I would like to build a tachometer for a spindle motor. Where I am struggling is how to sense the RPM. The two methods I have come up with so far is Hall sensor and a laser (which I am not even certain I can do).
Both have downsides. The advantage of a Hall sensor is it is fairly straight forward and easy to implement. The downside is there will be weight (the magnet) on the spindle shaft and I am concerned that will throw off the balance. The motor will only be spinning at most 40K RPM. Do I need to even be concerned about that small magnet causing an issue?
A laser has the advantage of having virtually no weight on the spindle other than the target material. But much more complicated than the Hall sensor option. More important it could present a safety issue, especially since the device would be permanently mounted.
Any other ideas on how to do this?
Both have downsides. The advantage of a Hall sensor is it is fairly straight forward and easy to implement. The downside is there will be weight (the magnet) on the spindle shaft and I am concerned that will throw off the balance. The motor will only be spinning at most 40K RPM. Do I need to even be concerned about that small magnet causing an issue?
A laser has the advantage of having virtually no weight on the spindle other than the target material. But much more complicated than the Hall sensor option. More important it could present a safety issue, especially since the device would be permanently mounted.
Any other ideas on how to do this?