The speed range is between 200 RPM - 3000 RPM, updates I would like every second (not over done but still pretty fast to changes in regards to human sensing ability; that information will be exported to a display. So HALL effect is something I'm going to investigate any suggestions of where to start?
Nothing else requires angular precision that the encoder will provide.
Thanks again for the feedback
At 200 RPM the effect on update time will probably be due to the time necessary to make the calculation, probably not very long. At 3000 RPM, the calculation is likely to take longer than one revolution but still not likely to affect update times. What you need to evaluate carefully is how the different ways to sense the time of a revolution will affect the entire system. For example, if you choose to sense the speed sensor via an interrupt service routine... tempting... then you need to think about what effect higher RPM will have on the calculation/update times.
I would start with a search for Hall effect speed sensors that are easy to mount and designed to sense in a way practical to your application, maybe one designed for an automotive application. For example, some Hall effect sensors are designed to sense a projection like a gear tooth or an embedded rod or a depression like the slot for a set screw. That type is sometimes referred to as magnetically biased. Others are designed to sense a magnet somehow placed on the rotating part... maybe not so practical. I wouldn't necessarily rule out variable reluctance pickups as they usually have a threaded mount and are easy to adjust. Conditioning their output can be easily done with an analog comparator, sometimes one of the included peripherals of your microcomputer.