8×8 LED Arrays Make for one Creepy Animated Pumpkin

[Michal Janyst] wrote in to tell us about a little project he made for his nephew in preparation for Halloween - a jack-o-lantern with facial expressions.

Pumpkin Eyes uses two MAX7219 LED arrays, an Arduino nano, and a USB power supply. Yeah, it’s pretty simple — but after watching the video you’ll probably want to make one too. It’s just so cute! Or creepy. We can’t decide. He’s also thrown up the code on GitHub for those interested.

Of course, if you want a bit more of an advanced project you could make a Tetris jack-o-lantern, featuring a whopping 8×16 array of LEDs embedded directly into the pumpkin… or if you’re a Halloween purist and believe electronics have no place in a pumpkin, the least you could do is make your jack-o-lantern breath fire.

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Simple LED Project to Spice Up Your Halloween Party

[Paul's] project is a great example of how you can take a simple project and turn it into something more interesting. He built himself a jack-o-lantern with an Internet controlled RGB LED embedded inside.

[Paul] first wired up an RGB LED to a Raspberry Pi. He was sure to wire up each color using a 100ohm resistor to prevent the LED from burning out. The web interface was written in Python. The interface is pretty simple. It consists of three text fields. The user enters a value between 0 and 255 for each of the three LED colors. The program then lights up the LED accordingly.

[Paul] realized he would need a diffuser for the LED in order to really see the blended colors properly. Instead of using a common solution like a ping-pong ball, he opted to get festive and use a plastic jack-o-lantern. [Paul] removed the original incandescent bulb from the lantern and mounted the LED inside instead. The inside of the pumpkin is painted white, so it easily diffuses the light. The result is a jack-o-lantern that glows different colors as defined by his party guests. Be sure to check out the demonstration video below.

Hacklet 20 – Halloween Hacks

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Hey, did you know that Hackaday.io is continuously being updated and improved? One of the coolest features this week is the new LaTeX based equation editor. That’s right, you can now put symbols, equations, and all sorts of other LaTeX goodies into your posts. Check out [Brian Benchoff's] LaTeX demo project for more information.

Every holiday is a season for hacks, but Halloween has to be one of the best. From costumes to decorations, there are just tons of opportunities for great projects. We know that with an entire week left before the big day, most of you are still working on your projects. However a few early bird hackers already have Halloween themed projects up on Hackaday.io. We’re featuring them here – on the Hacklet!

pumpkin1[philmajestic] is in the Halloween spirit with his AVR Halloween Pumpkin. [Phil] created a motion activated Jack-o’-lantern with an ATmega328 as its brain. The AVR monitors a PIR motion sensor. When motion is detected, it flashes Jack’s LED eyes and plays spooky sound files from a WTV-020-16sd audio player. This is a great example of how a bit of work can create something cooler and infinitely more flexible than a store-bought decoration. Nice work [Phil]!

littlebitsPortraitThe littleBits crew have been working overtime on Halloween hacks this year. We definitely like their Halloween Creepy Portrait. A motion trigger, a servo, and a few glue bits are all it take to turn a regular portrait into a creepy one. When the motion detector is triggered, the servo moves a paper behind the portrait’s eyes. The replacement eyes look like some sort of demon or cat. Definitely enough to give us nightmares!

ironman[jeromekelty] helped his friend [Greg] build an incredible Animatronic Iron Man MKIII suit. The suit features RFID tags which trigger suit features. Since we’re talking about an Iron Man suit, “features” are things like shoulder rockets, boot thrusters, and a helmet that lifts up to reveal “Tony Stark”. No less than four Arduinos handle the various I/O’s. The suit even features an Adafruit WaveShield for authentic sounds! The electronics are just one piece of the puzzle here. [Greg] is a card-carrying member of the Replica Prop Forum. His MKIII suit is incredibly detailed. We especially like the weathering and battle damage!

tenticlesFinally, [Griff's] son is going to be wearing a Crochet Cthulhu Mask, with Arduino controlled tentacles for Halloween this year. [Griff] is an experienced crochet hobbiest. He’s mixing his love of needlework with his love of electronics to build the animated Cthulhu mask for his 4-year-old son. The mask is based on a free crochet pattern from ravelry, though [Griff] is making quite a few changes to support his application. The mask will be smaller to fit a 4-year-old, and will contain servos to move the tentacles. We haven’t heard from [Griff] in a while, so if you see him, tell him to post an update on the mask!

If you haven’t started working on your Halloween hacks, get busy! But don’t forget to upload them to Hackaday.io! If we get enough, we’ll run a second Hacklet with even more great projects. Until then, you can check out our Halloween Projects List!

That’s about it for this frightful episode The Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Add CNC to your…Propane Tank??!?

It’s starting to be that time of year again; the Halloween-themed hacks are rolling in.

[John Lauer] needed a propane-powered flame effect for his backyard ICBM “crash site”. Rather than pony up for an expensive, electronically-controlled propane
valve, he made a custom bracket to connect a stepper motor to the propane burner’s existing valve.

With the stepper motor connected up, a TinyG stepper motor controller and [John's] own graphical interface, ChiliPeppr, take care of the rest.

The hack is almost certainly a case of “everything looks like a nail when you have a hammer” but you have to admit that it works well and probably didn’t take [John] all that much time to whip up. Maybe everyone should have a couple spare stepper motors with driver circuitry just lying around ready to go? You know, just in case.

All the details of the build are in the video. If you’re done watching the flames, skip to around 2:50 where we see the adapter in action and then [John] steps us through its construction.

You may have seen coverage of the TinyG motor controller here before.

Additional thanks to [Alden Hart] for the tip.

Retrotechtacular: Lighting the Way for Talkie Pictures with Optical Sound Recording

This week’s Retrotechtacular is a 1943 Encyclopædia Britannica film focusing on optical sound reproduction for motion pictures. Both the sound and the images are recorded on film, which is only affected by light. Therefore, the sound waves must be converted to changes in light.

This is done the way you might expect: the sound waves hit a microphone and the changes in current are amplified and used to control the intensity of light falling on the film. Three types of soundtracks are described and wonderfully demonstrated at the end of the film.

All three types are made from a series of thin bars of light, and the corresponding current value is represented by changes in either their length or their width. In the Unilateral Variable Area recording, the bars extend from the right side of the sound track. Bilateral Variable Area recorded bars emanate uniformly toward the edges from the center. In Variable Density recording, all of the bars extend from the left to right extremes, but their thickness varies.

Variable Density recording is done with a light valve, which contains a pair of delicate metallic ribbons in a magnetic field that move like shutters when the sound current flows through them. The light coming through to the film is varied by the slot created in the space between the ribbons. The light patterns are changed back to sound through a photoelectric cell, which converts the variations in light back to changing current. These changes are amplified and run through a loudspeaker. Be sure to watch to the end to catch a demonstration of the recording methods, set to what we’re pretty sure is Camille Saint-Saëns’ Danse Macabre.

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Halloween Links: October 30th, 2013

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Happy Halloween from everyone at Hackaday! To help you enjoy the holiday here are a few festive links:

[Mike Kohn] whipped up a set of motion tracking eyeballs to make his decor extra creepy.

There’s not much to this jet-pack costume but the results are pretty amusing.

The eyes on [Tim Butler's] skeleton prop don’t follow you around the room, but they do use a PIR sensor to light up the skull.

Speaking of skulls, [Tom] is using some real skulls as decorations. He also added lights where the eyeballs should be, but he is using a photoresistor and comparator to turn on some LEDs.

[Clark] built a Mecha Robot Warrior costume for his son. With all of those LED strips we think he’ll be pretty safe when crossing the street!

And finally, [Jesse] added a lot to his prop in order to produce a Sinister Joker. That’s Joker-as-in-cards and not as in Batman. It’s got an IR distance sensor as a trigger, with a motor to move the wrist, lights for the eyes, and a sound shield to give it a disturbing voice.

Light Controller Goes Overboard for Halloween

floodbrain-halloween-light-controller

Yep, we said it. This Halloween decoration goes way overboard… and we love it! Not only does [Shelby Merrick] put on an incredible sound and light show for the neighborhood, but he keeps us happy by posting all the details for the lighting controller he designed. He calls the creation FloodBrain as it’s switching a set of flood lights to achieve the effects seen above. But for the full experience you’ll want to watch the demo videos below as well.

He needed a way to switch twelve RGB flood lights which pull 10 Watts. His controller was designed to communicate with them via RS485, with an AVR Xmega8E5 controlling the system. We like it that he included some images of the manufacturing process, using a stencil for solder paste before placing components for reflow.

The floodlights themselves are also an interesting hack. To get what he wanted at the best price he picked up 10W white LED flood lights for about eight bucks a piece, then swapped out the LED itself for an RGB version (same wattage) using the same heat sink and case.

More often that not we see this type of system controlling Christmas lights. [Shelby] mentions that he did get help from Christmas light controller forum We also think he should have no problem repurposing the controller for that type of application.

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