N-JABS N-JABS is Not Just Another Brick Sorter - it's a colour brick sorter. The device cycles between shining red, green and blue light onto the brick whose colour is to be established. From the relationship between the amounts of reflected light with each different incident colour, it is readily able to distinguish between different colours of brick.
	With the model disassembled, we can see how the RGB light filter works. During operation, there would be a torch beside the motor pointing towards the brick through the filters. The acetate filters I used are quite thick, but can just be seen between the two black beams opposite. The motor drives a rotational sensor and also moves the filters left and right by a rack which is driven by an elastic band. The model "knows" which filter is in front of the torch by the angle represented by the sensor. The inset is a light sensor, which points at the current brick in the chute. It is mounted on a turntable so that it can be pointed at 45 degrees to the surface of the brick.
The gripper is opened and closed by a micro motor (the red brick in the middle). This simply drives two wheels by an elastic band. This removes the need for a sensor to establish wether the gripper is open or closed; overrun is unimportant, because the band just slips. The whole mechanism is mounted on a tank-like turret which, along with a rotation sensor, is driven by a worm-gear.

Here is some NQC 1.x code which can continuously sort between black, blue, red, yellow and white bricks and dump them in matching piles. There is also a pile for bricks of undetermined colour, but <smug grin> there are rarely any bricks deposited here.