Michael Ang

The mission of Habana Labs in Brooklyn is to research, develop and apply technology related to ecology and sustainable energy. Their focus is on empowering local communities to take part and their approach is very hands on. At their third in a series of workshops on wind power the focus was on the electronics needed to convert kinetic motion (e.g. from a wind turbine) into useable electrical energy. Using mostly scavenged motors about 40 people were able to build small generators to convert rotary motion into electricity. Felt really good to see people getting their hands dirty and sustainable energy becoming less abstract.

There were a lot people taking pictures, including a video crew from ITP. There should be more documentation documentation up on their site soon.

Habana Labs Flickr photoset

My blue flower will use inductive charging. I took apart an Oral-B CrossAction Power Max toothbrush ($18 at K-Mart) to see how it works and see if it would be useable in my project.

Charger hacking and coil construction pics

The toothbrush side is remarkably simple. There is a coil attached directly to a battery (no rectifier) and a switch which physically connects and disconnects the battery from the motor assembly. The motor appears to be similar to that used in a pager. The attachment on the shaft has an inverted cone offset from the axis of the motor that loosely connects to a metal rod that goes up to the toothbrush head. The design is very elegant, using a minimum of parts and materials.

The base is completely filled with an epoxy or rubber (finding epoxy is the hacker’s worst nightmare!) There is a circuit board that I didn’t free from the epoxy and coils of magnet wire. The magnet wire is formed into stranded wire and then coiled (as opposed to a simple bobbin of magnet wire). The base seems more or less useless for hacking because of all the epoxy. Interesting to see that the shape of the coil is pretty loose.

For my own inductive charger experiment I used 22ga magnet wire on a spool as the primary and 30ga magnet wire coiled around a screw as the secondary (in a transformer, power is transferred from primary to secondary). Using about 0.9 amps at 8V and 5.4kHz I could get an LED to light at 2.6V. There seemed to be a voltage peak at that frequency with this arrangement. The primary had an audible whine, which isn’t too surprising. Now the trick is to figure out the most suitable combination of coil geometries, drive frequency, drive voltage, and core type to get the power I need.

For Living Art week 3 we’re are supposed to implement a Finite State Machine in a physical system. Suzan and I are hacking a Gloomy Bear to add some interaction. I’ll describe the interaction later (should be fun), but here are pictures from the Gloomy Bear hacking session.

The voice recorder we got from Radio Shack works well when powered from the NiMH battery pack and attached to a larger speaker (the built in one wasn’t loud enough). The problem is that the recorder loses the recording when you turn it off and only gives you a single recording. We could build a battery backup circuit but instead we’re going to try a Winbond ChipCorder which will give us multiple non-volatile recordings and direct microcontroller control.