please see the image below in reference to a cheap compass. I'm not an electronic engineer so pls bear in mind
the idea is to create cheapest form of electronic compass. it will be in-accurate by about 15degrees, slower than gyro ones, and need to be held flat like a compass. Whats wanted is cheap + general direction according to 8 co-ordinates.
just like with normal compass, its bar rotates on a pin. the bar is fixed to a black card (thin, light, black about 200gr/gsm card). A slot in the card to allow IR light to pass through for the photo interuptors. depending on the cards rotated position, 1 or 2 photo interupters would be postive (passing IR light through the slot. With each photo interupter connected to an MCU pin each, could calculate the position......