Tachometer Kit

[Kennyd]

I'm using small rare earth magnets I got on sale. I imagine HF carries them. They are only about 5/16" in diameter, but plenty strong.

I don't really know what the requirements are in strict terms.

OK thanks, how about the sensor that I asked about?

 

[Hawkeye]

The Hall sensor specified in the MachTach manual is SS41 (Digi-key 480-1999-ND) I got the same one at my local electronics wholesaler. Fairly common. Data sheets available on line.