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curious1
04-10-2007, 10:15 PM
The melexis hall sensor for rpm sensing on the example milling mach. appears to be directly above the magnet which is lying flat on centerline with the spindle. How does it sense changes in the field ?
The data sheet for the sensor shows no such arrangement.
It's not exactly clear where the sensor is mounted in relation to the magnet on the mill.
Also, how would adding another magnet increase resolution and where would the second mag. be placed in relation to the first one ?
The link to the mill is in the Parallax ad for the hall sensor as well as the data sheet.
Thanks

Ken Gracey
04-11-2007, 01:06 AM
The Melexis sensor is able to perform two functions. First, it can be placed directly over a magnet and detect the change in poles. With each rotation the pin is high (or low, I don't remember). Additionally, the sensor can be used to count pulses from a magnet rotating by the sensor. In this example the magnet would be mounted on a disk or something similar.

I haven't looked at the datasheet recently, but when I built the project it described how to place the sensor directly over a rotating magnet.

Ken Gracey
Parallax, Inc.