I've been working on the little rotary encoder gadget that I took along to last month's Dorkbot Bristol. It's a CD-ROM hub/motor, stripped out of a broken drive and repurposed. I've wired up the three hall-effect sensors to give a signal that represents the rotation of the hub, and connected it all to an Atmel AVR ATmega8 microcontroller. I've ( Read more... )

I showed off a little circuit at Dorkbot that I'd made up on a breadboard. It's basically just a brushless DC motor from a CD-ROM drive, hooked up to three comparators and some LEDs. The three hall-effect sensors in the BLDC motor generate about 150mV, and change polarity as the motor is turned by hand. This makes a contactless rotary position ( Read more... )