Here’s an inexpensive electronic circuit that you can build to put in your Jack-o’lantern. It provides power to drive a few LEDs at night, and automatically turns them off during the daytime. It’s a simple and automatic dark-detecting circuit that you can use to for your very own photosensitive pumpkin.
Happy birthday to us! Evil Mad Scientist Laboratories is now two years of age. Collected below is a “Best of Evil Mad Scientist” for the past year: Some of our favorite projects that we’ve published over the last twelve months. Here’s to the next year!
Rubberbands made from old bicycle innertubes.
Light tent made from a lampshade.
Spool spinner from an old fan.
The $1.00 C to D adapter
How to make a Joule Thief from Make: Weekend Projects.
How to make a dark-detecting LED night light.
AVR microcontroller projects
Using an ADXL330 accelerometer with an AVR microcontroller
Printing complex shapes: Sugar Chain
Candyfab improvements: higher resolution and edible output
Observations & silly projects:
Forbidden Lego review & build
The Snap-O-Lantern is a robotic mini-pumpkin. Normally, it just sits there, in disguise as a boring old pumpkin. But, every twenty seconds he comes to life. His LED eyes turn on, his jaw slowly opens, and then SNAPS shut– and he goes back into stealth mode.
What’s inside? A small hobby servo motor, driven by an AVR microcontroller. This is a minimal microcontroller project, and is very straightforward if you happen to already have a setup for programming one. We’ll walk through the carving, setup, programming, and electronics. This is an open-source project, one of the world’s first “gpl-o-lanterns”; source code is provided.
A quick, low-tech halloween project: we hollowed out a couple of miniature decorative gourds. You can get these by the bagful at the grocery store, next to the mini-pumpkins. The one on the left had a kind of wrinkly base that adapted itself well to this shape, and the one on the right had more of a conical tip that we cut off to make a flat base.
Gourds like these have a hard shell, about 3 mm thick, that is rather hard to cut through. We used a loose drill bit (turned by hand) to make the initial cut. From there, a regular hobby knife (e.g., x-acto) works well. Once the soft flesh and seeds are scooped out, the hard shell can dry to make a semi-permanent display.
It’s unreasonably fun to walk around with one of these in each hand, reenacting the age-old chase drama. Especially when the little yellow dude chomps a big white dot. Now who’s chasing who?!?!
You can find more pumpkin projects in our Halloween Project Archive.
The MiniPOVs were created by AdaFruit Industries. They Rebelled. They Evolved.
And now, they may be invading your front porch.
It’s an open secret that here at evilmadscientist we go both ways: analog and digital.
So, here is yet another way to get a Cylon pumpkin circuit– a useful component for halloween. (Yes, you can do KITT too, we won’t stop you.) We’ll spare you the carved pumpkins and dive right into the details.
There seem to be a lot of MiniPOV kits out there. If you’ve got one, this is a fast way to make a passable slowly-scanning eye.
Note that we are not using the “POV” part of the MiniPOV– you don’t need to wave your pumpkin back and forth; it really is just a slowly-moving image.
This is a one minute project for some of you (you know who you are), but if you are really starting from scratch there isn’t any giant time advantage to going doing it this way instead of analog.
Once you have a working minipov, the first step is to download the firmware (4 kB .ZIP file) and unzip it. If you are programming the MiniPOV3 directly through its serial port,
pop open a terminal and move to the directory. Type (with a return after each line):
And… that’s it.
(If you have a GUI for programming AVRs and know how to use it, you can of course use that instead of programming through the terminal.)
If you are using some other AVR programmer or are programming a bare ATtiny2313 without a MiniPOV at all, you will need to edit the header of the included makefile to reflect the type of AVR programmer and the port where it is located. (And then, proceed with the instructions above.)
While this makes a pretty good looking pumpkin, there is still room for improvement in the firmware– the motion is reasonably smooth but doesn’t yet capture the incandescent fade that the analog versions do. I’ll leave it to the community to improve this firmware; if you have some better code, let me know and I’ll help roll it in.
Tim Charron sent in a greatly improved version of this program– please give it a try.
You can find more pumpkin related projects in our Halloween Project Archive.
This week the lab staff is heading off to Austin, Texas, our former stomping grounds and site of the other Maker Faire this year!
As we noted earlier, we’ll be doing a demonstration of how to build an excellent Bat Costume out of an umbrella and a hoodie. However, our primary project there will be our booth: High-Tech Pumpkins, where we will show up to a dozen (fingers crossed) halloween-themed projects, TSA willing. (Thank FSM it’s Austin, not Boston.)
While we get everything together this week, our publishing schedule will be a little wonky. However, halloween is just around the corner, so it’s time to dust off a few projects from our halloween archives!
How to hack LEDs into Lego minifigures for Halloween (Link)
Make a Flying Spaghetti Monster Costume (Link)
Crocodile Costume (Link)
Easy Itty-Bitty Blinky LED Jack-O’-Lantern (Link)
A Robotic Dalek Pumpkin (Link)
The fall holidays are fantastic ones: Halloween is all about costumes and candy and Thanksgiving is all about food. Here is how to make one of our favorite fall treats: pumpkin spice truffles. (Yum.)
To get the note-perfect flavor of traditional American pumpkin pie, we use the spice ratio from the old-standard can of Libby’s pumpkin (here is the recipe from under the label). Bittersweet chocolate has a stronger flavor than that of pumpkin, so we actually use twice the spice of a pie for a small batch (well, small for us batch) of truffles. The amazing thing is that these pumpkin-free wonders taste uncannily like pumpkin pie. Not that anyone will have trouble distinguishing your truffles and a pie, but you just might get asked, “Are these actually made with pumpkin?”
Continue reading Pumpkin Spice Truffles
Yay! We finally got our copy of the Make: Halloween Edition.
This special issue is actually available in two different covers, but we particularly like thisversion because of that little starburst: “Make an LED Jack-O’-Lantern!”
On page 60, you can find the article that we wrote about how to build the Larson Scanner (named after Glen A. Larson); a scanning eye for your old-school Cylon or KITT pumpkin projects.
The article is actually a slightly updated version of our project from last Halloween, Make A Cylon Jack-O-Lantern. Last year’s how-to is still online— and we have recently checked to make sure that all the parts on the parts list are still available.
Either way, let’s see those Cylons! If you build one, please post your pictures in the Evil Mad Science Auxiliary.
- Just in case you missed them, here they are:
- How to Build a Better Bat Costume
- Crocodile Costume
- How to hack LEDs into Lego minifigures for Halloween
- Make a Flying Spaghetti Monster Costume
- Make A Cylon Jack-O-Lantern
- Building a Robotic Dalek Pumpkin
- Easy Itty-Bitty Blinky LED Jack-O’-Lantern
Apparently the world was ready for the invasion of Cylon Jack-o-lanterns— They made it onto TV, into magazines, and presumably onto a lot of front porches as well. Lots of people made their own and we’ve rounded up a list of some of the Cylon pumpkins (and umbrella-bat costumes) that we spotted this year. Read on to see where they showed up!
Continue reading Halloween project round-up
Halloween is tomorrow! Do you want to bring a carved pumpkin to work, but aren’t allowed to burn candles in your cubicle? Do you want to carve a mini-pumpkin that’s simply too small for a candle?
Or are you just running late and need to make a procrastinator’s pumpkin?
If you said yes to any of these questions, we just might have the solution that you’re looking for. Here’s an easy way to make a tiny blinking-LED jack-o’-lantern.
The blinking LED circuit is borrowed from a Tirefly, a commonly available type of motion-sensitive light that attaches to the valve stem on the wheel of a bike or car. Our quick modification (less than five minutes and no soldering) defeats the motion sensor so that the LED can blink all day (or all night) for you. (For hardened geeks who want to solder something anyway, we’ll also show you how to mod the circuit to use a higher-capacity battery.)
[Update: (10/2008) A reader wrote in that they have had trouble getting the circuit to blink continuously; the tirefly circuit may have been changed. (Confirmed– It has changed!) Do any other readers have recent success or failure to report?]
Continue reading Easy Itty-Bitty Blinky LED Jack-O’-Lantern