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Anyone have experience with analog Hall Sensors?
11-16-2017, 11:11 PM,
Anyone have experience with analog Hall Sensors?
I'm in the initial prototyping stage for a little hobby project where I need to be able to detect several different objects in near proximity to several sensors. For cost and durability purposes I was considering using some small neodymium magnets in the objects and linear (analog) Hall sensors for detecting their presence. NOTE: My electrical skills are middling at best.

So my question is: if I have several objects that hold their magnets at the same distance from the sensors and I rotate the magnets in each of these objects, can a reasonably-priced (under $10/ea) Hall sensor detect the difference in rotation of the magnets with sufficient resolution to be able to correctly identify each piece by the voltage it produces from the sensor?

11-17-2017, 09:11 PM,
RE: Anyone have experience with analog Hall Sensors?
Good to see you back on here!

I've done very little with Hall Effect sensors.  But, I have built two of these: http://zeltom.com/products/magneticlevitation
I can tell you that the Hall Effect sensor will pick up a small neodymium magnets several inches away, and these sensors are well under $10.  The resolution is good enough to be able to adjust the electromagnet to keep the magnet suspended in air.

By "rotation of the magnets", you are describing the magnets rotating around what they are mounted on, correct?  In other words the axes of rotation is external to the magnet (like Earth orbiting around the Sun), not a magnet spinning around an axis through the magnet (like Earth spinning on it's axis)?  If you have a quick sketch, that may help.  Depending on how your objects are rotating, it may require two sensors per on if you want to detect rotation beyond 180 degrees.

With the Hall Effect sensors I am using, I believe there is a way to configure them to do what you desire.  The sensitivity and resolution would support it, provided the proximity, etc. were designed properly.  I'll look around to see if I have any extras around.  I know I originally bought more than two.

"I built it because I didn't know I couldn't"
11-18-2017, 06:59 AM,
RE: Anyone have experience with analog Hall Sensors?
I'd second N8's comments.

I know that they have hall sensors that have sufficient resolution to use as encoders on servos. Your application seems similar to this, ie, you want to detect the rotation of a magnetic field and use that measured angle to make a determination of what piece it in proximity to the detector.

Some things to consider.

Hall sensors measure field strength
Field strength is going to vary with distance.
Rotation of the magnet is seen as a varying field strength and also a change in polarity
Field strength changes due to distance and rotation are essentially indistinguishable

If you can control for the factors that affect field strengths, you should be able to accomplish what you would like to do.

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