This moisture meter was based on a circuit from Forrest Mim’s excellent “Getting Started in Electronics” book. It uses an Ampere meter (not pictured) via a amplifying transistor to display the conductivity of the soil in a planter. And it works! This setup may be the basis for our primary plant sensors for ITPlant.

Samtec will sample small quantities of parts (usually no more than 10 of each. However their web site is confounding. If you want to find a part number, request or download a catalog first. When you are ready to order, use the Samtec Sample Form Put in the Item number and Quantity only. You don’t

May 15, 2007: Apparently the AT commands for the BlueSMiRF radios are a trade secret. BlueRadios requested that they not be posted. So, uh, don’t use them I guess? Here’s the AT command set for BlueSMiRF modules. It’s tremendously handy to know all this stuff when working with the modules. I had high hopes that

At ITP on Thursday evenings, students teach students in hour-long sessions that we call DriveBys, because a lot of knowledge gets sprayed into the crowd in a short period of time. I just did one on the XBee ZigBee radios, covering the basics of applications, comparisons to other technologies, how to make one, advanced projects

For Project Development Studio I’m working with Kate, Rebecca and Kati on a project to create an interaction network between live plants and people. Here’s our ITPlant notes.

Matt, Teresa and I built a full-scale Stirling engine for use as a power source for a future mechanical computer. Stirling engines are external combustion engines. This one will derive its power from pressure differences created by the exchange of heat between hot and cold water compartments. We’re a bit concerned that the crankshaft may

Matt, Teresa and I created a paper clock from a kit using X-Acto knives, white glue and human tears. While the tolerances weren’t close enough for it to actually keep time, we learned quite a bit about the internal mechanics of timekeeping, and spent 20 happy hours together in the Physical Computing lab. Clocks rock.

After Dark Whimsical toasters Tile Toy Modular interaction Element Good lookin’ objects X10 Home automation

9/20. Define project precisely. How many behaviors per object, how many objects, what behaviors, what variables, how communications will work… 10/4. Interactions chosen, Objects chosen and roughly illustrated. 10/18. Prototype of objects and interactions ready for initial user testing. 11/1. Engineering for networking completed. Robust communications. Draft CAD drawings for objects. 11/8. CAD of objects

This UV warning card has only a nominal cost, and could help alert the owner to potentially nasty sunburn danger. An electronic version could be incorporated into clothing, maybe with a visual and audio signal once too much exposure has occurred. The two parts of this concept are already out there. Here’s a solar exposure