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UGN3503UA Hall-effect sensor

Hall_Effect_Sensor.pdf183.06 KB
Vendor's Description: 

This little fellow detects magnetic flux and is dead simple to connect up, just 5V in and an analog output. Can be bought at most places selling electronic components. I bought mine at  http://www.futurlec.com/index.shtml

I've posted a walkthru on using this as a positional sensor but it can be used as a gear tooth sensor or notch sensor in steel parts. See the attached datasheet for specifications and suggested uses.

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Does this sensor go by any other name? I was hoping RadioShack carried them since I have a coupon to use from there.
All the sensors mentioned here are "hall effect sensors". Various makes and models will have different built in amplification circuitry but they all work in the same basic manner.

I've seen it mentioned that these might be a poor-man's compass which got me to thinkin'... If these things can detect the Earth's magnetic field, it would probably be able to find say, a few rare-earth magnets stuck together and placed across the room in a corner. I'm sure the unit shown above might not be the right one, but there have to be some super sensitive ones. Also, any thoughts as to directionality? Can you put one of these on a servo to sweep for the strongest signal? The magnets in the robot's motors will probably confuse it, huh? I dunno, I'm just thinking out-loud...



Hmm, the magnets inside the motor are usually aligned such that the field around them is kept pretty tightly packed, so a little spacing should be enough to avoid interference.
Unfortunately the same can be said about your magnets - they'll tend to keep their magnetic field wrapped tightly around themselves, so it'll be hard to detect at a distance. You might have better luck using a Halbach Array, which creates a stronger field on one side of the array by depleting the field on the opposite side. Range is still going to be a serious problem though.
The reason the Hall effect sensor can pick up the earth's magnetic field is that we're inside it. Earth is a very big but very weak magnet. Rare earth magnets are pretty small, but have a much stronger field. Unfortunately the field size is basically tied to the physical size of the magnet =/

I've just been to an electronics store and I was told that this sensor is NO LONGER IN PRODUCTION :(

Any suggestions as to what I could buy instead?

EDIT: The thing is..I'm not entirely sure which sensors produces an analog signal (like I need) and which simply go on/off.

How about this one: A1323LUA-T 

It would seem to be what I need?!

The A1323LUA-T is a good equivalent, works at 5V with an output that is half of the supply voltage when no magnetic field is present. If you can get the A1321LUA-T it has twice the sensitivity @ 5mV per Guass.

However I also asked around for this one in the meantime and I don't seem to be able to buy it here. So I'm sorry to bother you again but I'd like to know if one of these would do the trick:




These may be the only analog hall effect sensors I can buy around here. But they seem rather different. For starters they have 4 legs instead of 3?!

It's not cause I'm too lazy to read the datasheets myself it's just that I'm not much good at it. However I did notice that their sensitivity (min-max) respectively are: 13-19, 3.2-4.8 and 1-2.

I presume higher is better (and probably more expensive)....

I'm sorry but I don't know what kA/m is. I think you will have to experiment with them. The two outputs are not a problem, the output is the difference between the two. This is a better setup for connecting to an op-amp. Here is a circuit that will amplify the sensor output by 100. Changing the 2x 100K resistors to 2x 50K you would change the gain to x50.



Just one more thing...in this thread you posted a circuit for the A1323LUA-T, with 4 sensors + 2 op amps (2 sensors connected to each op amp). If I use a KMZ10 instead (for a compass) will I need 2 or 4 of the circuits above? Say 4 sensors + 4 op amps or 2 + 2 ditto? Or...?

Strike that!! In the meantime I found out 2 things: the KMZ10 costs around 10$ and I found a place to buy the UGN3503UA for around 2.5$ (after checking around 25 shops). So I'll go for that. I suppose the circuit you posted here would also apply to the UGN3503UA....

Thanks again :)

you will need to experiment a bit, particulary the calibration.