Basic Pulse Wheel

Going a mite bit more complex this week... This is a basic pulse wheel for DIY projects. These little guys are commonly used in electronics to detect the velocity and direction of rotational motion without inserting drag or friction into the system, like a roller detector would cause. You simply shine an LED, laser or other light source through the slits on one side of the wheel and detect it with a photosensor on the other side, and then send the pulses to whatever you need to do detection and analysis. You can even detect direction of rotation by using two detection sensors and comparing their outputs. This is exactly how old school trackball mice did their magic, and the method is still widely used today in a myriad of machines of all kinds.

The disc diameter is 30mm, the slits are 1mm wide, the center hole is 3.2mm, and the disc thickness is 3mm. I made the center hole 3.2mm to compensate for print inflation. In practice, printed in PETG, this thing spins very nicely on a #4 mac