Category Archives: Electronics

The Larson Scanner Kit

pumpkin
Today we’re releasing a new open-source project and kit, which is an updated approach to the “Larson Scanner.” The Larson scanner is named in honor of Glen A. Larson, the man responsible for producing both the original Battlestar Galactica and Knight Rider television shows, and consists of a set of red LEDs that scan back and forth.

Three years ago, we showed how to make a Cylon Jack-O-Lantern, in what has become one of our all-time most popular tutorials. The circuit for that project was based on a 555 timer, driving a 4017 decade counter, and has 6 pixels of resolution. To create the incandescent fading effect, we added low-pass transistor drivers. We also wrote up a version of that article for the 2007 Make Magazine Halloween special, which included a slightly nicer version of that same circuit.

And while it’s been popular, we’ve always had some nagging reservations about it, and in particular its battery life. This year, we decided to do something about it and made a much betterversion of the Larson Scanner, and so here it is:

bright
Continue reading The Larson Scanner Kit

Some thoughts on throwies

Throwies - 03

We’re big fans of LED throwies and derivative projects where you light an LED simply by connecting it across the terminal of a small lithium coin cell.

You’ll find this trick used in a lot of our projects that call for simply lighting up an LED in a tiny space, like the temporary LED lanterns, LED Ghosties, Robogames awards,
LED origami circuitry, light-up Lego minifigures, and edge-lit holiday cards. You’ll also find them in those little keychain flashlights– open one up and there’s just a battery and an LED.

So the throwie (and I use the term loosely, referring to devices with or without magnets) is a darned useful thing. But the first time that I was introduced to the concept, I asked what a lot of other electronics-oriented people do: “where’s the resistor?”

Turns out that it’s a fair question. LEDs aren’t normally driven directly from a battery. And yet (1) people were making throwies with every imaginable color of LED and (2) they apparently weren’t exploding. So what’s the deal?

Continue reading Some thoughts on throwies

Peggy goes wild

The Peggy 2 board is not small by PCB standards, but it was just not big enough for a couple of folks.

MonsieurBon built a Giant LED Board based on the Peggy 2 circuit with a 30 x 30 display area. Here’s his photoset and video on YouTube.


Dave took his Peggy 2 and mounted his LEDs off board for his u:moon project. Here’s the project page and video and photos.


You can read about more Peggy 2 projects in our earlier story, The Peggy Strikes Back.

TGIMBOEJ: One year later

TGIMBOEJ - new logo
One of the big projects that we launched in 2008 is The Great Internet Migratory Box Of Electronics Junk, a pay-it-forward style hardware sharing program for electronics.

Since our original article, TGIMBOEJ (pronounced Tig-Ihm-Boh-Edge) has somewhat taken on a life of its own. In that article, we set up simple guidelines for how to pass the box along, and in the interim we have taken a “laissez-faire” approach, watching and learning from the successes and troubles with that model.

Our mostly-hands-off approach to supervising TGIMBOEJ has worked remarkably well in some respects. There are upwards of 40 circulating boxes now, which have passed through hundreds of hands. And, hundreds of other people have signed up on our wiki site tgimboej.org as potential recipients.

On the down side, the mean free path of many of the boxes has been far too short– some have made it just one hop before stopping.

In talking to folks about the boxes that got stuck, we identified three main stories (all of which point us towards fairly obvious solutions):

1: “I sent it to some guy, but I haven’t heard anything since then.”
2: “Oh yeah– I’ve been meaning to ship it for some time.”
3: “I got this box and I don’t know what to do with it.”

So now, it’s time to get serious. First, we’ve been contacting the last known recipients of the stalled boxes, and trying to get more of the existing boxes back into circulation. Second, we’re relaunching the tgimboej.org wiki site with a wholly new set of participation instructions and procedures.

To keep boxes in circulation longer, we’re now encouraging that boxes should be sent to people who have specifically requested to participate— i.e., people who are familiar with how the project works. We’ve also introduced language in the revised instructions that will guide participants to keep an eye on their box, even after it leaves their hands.

To further alleviate the potential problem of people ending up with boxes but not knowing what to do with them, we’re standardizing the printed materials that go into each new box.

TGIMBOEJ Forms -- low res

Gone are the cute but scrawled little notebooks, replaced by two neat PDF forms– one to log the progress of the box, and the other with detailed instructions on how to participate.

Finally, we’re launching eight new TGIMBOEJ boxes this week, which — along with the others that are coming back into circulation — will help to increase the number and rate of box exchanges.

So now it’s your turn. If you would enjoy trading electronics with like-minded individuals, this is becoming a great time to participate in The Great Internet Migratory Box Of Electronics Junk.

To get started, please read about how it works on the TGIMBOEJ wiki, and if you’re game, add your name to the list of Box Requests.

Meggy Jr RGB Twitter Reader

MeggyTwit - 1
We’ve turned Meggy Jr RGB into a multicolor scrolling LED twitter reader. It’s a handy external ambient data device that displays things recently written by your friends on twitter.

This project was inspired in part by the excellent Twitter LED Scroller by David Nichols. The big idea is that we use a host computer to run a Processing application, which periodically checks Twitter for updates, and then sends “scrolling” data, one column at time, to the external LED display.
Continue reading Meggy Jr RGB Twitter Reader

Evil Mad Scientist Laboratories: Year 3

Evil Meggies

Happy birthday to us! Evil Mad Scientist Laboratories is now three years old.

To celebrate, we’re rounding up our most interesting projects from this past year.

Quick projects and observations:

Magnet tricks
17 cool magnet tricks

moneyDensity.kopi
The monetary density of things

Cheap calendar 2
Cheap Perpetual Calendar

Parts Tray-14
Contact Lens Case Small Parts Tray

Simple LED Projects:

lanterns - 11
Quick, easy, temporary, and beautiful LED garden lights

RoboGames Awards (on)
RoboGames Awards

LED Ghostie
LED Ghosties for Halloween

Food Hacking:

Dry Ice Martini
The Hungry Scientist Handbook

Decoder 2
South Indian Restaurant Menu Decoder

 

"That's no melon!"
“That’s no melon!”

Grillin 2
Hot Dog Bun Grilling Jig

LOLHearts - 34
Improved Custom Message Hearts

Apple Pie
Now that’s an Apple Pie!

Caprese - 16
Eyeball Caprese

Fractal Snowflake Cupcakes - 24
Fractal Snowflake Cupcakes

 

CandyFab

CF6k
The CandyFab 6000

Papercraft

Harley Sleeps
Cardboard Cat Chaise

EdgeLitCard - 49
Edge-Lit Holiday Cards

Hex Boxes5
Hexagonal Stacking Boxes

frabjous - 01
Making a Frabjous

Electronics Projects

Interactive LED Dining table
Interactive LED Dining Table Circuit

 

Color distortion
Giant seven segment displays

DarkPumpkin - 11
Dark detecting jack-o’-lantern

SolarCircuits - 06
Simple Solar Circuits

Soft Circuit Merit Badge14
Soft Circuit Merit Badge

Kit Projects

Meggy Rainbow
Meggy Jr RGB

VideoPeggy - 09
Video Peggy in action

Peggy 2 RGB
Peggy 2 RGB

2313Card - 1
ATtiny2313 breakout boards

Card1.1Top
Revised ATmegaXX8 boards

Crafty Projects

d12 Bag
DIY d12 Handbag (of Holding)

Meggy Jr RGB Cozy-21
Meggy Cozy

no-sew iPhone cozy14
No-sew iPhone Cozy

fabric klein bottle
Fabric Klein Bottle

Seat recovery
Reupholstery with Used Denim

Missile Command Skirt 24
Missile Command Circle Skirt

Fishbowl cat quilt29
Fishbowl Cat Quilt

Maulie-25
Turning Mollie into Maulie

Bicycle lunch bag
Bicycle Frame Lunch Bag

Acrylic Nesting Bracelets-1
Sinusoidal Bracelet Design

Microcontroller Projects

Time exposure
Tennis for Two, a video game from 1958

stockpumpkin - 11
Scariest Jack-o’-Lantern of 2008

mignonette - 09
70 bits of gaming goodness

Serial Port Added
AVR Serial Communication

lissajous-dark - 07
POV Lissajous figures

Mobius Circuit - 21
Single sided circuit board

bulbdial_1
A Bulbdial Clock

Geek Design

Snowflake generator
Vector Snowflake Application

Kindling
The Amazon Kindling

Pi (squared) trivet - 9
Pi Pie Trivet

lego - 2
Lego Kitchen Crafts

Binary Birthday
Binary Birthday

(Whew!)

Basics: Serial communication with AVR microcontrollers

Serial Port Added

One of the distinguishing characteristics of beginner-friendly microcontroller platforms– Arduino, PICAXE, and a few dozen others– is that they neatly wrap up and hide the nuts-and-bolts details of interfacing with the hardware.

Like everything else, it’s a blessing and a curse. The benefits are clear: A new user who has just acquired an Arduino can plug it in, blink an LED, and have a working demonstration of two-way serial communication in just a few minutes.

The drawbacks are a little harder to see. When you just use one line of initialization that calls a “library,” it’s easy to overlook exactly what’s involved: how many lines of code have invisibly been added to your program? What memory structures have been allocated? What interrupts are now going to disrupt program flow and timing? There’s also a portability issue. We often hear from people who got started with Arduino but now want to explore other AVR microcontroller systems, and don’t know how or where to start the migration process.

In what follows we discuss a minimal setup for serial communication with AVR microcontrollers, and give two example implementations, on an ATmega168 and on an ATtiny2313. While this fundamental “AVR 101” stuff, we’re approaching the problem (this time) from the migration standpoint. Suppose that you had an Arduino based project, where you relied on serial communication– using the library functions–between that hardware and your computer. From there, how would you migrate to a stand-alone AVR microcontroller with similar functionality, or even to a different microcontroller?
Continue reading Basics: Serial communication with AVR microcontrollers

Soft Circuit Merit Badge

Soft Circuit Merit Badge15
The proliferation of spoof, nerd, science, and electronics merit badges has demonstrated that geeks like to show off their skills and accomplishments. One skill is particularly appropriate for the format: soft circuitry. By building your own soft circuit onto an actual badge you can demonstrate your mastery.

Soft Circuit Merit Badge14
The size of the badge is just right for a simple circuit with a battery, a switch and an LED. The crowning touch is that the stitched circuitry can form the circuit diagram as well.

Continue reading Soft Circuit Merit Badge

Peggy 2 RGB

Peggy 2 RGB
We filled up a Peggy 2 with 2×2 super-pixels consisting of red, green, blue, and white 10 mm LEDs. This makes an easy and big programmable full-color LED matrix.

Peggy 2 RGB
Peggy fits 25×25 LEDs, so if you fill every hole this way, you wind up with a 12.5 x 12.5 pixel RGBW matrix.

And like whoa— you can animate it.

Peggy 2 RGB   Peggy 2 RGBPeggy 2 RGB   Peggy 2 RGB

Yup, there’s video. The video is embedded below, and you can also view it directly at YouTube. (In either case, please excuse the scanline artifacts produced by our camera.)

One thing worth noting (and that we demo in the video) is that you can diffuse the big RGBW pixels into one continuous full-color display by placing a thin diffusing plastic layer above the LEDs– it really works well.

The demo code is an Arduino sketch, based on Jay Clegg’s timer-interrupt style grayscale driver for Peggy (demonstrated here), you can download it here (12 kB Arduino .pde sketch file). Besides the colorful flow shown in the pictures, this code also has a mode to light just the red, green, blue or white LEDs at a time.