[jonboy]

We had an off season activity to demonstrate feedback to control the speed of a CIM and needed a sensor to sense shaft speed. It was canning season so I got a canning jar lid, removed the rubber sealing matl, hammered it flat, drilled a hole in the center, and put 8 notches in the edge with a paper hole punch. Mounted the lid on the CIM shaft with hot melt glue. Got an opt switch out of a printer, mounted it on a vector board with two resistors and connected it up to the DIO. See pic attached. Has worked fine for months and is a great way to demonstrate feedback control to our team. Worked like a charm. Compact, lightweight, very low cost, ultimate in recycling/reuse...