Flickering Jack O’ Lantern Is An Easy Beginner Build

October 19, 2021 by Lewin Day 8 Comments

The Jack o’ Lantern is a fun Halloween tradition, though one that does come with a few risks. It’s pretty easy to slice off a bit of finger when carving a stiff pumpkin, and candles draw more enmity from fire crews than most household items. For the electronics beginner looking for a learning project, [Oyvind’s] build might be a nice safe bet.

The build starts with a 3D-printed pumpkin figurine with a suitably spooky face, though [Oyvind] notes there’s nothing stopping this project from being executed with a real orange gourd instead. Inside, an Arduino is hooked up to a trio of orange LEDs. They’re attached to PWM pins and each is given a random brightness value at regular intervals to create a pleasant flickering effect.

It’s a very simple project, but it’s also the kind of thing that’s perfect for introducing new people into the world of electronics. There’s little to get wrong, and mistakes aren’t costly, making it an ideal project for beginners. From there, the sky really is the limit! Video after the break.

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Ultrasonic Array Powers This Halloween Spirit Writer

October 12, 2021 by Dan Maloney 16 Comments

The spooky season is upon us, and with it the race to come up with the geekiest way to scare the kids. Motion-activated jump-scare setups are always a crowd-pleaser, but kind of a cheap thrill in our opinion. So if you’re looking for something different for your Halloween scare-floor, you might consider “spirit writing” with ultrasound.

The idea that [Dan Beaven] has here is a variation on the ultrasonic levitation projects we’ve seen so many of over the last couple of years. While watching bits of styrofoam suspended in midair by the standing waves generated by carefully phased arrays of ultrasonic transducers is cool, [Dan] looks set to take the concept to the next level. Very much still a prototype, the setup has a 256-transducer matrix suspended above a dark surface. Baking powder is sprinkled over the writing surface to stand in for dust, which is easily disturbed by the sound waves reflecting off the hard surface. The array can be controlled to make it look like an unseen hand is tracing out a design in the dust, and the effect is pretty convincing. We’d have chosen “REDRUM” rather than a pentagram, but different strokes.

[Dan] obviously has a long way to go before this is ready for the big night, but the proof-of-concept is sound. While we wait for the finished product, we’ll just file this away as a technique that might have other applications. SMD components are pretty small and light, after all — perhaps an ultrasonic pick-and-place? In which case, sonic tweezers might be just the thing.

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Get Yer Halloween On!

October 2, 2021 by Elliot Williams 3 Comments

Halloween is basically built for the hacker. Besides the obvious fabrication of absurd costumes, there’s also the chance to showcase your skills, be they mechanical, audio, or video. It’s also a great time to show off our coolest tricks to inspire the young proto-hackers. If you need inspiration, we’ve got 150 ideas.

My personal problem with Halloween, though, is that I always start at the last minute, and my ideas far outreach my time budget. Or because it’s all done in the last minute, a whole bunch of ideas that should “just work” in theory run into the immovable object that is practice. At least that’s what happened with last year’s spooky sound effects — my son and I spent so much time collecting and recording scary audio samples that I ran out of time while still getting the sensitivity on the motion detector set just right, and then the battery died halfway through the night.

But this year will be different, I swear! I’m going to get it done early and test it out, with the luxury of time to debug the inevitable spiders. And you can swear too. Get started now on your Halloween project. Or at least next weekend.

What’s your favorite Halloween Hack?

Contests

If you need any more encouragement to fire up your black and orange hacking machine, think of Hackaday.io’s Halloween Hackfest. It runs until Oct 28, and all you have to do to enter is document your Halloween project on IO and press the “Submit” button. The deadline is the 28th, which still gives you a couple of nights to debug whatever didn’t work before the real deal. Prizes are shopping sprees at Digi-Key, and Adafruit is doubling the gift certificate if you use any Adafruit parts in the build.

If you don’t give a pumpkin about stupid ol’ Halloween, that’s cool too. (Grinch!) The 2021 Hackaday Prize has entered the final wildcard round. If your project didn’t fit in any of the previous categories, I’m pretty sure it’ll fit just fine in the anything-goes phase. Go nuts. We’d love to see what you’re working on.

Left: kids stomping spiders projected on a driveway. Right: the setup.

Make This Halloween A Spider-Stomping Good Time

September 30, 2021 by Kristina Panos 11 Comments

We can count on one hand the number of times that we haven’t needed a coat on Halloween night around here. Even if it was fair and sunny the day before, you can count on Halloween being appropriately windy, cold, and spooky. Trick-or-treating only keeps a kid so warm, and we would have loved to happen upon a house with a spider-stomping sugar-burning good time of a game going on in the driveway.

[Kyle Maas] built this game a few years ago, and it has proved quite popular ever since. It’s so popular, in fact, that they have to have someone on duty with a vaudeville hook to yank spectators off the playing field. The point is to stomp as many spiders as you can in a set amount of time, though you only need to stomp one to win. It can handle one to four players, depending on the size of the projection, but [Kyle] says it’s kind of hard to track more than two at a time.

The setup is fairly simple, provided you can reliably affix your projector to something sturdy. [Kyle] used a Structure sensor for the 3D scanner, but you could easily use a Kinect instead. Conversely, the calibration was challenging. [Kyle] ended up using a DSP math trick known as the inverse bilinear transform to be able to calibrate the system using the 3D scanner itself.

If you’re more into scaring the children, just rig up a coffin bell. Either way, don’t forget about our Halloween Hackfest contest, running now through Monday, October 11th. There are more details over on IO. While you’re there, why not check out the list of entries?

Spooky Coffin Bell Spooks Passers By On Halloween

September 21, 2021 by Lewin Day 3 Comments

Being buried alive isn’t fun, we imagine. Fear of it led to the development of various safety coffin ideas in the 18th and 19th centuries, and [Glen Akins] wonderful Halloween prop riffs on that tradition today.

The safety coffin was a simple solution for those afraid that this might happen to them. One concept had a bell which was installed above freshly dug graves with a string extending into the coffin. One who found themselves accidentally buried alive could then pull the string to ring the bell and summon help.

[Glen’s] installation eliminates the coffin and the dead body, and simply mounts a bell on a post. Inside, there’s an ultrasonic rangefinder that detects passers by. When someone walks closely enough to the prop, a microcontroller triggers a servo which rings the bell with a haunting urgency.

It’s a simple build, but appropriately installed with its LED lighting, it really does pop. It would be a wonderful way to add atmosphere and mood to a Hallowe’en party or haunted house. We’ve seen some great Hallowe’en hacks over the years, and some of the best are pumpkins. Video after the break.

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New Contest: Halloween Hackfest

August 10, 2021 by Mike Szczys 4 Comments

It’s as if Halloween was made for hardware hackers. The world is begging us to build something cleaver as we decorate our houses and ourselves for the big day. And one thing’s for sure: the Hackaday crowd never disappoints. This year we’re fully embracing that with the Halloween Hackfest, our newest contest beginning today along with the help of our sponsors Digi-Key and Adafruit.

The animated video combined with the 3D-printed prop makes for an excellent effect.

Wait, isn’t it the beginning of August? Why are we talking about Halloween? The procrastinator’s dillema, that’s why! Start working on your build now and it will be epic by the time the day actually rolls around. Decorating for trick-or-treaters is a good place to start. For our money, projected heads are a really cool party trick, like these singing Jack-o-laterns, or these disembodied heads inspired by Disney’s Haunted Mansion. Or maybe you’re more of a flamethrower-hidden-in-pumpkin type of person?

It doesn’t take much tech to bring a good costume to life — a few LED strips make a plain old princess dress light up the night and builds some permanent memories for the lucky little one who’s wearing it. Speaking of memories, we doubt the little one will remember this mechwarrior family costume, which is why you’ve always got to make a video of these things.

Over the year’s we’ve seen claw machines for candy delivery, and even a pumpkin piano. Of course pumpkin carving is an entire category unto itself where five-axis CNC machines are fair game. Look around, get inspired, and build something!

Three top winners will receive $150 shopping sprees in Digi-Key’s parts warehouse. If your build happens to use an Adafruit board, your prize will be doubled. We’ll also be awarding some $50 Tindie gift cards to the most artistic projects.

Get started now by creating a project page on Hackaday.io. In the left sidebar of your project page, use the “Submit Project To” button to enter in the Halloween Hackfest. You have from now until October 11th to spill the ~~beans~~ pumpkin seeds on what you’ve made.

Teach Your Air Compressor To Blow Eggs

June 7, 2021 by Kristina Panos 16 Comments

As fun as it is to decorate Easter eggs, the road to a hollow hen’s egg is a gross and gooey avenue. Trust us, it sucks to blow out eggs, and it’s hard to get it right. Plus, you know, there’s that whole salmonella thing. [Phil] decided to speed things up this year by using an air compressor to do the dirty work.

Of course, one must approach this problem delicately because eggs are fragile. It would be nice to drill the egg instead of poking the end with a needle, but how are you gonna pull that off without breaking it? As it turns out, all you need is a bench vise, the right piece of PVC, a bit of rubber to keep the egg safe, and some hose clamps to keep the business part together.

[Phil] built a two-stage contraption that serves both purposes — the bottom cup safely cradles the egg for drilling, and the identical top cup connects to the air compressor, which blows the goo out of the bottom hole. [Phil] might have used negative pressure instead, but doesn’t have a vacuum pump or hose. Be sure to check out the brief demo video below.

Don’t want to mess around with real eggs? There are tons of ways to beautify fake eggs, but few of them are as cool as lasers.

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