Interfacing Your Laptops Onboard I2c


[ladyada] ran across this excellent hack by [phillip]. Apparently there’s a clock, data, 5v and ground connection available in most modern video connections. (He even notes HDMI cable pins) He wrote some drivers and can now control i2c hardware directly from the PC Mac. [Ladyada] notes that most laptops use an i2c bus for extra sensors as well. For now, the code only works on Mac OS X.

Smart Car Sensing With RF


In order to tell his home automation system that he’s home, [Jim] mounted a RF transmitter in each of his cars. When the car is on, the transmitter is powered up. The house picks up the transmitter signal when the car arrives or departs. With that information, he was able to set up some stateful rules that can be activated when people arrive or depart. Some people prefer to use APRS and read vehicle location from the transmitted GPS coordinates, but this is a bit cheaper and doesn’t transmit your position to the entire world all the time. The useful range is about 100 feet, so this can work even if you have to park in the street.

Human Sync Optical Tachometer


[Jared] sent in this optical tachometer by [Mike Freeman]. The write-up and code requires a free registration, but if you’ve got a use for it, it’s probably worth the hassle. The zip archive includes a nice writeup in PDF format, and the code needed for the pic controller. The tach was built specifically for model helicopters. The user looks through the viewfinder and adjusts the pot on the side until the spinning helicopter blade visually stops turning.