Halloween Hacks: Simple robotic skull is a perfect last minute decoration

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simple_talking_skull

If you haven’t taken the time to put your decorations together it’s time to get a move on. With Halloween just around the corner big elaborate displays are pretty much out of the question, but [Boris] and the team over at Open Electronics have a simple project that’s sure to be a hit with the Trick or Treaters.

Using a cheap plastic prop that you can likely find at any Halloween store, they have put together a simple talking skull that moves along with whatever music or sound is being piped through it. The skull’s mouth is moved by a single servo mounted inside the brain cavity, which is controlled by an Arduino. The Arduino monitors the sound level of the source audio being played, actuating the servo accordingly.

It’s quick, simple, and effective – perfect for a last minute decorating project. If you are a little more ambitious, you could always put together a whole chorus of skulls without too much additional effort – just a few extra skulls and some servos would do the trick nicely.

Check out a quick video of the skull in action below, along with another short clip showing how the servo is rigged up to move its mouth.

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Halloween Hacks: Terrifying mask follows you everywhere

It’s less than 5 days away from Halloween and the projects to scare small children are pouring in. [Noel] sent in his robotic Halloween mask he’s been working on, and the only way his build could be any better is by placing it underneath a child’s bed.

[Noel] took the mask he used last year and stuffed a few styrofoam craft balls inside to ‘fill it up.’ Two LEDs and a PIR sensor were fitted into the eyes of the mask and a few more electronics added to the brain. A servo was fitted to the base of the project to turn the head left and right.

The build uses a Gizduino Arduino clone with an Adafruit Wave shield. After a little bit of wiring up the LEDs, PIR sensor and neck servo, [Noel] had a bit of coding ahead of him. He ran into a problem with the WaveHC and Servo libraries because they both used the same timer. After finding a another software-based servo libraries, he had a reasonably terrifying project to put in front of a bowl of candy.

Check out the video below for a demo of [Noel]’s work.

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Halloween Hacks: Flickering Jack-o’-lantern

The dollar store is always a great place to find some weird stuff, so when [jethomson] found a flickering Jack-o’-lantern, he thought it would make a great project for the 74xx logic competition.

Instead of using the flickering incandescent lightbulb that came with the blinking pumpkin, [jethomson] decided to rebuild a blinking circuit around a 74HC14 Hex inverting Schmitt trigger IC. The chip was used as a relaxation oscillator by adding a resistor and cap from the input to the ground. After a bit of component selection and some calculation, he had a red and blue LED blinking at 2,6,9, and 15 Hz.

The result is a seemingly random pattern of light that looks like a ghostly blue after image of the handheld Jack-o’-lantern. While it may not be one of the most complex builds for the 74xx competition, it gets points in our book for originality.

Although [jethomson] says his camera doesn’t pick up his project very well, he did post a video of the Jack-o’-Lantern in action. Check it out after the break.

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Halloween Hacks: Diorama-rama

The folks down at LVL1, the Louisville hackerspace, are throwing a Halloween party. To showcase his building skills, LVL1 member [JAC_101] put together a Halloween diorama featuring the inner workings of Doctor Frankenstein’s laboratory.

There’s a bunch of really neat pieces that make this build great. First up is the LVL1 plasma sign. This sign is four circuits pumping a high voltage charge through Xenon flash tubes. Instead of a bright flash, a very Halloweeny Xenon plasma shoots though the tubes. The sign is constructed from four disposable camera flash circuits.

A few flickering-LED torches light Dr. Franenstein’s lair while the monster is a McDonalds happy meal toy wrapped in surgical tape and painted with UV reactive paint.

In the interests of repurposing existing materials, a plasma disc belt buckle was taken from [Seven of Nine]’s regeneration chamber LVL1’s rave supply cabinet and provides a suitable ‘mad scientist’ aesthetic. A bit of EL wire was thrown in for good measure along with some black lights to activate the UV paint.

While Frankenstein’s lab is missing a hilariously oversize knife switch on the wall, [JAC_101] still pulled off a great build.

Halloween Hacks: Scaring small children with Huffman coding

The team over at NerdKits decided they needed to do something for Halloween. Only on Halloween is scaring small children is an admirable goal, so they demoed a way to play creepy sounds after a door has been opened.

To trigger the sound, a magnetic reed switch from an alarm system is attached to a front door. This triggers the microcontroller and with a bit of delay, some creepy audio can be played on a pair of speakers. The team decided to store all the audio data on the flash memory of their ATmega328p, but that wouldn’t allow for a very long scream. To extend the length of the wails of the damned, the NerdKits team decided to use Huffman coded audio.

Because Huffman coding relies on the most common value being assigned the shortest code, the team used a bit of Python and C magic to figure out the optimal encoding for their audio file. After the evil laugh was sufficiently compressed, the microcontroller was programmed to decode the audio and send it to a pair of speakers. The team made all the software for their project available here for your perusal.

Although this project could be thrown together in an hour with an Arduino and an MP3 shield, the NerdKits team wants to get kids to learn how things work, also an admirable goal. [Humberto] from NerdKits put a video up explaining the theory of the project. Check it out after the break.

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Announcing our next theme: Halloween hacks

It seems every year, Hack A Day is a little bit behind the times when it comes to Halloween hacks. Builds like the Mario costumes and the house singing Thriller are great, but it makes a lot more sense for us to post them before Halloween.

To introduce our Halloween theme, we’d like to present [heavyweighthowe]’s Halloween project. It’s a small lighting automation build that syncs a string of lights to the theme of the best Halloween Christmas 2nd best [Tim Burton] movie, The Nightmare Before Christmas. [heavyweighthowe] used Vixen to sequence the lights and an Arduino to interpret the serial commands from Vixen. It’s a nice build that would look great sitting on a porch next to a giant bowl of candy.

If you’ve got a Halloween build you’d like to show off, like a haunted house ride an awesome costume or even a really great Jack-O-Lantern, send it in on the tip line. We’re planning on putting up at least one Halloween post a day, so keep sending in those builds.