How does a magnet on the axis of a shaft operate a Hall-effect sensor?
winchman
Posts: 22
I'm looking at the RPM indicator here:
http://www.parallax.com/html_pages/robotics/machining/RPM_display.asp
The photos show the button magnet in a holder so it's right on the axis of rotation, and the Hall-effect sensor is mounted directly above it. The poles on button magnets are usually on the flat faces. How does the flux change if the same pole of the magnet is always facing the sensor and always the same distance away?
Is it a magnet with the poles on opposite edges, and the sensor is really a little off the axis?
Roger
http://www.parallax.com/html_pages/robotics/machining/RPM_display.asp
The photos show the button magnet in a holder so it's right on the axis of rotation, and the Hall-effect sensor is mounted directly above it. The poles on button magnets are usually on the flat faces. How does the flux change if the same pole of the magnet is always facing the sensor and always the same distance away?
Is it a magnet with the poles on opposite edges, and the sensor is really a little off the axis?
Roger
Comments
The polarity of the magnet shown isn't mentioned, but I can tell you this. Round (disc) magnets are available in three different polarities: face, edge and radial. Additionally, some Hall Effect sensors are polarity sensitive, and some are not. Those that are not, only need the presence or absence of either polar field in order to sense it.
I don't know if that helps or not, since I was unable to see exactly where the Hall Effect sensor was in those pictures - sorry.
Regards,
Bruce Bates
and all will become clear.
http://www.allegromicro.com/sf/0610/