Recently we suspected that one motor of our hexacopter had been damaged in a crash. Since removing the motor requires almost the complete disassembly of the copter I started thinking of ways to test the motor in place.

The idea of using a laser and a photodiode came pretty soon. But there were a couple of small details, that made the whole setup very simple and efficient.

 

(more…)

As part of a sleep phase monitoring alarm clock, i was looking at different ways to track my movement during the night. The sensor i finally settled on, was a homebuilt pressure sensor made from aluminium / tin foil, an anti-static bag and foam rubber. There are similiar sensors already described on various pages. However these are either rigid (using copper board) or use conductive fabric, which can be hard to find. The nice thing about this sensor is, that it is rather flexible, thin and has a wide range of resistance. Distadvantages are the large drift over time and variance between different sensors. (more…)

This is a circuit board for the vusbtiny programmer from Chris Chung. The circuit is based on a attiny running V-USB  to present itself as an avr programmer to the host. I only modified his circuit marginally. The main goal was to make the circuit as small and cheap as possible. The final dimensions are 28mm x 12mm, with 10mm x 12mm taken up by the USB connector. I also have a second untested version with a footprint of 16mm x 12mm.

(more…)