Are you extremely stylish? But afraid to get lost in the forest while picking mushrooms? Well, this is exactly what you need! If to be more serious, this is small project to get more familiar with electronics: arduino, sensors, actuators and coding. I decided to fabricate bracelet witch’s strength of light depends on compass position. More north it is directed – brighter it shines.

The main component for this application is tilt compensated compass moduleCMPS10. Also I use ‘arduino fio’ (3.3V), which is smaller than classical ‘arduino uno’ and adapted for lithium lon battery. It can be charged using usb cable. To illuminate bracelet panel  I got 3 high luminosity, white diffused leds’.

Here are some core hints:

• For this application input was tilt compensated compass (CMPS10), outputs were 3 high luminosity leds.
• First prototype was made on breadbord to check how it works and to program arduino fio.
• To make it portable the circuit had to be replaced and soldered on smaller breadbord.
• There were few tricky moments: first of all, because of different voltage, leds didn’t want to shine enough bright. Transistor, which was helpful using power supply from computer appeared useless with lithium battery. The circuit was effected by removing it.
• Reflecting tape was used to increase brightness of leds. But everytime I sticked tape on panel, leds used to stop lightning. It appeared that tape worked as well as the conductor. To solve it I put some extra isolation on metal parts of leds.
• I had to change some components’ positions and cut out part of bread bord to place everything into the box. And finally it worked.
• Arduino fio doesn’t have usb port for programming. It requires special cable with pins.

here and here you can find full documentation of project