds as it does so.

The tech behind Creepsy (GitHub repository) originally led the somewhat less spooky existence of a mobile drink serving platform. But with a little bit of modification and the addition of a bedsheet with cutouts for sensors, the transformation into an obstacle-avoiding people-seeking spooker was complete. Key to this transformation was the Viam Python SDK, a software Swiss army knife used by robot builders everywhere. Creepsy itself was built using handy aluminum extrusion, and 3D printed parts along with the requisite suite of motors, cameras, and ultrasonic sensors.

Thanks to everyone who participated in the 2023 Halloween Contest. Got an idea for next year? It’s never too early to get started because ideas are great, but nothing beats “done on time”!

2023 Halloween Hackfest

Machine Teaches Morse Code

November 3, 2023 by 4 Comments

If you are a ham radio operator of a certain age, you probably remember ads for “The Instructograph,” a mechanical device for learning Morse code. [Our Own Devices] has an ancient specimen of the machine and shows us how it works in the video below. The machine is a model of simplicity. You wind up a spring-driven motor like you would for an old record player or music box. A slider sets the playback rate, and paper tape starts to spin.

The paper tape looks like computer tape, but since it only has literal long and short notches, it has two distinct sides. When you learned one set of messages, you could flip the tape over and get more practice that way. How did the machine read the paper tape? With a mechanical contact. Literally, if the paper had a hole in it, you made the circuit. If it didn’t, the circuit was broken. A buzzer and batteries or some other kind of sounder was all you needed.

The company was in business for 50 years. The newer versions had more electronics, but they always used the paper tape mechanism to store the code practice sessions. A 1962 ad noted that the machine could play back the tapes from three words a minute up to 40. You could buy or rent the machine, and we always assumed it was pretty pricey for its day. Around 1965, a new unit would cost $53 but did not include a headset or a key. So that was actually more reasonable than we expected. In 1965, a brand-name clock radio cost about $50, so it wasn’t any more than that.

Everyone has their own favorite method for learning code, especially [Ludwig Koch]. At least you don’t have to learn Alex-style.

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Homebrew TEM Cell Lets You EMC Test Your Own Devices

November 2, 2023 by 14 Comments

Submitting a new device for electromagnetic compatibility (EMC) testing seems a little like showing up for the final exam after skipping all the lectures. You might get lucky and pass, but it really would have been smarter to take a few of the quizzes to see how things were going during the semester. Similarly, it would be nice to know you’re not making any boneheaded mistakes early in the design process, which is what this DIY TEM cell is all about.

We really like [Petteri Aimonen]’s explanation of what a TEM cell, or transverse electromagnetic cell, is: he describes it as “an expanded coaxial cable that is wide enough to put your device inside of.” It basically a cage made of conductive material that encloses a space for the device under test, along with a stripline going down its center. The outer cage is attached to the outer braid of a coaxial cable, while the stripline is connected to the center conductor. Any electric or magnetic field generated by the device inside the cage goes down the coax into your test instrument, typically a spectrum analyzer.

[Petteri]’s homebrew TEM is made from a common enough material: copper-clad FR4. You could use double-sided material, or even sheet copper if you’re rich, but PCB stock is easy to work with and gets the job done. His design is detailed in a second post, which goes through the process of designing the size and shapes of all the parts as well as CNC milling the sheets of material. [Petteri] tried to make the joints by milling part-way through the substrate and bending the sheet into shape, but sadly, the copper didn’t want to cooperate with his PCB origami. Luckily, copper foil tape and a little solder heal all wounds. He also incorporated a line impedance stabilization network (LISN) into the build to provide a consistent 50-ohm characteristic impedance.

How does it work? Pretty well, it seems; when connected to a TinySA spectrum analyzer, [Petteri] was able to find high-frequency conductive noise coming from the flyback section of a switch-mode power supply. All it took was a ferrite bead and cap to fix it early in the prototyping phase of the project. Sounds like a win to us.

2023 Halloween Hackfest: Spooky Noise Maker Is Self-Contained

November 1, 2023 by 4 Comments

We just love it when y’all build off of each other’s projects. This spooky Halloween noise maker from [C.M. Herron] is no exception. But while the projects we’ve seen lately rely on external computers and/or guitar pedals to create the effects part of the build, this one has everything running on a Raspberry Pi that sits inside the box.

Readers of a certain vintage will recognize this as an 8-track storage box, on top of which are several noise-making objects that creak and ting and reverberate nicely. A USB microphone picks up the sounds, and by using a regular microphone instead of a piezo, [C.M.] can introduce varying levels of feedback to make the sounds even spookier.

So, how did [C.M.] make this work on a Pi 4? To put it simply, they’ve got the Reaper DAW and Windows Valhalla plugins running on top of WINE, which running on top of Box64, which is running on top of the Bullseye Pi OS. [C.M.] sure learned a lot from this build, and hopes to inspire others to build their own spooky noise boxen. Plus, they’ve already thought of ways to improve it for next year. Be sure to check it out in action after the break.

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2023 Halloween Hackfest: Quoth The Raven, “Caww!”

October 31, 2023 by 5 Comments

Sometimes, projects start in somewhat unlikely places. This one began when [Istvan Raduly] scored a fake raven at a neighbor’s garage sale and decided to turn it into a thunder-and-lightning decoration that would frighten even the bravest trick-or-treater.

Get close enough to this raven and you’ll set off the PIR sensor, which triggers lighting and sound effects, including some spooky glowing and blinking red eyes, general cawing, and of course, thunder. The light comes from a whopping 10-watt, 12-volt power LED. This bird’s brain is an Arduino Nano, which is protected from the 12V supply with a boost converter. As you might expect, the sounds are on an SD card and played through a DF Player Mini.

Spookiness aside, our favorite part might be the absolutely lovely job that [Istvan] did decorating the raven’s base. Hiding electronics and hot glue is one thing, but this is above and beyond. Be sure to check it out after the break, both in the safety of the house, and outside in the scary darkness.

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Black 4.0 Is The New Ultrablack

October 31, 2023 by 100 Comments

Vantablack is a special coating material, moreso than a paint. It’s well-known as one of the blackest possible coatings around, capable of absorbing almost all visible light in its nanotube complex structure. However, it’s complicated to apply, delicate, and not readily available, especially to those in the art world.

It was these drawbacks that led Stuart Semple to create his own incredibly black paint. Over the years, he’s refined the formula and improved its performance, steadily building a greater product available to all. His latest effort is Black 4.0, and it’s promising to be the black paint to dominate all others.

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2023 Halloween Hackfest: Hack Skellington Is The Life Of The Party

October 29, 2023 by No comments

[Matt Vella] has had a talking, non-posable skeleton knocking around for years. As cool as that sounds, [Matt] is really tired of its three stock phrases. Fast forward to this year — [Matt] got a posable skeleton and decided to go all out on this, the hackiest of all holidays. The result? Hack Skellington.

Between the eye socket-mounted camera, the speaker, and servos in the head, jaw, and one arm, Hack Skellington is decked out to scare trick-or-treaters (or anyone who gets close enough) in modern fashion. Thanks to ChatGPT and an AI-generated voice, Hack can recognize people and welcome them by name, look people in the eye, or simply move its arm when someone gets too close.

The brains of this operation is a Radxa Zero SBC programmed in Viam, though any SBC with Wi-Fi, GPIO, I²C, and USB should work just fine. [Matt] only spent about $150 total, half of which went to the skeleton itself. Be sure to check the spooky action out after the break.

You have until 9 AM PT on Tuesday, October 31st to enter the 2023 Halloween Hackfest. Procrastinators unite! Don’t want to animate a whole skeleton? Come to think of it, a severed, animated hand is even creepier, anyway.

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