In the kit you get the parts to build your own Bristlebot, a tiny robot made from a toothbrush: (consists of toothbrush, pager motor, battery, and foam tape)

and LED throwie art: (consists of two color-changing RGB LEDs, battery, and a magnet)

We’ll have a Bristlebot [...]]]> http://todbot.com/blog/2010/03/07/bristlebots-and-led-throwie-art-at-crash-space/ (as a few had noticed, I had an error in the schematic shown. It’s been updated, thanks!)

A recent question from a friend who made a really cool BlinkM hoodie was: How can you turn a momentary button press into an on/off toggle?

There are tons of ways to do this if you like getting into electronics. Most all work off of some flip-flop like principle. And while I could have suggested a true flip-flop chip, I thought it would be cooler if you could use a 555 timer chip (which contains a single flip-flop and a couple [...]]]> http://todbot.com/blog/2010/01/02/momentary-button-as-onoff-toggle-using-555/ One of the challenges of working with I2C (aka “two-wire” or “TWI” or “Wire”) devices is knowing the I2C address of the device. Older devices have a fixed address, or a “choose one-of-four” approach. But newer I2C devices have fully programmable addresses, leading to cases of not knowing what address a device is at.

Fortunately, there’s a technique one can use to “scan” an I2C bus and determine these addresses. Conceptually it’s very similar to a network “ping”. Below is an Arduino sketch “I2CScanner.pde” that turns an Arduino into an I2C bus scanner.

- I2CScanner.pde — Turn Arduino into [...]]]> http://todbot.com/blog/2009/11/29/i2cscanner-pde-arduino-as-i2c-bus-scanner/ [This post was part of a CrashSpace mailing list discussion on a "proximity t-shirt": a shirt that would light up or similar when other similar t-shirts were nearby. People were wondering how good RFID was at localized detection of tags.]

Okay so I’m a big RFID nerd, did a lot of consulting work using it. So here’s a quick brain dump.

Regular passive RFID is designed for identification not localization. The RFID tags can be reliably read only to within a few centimeters. But the readers are cheap. You can get 128kHz (LF) and 13.56MHz (HF) RFID [...]]]> http://todbot.com/blog/2009/11/19/too-much-rfid/ If you want a slightly different look for your Halloween pumpkin or skull, you can pretty quickly whip something up with a few servos and an Arduino. Here’s a set of Scary Shifty Servo Eyeballs, for instance: It looks around randomly…what’s over there!… wait, what’s that!

As you can probably tell it’s a pretty simple arrangement (click for bigger):

It consists of the following components: - 2 toy eyeballs or ping pong balls painted like eyeballs - 2 small servos (HXT500 from HobbyKing.com or similar) - 1 standard servo - 1 Arduino with tiny breadboard rubber-banded on top - 2 BlinkMs, one for each [...]]]> http://todbot.com/blog/2009/10/07/scary-shifty-servo-eyeballs/ This is one of the greatest bits of youtubery I’ve ever seen, and I generally dislike auto-tuned stuff. Carl Sagan’s Cosmos was one of the most important things to happen to me as a child. This video & song gives me the shivvers. And makes me miss Sagan all the more.

I love the song’s chorus created from cut up Sagan quotes: A still more glorious dawn awaits Not a sunrise, but a galaxy rise A morning filled with 400 billion suns The rising of the milky way

(via jwz)

When I first started with Arduino, I thought Serial.available() was a very loose wrapping of the RXC bit in the USCRA register, i.e. if I didn’t get data out of there fast, it’d be gone. That led to convoluted code like:

Yuck. So you end up designing protocols that are too terse. Or maybe you think you need to [...]]]> http://todbot.com/blog/2009/07/30/arduino-serial-protocol-design-patterns/ I recently got a case for my iPhone and it’s the kind that precludes the use of the dock. I kind of like the dock concept, but instead of taking a Dremel to the existing dock, I spent a few minutes drawing up a replacement that could be cut from acrylic scraps on the laser cutter. Here’s the result: (click for higher-res)

It is made of four slices of 1/4″ acrylic (actual width 0.22″). The top two slices have an oval opening just snug enough to fit the ipod connector and keep it in place with friction. [...]]]> http://todbot.com/blog/2009/07/15/quickie-laser-cut-iphoneipod-dock/ I have one of those USB-based logic analyzers that needs Windows software to make it go. I had been doing Windows-in-a-window with VMWare, but it’s kind of a pain. If I were to use a real Windows laptop, I’d need a shelf or something for it. I wanted it above my oscilloscope, which meant a laptop stand that was taller and wider than most. Time for the laser cutter!

(click for larger)

My design requirements were: - assemble without any tooling or fasteners - fit on a single 1′x2′ sheet of the 1/4″ plywood I already had - be stable enough [...]]]> http://todbot.com/blog/2009/06/16/laser-cut-laptop-stand-and-oscope-hugger/ Or: A good use for old Arduino boards

Like me, you may have a few old Arduino boards or ATmega8 chips (in the boards) laying around from when you were first playing with Arduino. Those chips can still be really useful as the heart of a tiny “Minimal Arduino” setup.

A normal Arduino board contains support components that make it easy to use. If you want a smaller footprint, you can get one of the many Arduino work-alike boards. But if you want a really small footprint, and reuse your old parts, you can make an Arduino board using [...]]]> http://todbot.com/blog/2009/05/26/minimal-arduino-with-atmega8/ I’ve been working with a super minimal Arduino setup recently. After seeing Alex’s awesome Arduino/ATmega breadboard header, where he notes there’s no room on the PCB for pin labeling, I wondered if it would be possible to make a small sticker that goes on the ATmega chip, labeling the pin names.

Here’s my first attempt:

And in use:

This was created by printing on a full-page sticker then laser cutting it to shape. I could have also just cut out the sticker with scissors, or used regular printer paper and double-sided tape.

Some files if you want to try this out [...]]]> http://todbot.com/blog/2009/05/23/arduino-chip-sticker-label/ A single BlinkM MaxM can easily drive a 5 meter (16 ft) roll of the flexible RGB SMD LED tape that’s used for architectural lighting. Each roll contains 150 RGB LEDs.

Each LED in the tape is a SMD RGB "5050" LED, capable of putting out about 6000mcd. The spacing between LEDs is 3.3cm (~1.25").

Every 3 LEDs is a cut mark with solder tabs so you can cut or join pieces of tape.

Max current for a 5m roll is about 1.9 Amps. I did a quick test of MaxM driving three rolls at about 6A and [...]]]> http://todbot.com/blog/2009/05/21/using-maxm-with-flexible-rgb-tape/ BlinkM MaxMs will be back in stock soon. Over on our GetSatisfaction area, there’s a question on how to use multiple BlinkM MaxM “Blaster” LED boards with one MaxM “Master” driver board. It’s possible and only just a little tricky. The Blaster board is powered by the 5V voltage regulator built-in to the Master board. That regulator is designed to power just one Master and one Blaster. If you try to drive multiple Blasters with it, it might work, but we don’t recommended it and could blow up your Master board.

Instead, it’s better to drive [...]]]> http://todbot.com/blog/2009/04/12/multiple-blinkm-maxm-blasters-on-one-master/ I’ve been exploring various types of gearmotors. DC motors by themselves spin too fast and have low torque. Gearmotors are motors with a gearbox that slows down the high speed of the motor and produces higher torque. Most gearmotors are pretty expensive though. I want a really cheap, almost throw-away, source of gearmotors. It turns out cheap servos can be made into continuous rotation gearmotors.

Modding servos for continuous rotation is not a new hack. You can find many examples of it. You can even buy a nice continuous servo made by Parallax. But [...]]]> http://todbot.com/blog/2009/04/11/tiny-servos-as-continuous-rotation-gearmotors/