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Topic: Hall effect sensor (Read 994 times) previous topic - next topic

retrolefty

Keep in mind that hall effect sensors come in many flavors and which you are working with must be known to figure out how to use it. Some kinds I have seen.

Digital output, non-latching, magnetic polarity unsensitive
Digital output latching based on magnetic polarity and value above a given switching point
Analog output voltage proportional to Gauss strength of a certain range/sensitivity.

Many of the digital ones require you supply a pull-up resistor to work (open collector output)

So without a true part number/datasheet you can still get tripped up trying to use it properly.

Lefty


crazypj

I've hooked it up and it is 'normally ON' (getting 4.85v out)
When I put a magnet on it output drops to zero.
I was using the 'wide' side of trapezoid (thanks for reminding me  ;) )
I'll try putting magnet on the 'narrow' side and see if I can get it to swich with a gap instead of touching
At present I'm using a 3/16"x 1/16" thick neodymium magnet but really think I need a larger size to give 0.040" airgap instead of contact
I'm not a complete idiot, but, I'm working on it

dc42


I've hooked it up and it is 'normally ON' (getting 4.85v out)
When I put a magnet on it output drops to zero.
I was using the 'wide' side of trapezoid (thanks for reminding me  ;) )
I'll try putting magnet on the 'narrow' side and see if I can get it to swich with a gap instead of touching
At present I'm using a 3/16"x 1/16" thick neodymium magnet but really think I need a larger size to give 0.040" airgap instead of contact


Try the magnet both ways round. Also, some sensors need to see one pole of the magnet to turn on, and the other pole to turn off.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

crazypj

I believe it's non-latching as it doesn't need magnet reversed to turn back on (is that a correct assumption for latching and non-latching?)
It will work with magnet 'upside down'
I used a compass to find out which is North pole of magnet, I had been using South pole
Sensor works with either but does seem more effective on North
I have an freind/aquaintance who is an electrical engineer (one of his several degrees  :smiley-roll-sweat:)
Saw him this evening and asked if it actually matters if you switch Hall effect sensor with North or South pole of magnet.
Liked the question but didn't have an answer (not sure if it was because of spending all afternoon at a brewery?  :D )
I'm not a complete idiot, but, I'm working on it

dc42

Some digital hall sensors need alternating poles, some are Unipolar (sensitive to one particular pole), and a few are ominpolar (equally sensitive to either pole). A unipolar device may sense the "incorrect" pole if it is presented somewhat off centre.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

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