I have an automotive DMM with an inductive clamp to clamp a spark plug lead to measure RPM of an internal combustion engine. I want to measure the RPM of some small DC motors with and without gearboxes. Range up to about 3000 rpm. I was wondering what would be the simplest way to do this. Perhaps a tiny strong magnet attached to a tooth of the sprocket I want to measure? I was thinking about a small coil near the spinning magnet and clamping the wire in this continuous loop, but then I wondered if I set the sprocket up to rotate between the open jaws of my DMM's induction clamp, would this likely give me a result? I realise that I should try this to see, but as I'm not able to get to an electronics shop to get magnets etc for several days, I want to try to find out more of what I should buy when there. Someone suggested a Hall Effect switch, but I have no idea how to set this up for my meter to read RPM. Thanks in advance for any help in this area.
- posted
17 years ago