2023 Halloween Hackfest: Organ-playing Skeleton Livens Up Halloween

Every hacker appreciates how off-the-shelf parts can be combined into something greater, and [bryan.lowder] demonstrates this beautifully with his organ-playing skeleton, a wonderful entry to our 2023 Halloween Contest!

Skelly the 3-foot-tall novelty skeleton animatedly plays Bach’s Toccata and Fugue in D Minor while perched at an old (and non-functional) Hammond organ. The small animatronic skeleton has canned motions that work very well for mock organ playing while an embedded MP3 player takes care of playing the music.

That’s not to say the project didn’t have its challenges. Integrating off-the-shelf components into a project always seems to bring its own little inconveniences. In this case, the skeleton the MP3 player both expect to be triggered with button pushes, but taping the button down wasn’t enough to get the skeleton moving when power was applied. [bryan] ended up using relays to simulate button pushes, and a 555 timer circuit to take care of incorporating a suitable delay.

As [bryan] puts it, “a technical tour de force it ain’t, but it is practical and it works and it was done on time” which is well said. Watch Skelly in action in the video, embedded below. There’s also a second video showing the homebrewed controller and MP3 player, both concealed under Skelly’s robe.

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Dead E. Ruxpin Appears Alive And Well

What are you doing to scare trick-or-treaters this Halloween? Surely something, right? Well, Hackaday alum [CameronCoward] certainly has his holiday under control with Dead E. Ruxpin, a murderous, cassette tape-controlled animatronic bear.

Readers of a certain vintage will no doubt see the correlation to Teddy Ruxpin, an animatronic bear from the 1980s whose mouth moved as it read stories from cassette tapes. Cleverly, the engineers used one stereo channel for the story’s audio, and the other channel to control the bear’s mouth.

Dead E. Ruxpin takes this idea and expands it, using the same two channels to send audio and control three servo motors that move both arms and the mouth. How is this possible? By sending tones built from one or more frequencies.

Essentially, [Cameron] assigned a frequency to each movement: mouth open/closed, and left and/or right arm up or down. These are all, of course, synced up with specific points in the audio so Dead E. doesn’t just move randomly, he dances along with the music.

The bear is actually a hand puppet, which leaves room for a 3D-printed skeleton that holds the RP2040 and the servos and of course, moves the puppet’s parts. We can’t decide if we prefer the bulging bloodshot eyes, or think the cutesy original eyes would have made a scarier bear. Anyway, check out the build/demo video after the break to see it in action.

Are you now into Teddy Ruxpin? Here’s a bit more about those scare bears. And don’t forget, Halloween Hackfest runs now until October 31st.

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Realistic Animatronic Eyes Are An Easy DIY Build

It’s not Halloween yet, but if you’re planning a technically-complicated costume, it might serve you well to start building now. To that end, here’s a guide from [Ikkalebob] on how to produce a compact animatronic eye mechanism.

The eye is inspired by mechanisms used in professional animatronics. However, that doesn’t mean it’s hard to build. Complex machining is done away with in favor of readily reproducible 3D-printed components. The eyes are able to look in different directions and can move realistically, and the build includes working eyelids that have a great blinking action to them that feels very natural. An Arduino Uno is charged with running the eyes, paired with a bunch of hobby servos and an Adafruit PCA9685 servo driver. A hefty 5V, 4 amp power supply is on hand to deliver enough juice so the servos move smoothly without stuttering.

It’s the kind of thing that’s perfect for your spooky familiar, or installing eyes in the back of your head. It would be perfect to hide behind a window or in the bushes, too. Video after the break.

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Teardown: How Many Teddy Ruxpins Does It Take To Start A Coven?

Well, I did it. I conquered my childhood fear of talking bears and brought a vintage Teddy Ruxpin animatronic stuffed bear into my home. There were and still are plenty of his brethren both young and old to choose from on the auction sites, and when I saw this particularly carefree barefoot Teddy in his Hawaiian shirt and no pants, I was almost totally disarmed. Plus, the description promised a semi-working unit with a distorted voice, and who among us could resist a specimen in such condition? Maybe the tape deck motor is going out, or it just needs a new belt. Maybe the tape itself messed up, and Teddy is fine. I had to find out.

But let me back up a bit. If you don’t know what I’m talking about, Teddy Ruxpin was a revolutionary toy that dropped in 1985. It’s a talking teddy bear that reads stories aloud, all the while moving his eyes and mouth to the sounds. Along with Teddy came special cassette tapes, corresponding story books, and outfits. I wanted one when I was a kid, but was also kind of scared of them. Since they were so expensive — about $250 inflation-adjusted for the bear and a single tape / book / outfit, plus another $15 for four D cells — I never did get one in my youth.

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Enjoy This Animatronic Eyeball’s Smooth Moves

[Enza3D] shows off a surprisingly compact articulated animatronic eyeball that can be intuitively controlled with a Wii nunchuk controller. The design uses 3D printed parts and some tiny servos, and all of the necessary electronics can be easily purchased online. The mechanical design of the eye is very impressive, and [Enza3D] walks through several different versions of the design, the end result of which is a tidy little assembly that would fit nicely into masks, costumes, or other projects.

A Wii nunchuk is ideal for manual control of such a device, thanks to its ergonomic design and ease of interface¬†(the nunchuk communicates over I2C, which is easily within the reach of even most modest of microcontrollers.) Of course, since driving servos is also almost trivial nowadays, it doesn’t look like working this into an automated project would pose much of a challenge.

The eyeball looks great, but if you want to try for yourself, accessing the design files and code will set you back $10 which might look attractive if an eye like this is the missing link for a project.

On the other hand, enjoying the video (embedded below) and getting ideas from [Enza3D]’s design notes will only cost you a few minutes.

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Peek Behind The Curtain Of This Robotic Mouse

At first glance, this little animatronic mouse might seem like a fairly simple affair. A door opens, our rodent friend pops its head out, looks around, and goes back in. But just like in The Wizard of Oz, a strategically placed curtain is hiding the impressive array of gadgetry that makes the trick possible.

Creator [Will Donaldson] has put together a fantastic write-up of just what went into creating this little fellow, and we think you’ll be surprised at just how serious the mechanics involved are. Take for example the rig that provides horizontal motion with a NEMA 17 stepper motor mated to a 200 mm leadscrew and dual 8 mm rail assembly that would like right at home as part of a 3D printer.

The star of the show rides atop a beefy sliding carriage assembly made of printed components and acrylic, which is linked to the door via a GT2 timing belt and pulley in such a way that it automatically opens and closes at the appropriate time. To inject some life into the puppet, [Will] stuffed it with a pair of SG90 servos in a sort of pan-and-tilt arrangement: the rear servo turns the mouse’s body left and right, while the forward one moves the head up and down.

An Arduino Uno controls the servos, as well as the stepper motor by way of a TB6600 controller, and optical limit switches are used to make sure nothing moves out bounds. [Will] is keeping the CAD files and source code to himself for the time being, though we imagine a sufficiently dedicated mouseketeer could recreate the installation based on the available information.

This would¬†appear to be the first animatronic mouse to grace the pages of Hackaday, but we’re certainly no strangers to seeing folks imbue inanimate objects with lifelike motion.

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ESP32-Cam Makes A Dandy Motion Detector

Halloween is right around the corner and just about every Halloween project needs some kind of motion sensor. Historically, we’ve used IR and ultrasonic sensors but [Makers Mashup] decided to use an ESP32-Cam as a motion sensor in his latest animatronic creation. You can see a video of the device and how it works below.

The project is a skull that follows you around with a few degrees of motion on a stepper motor. There’s a 3D-printed enclosure to make the hardware assembly easy. The base software was borrowed from [Eloquent Arduino].

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