Hall Effect sensor: proximity-motion?

Hi everyone,

I just ordered some Hall Effect sensors (ALLEGRO MICROSYSTEMS A1302KUA-T) but I am not sure whether they can just act as on-off switch or also as priximity sensors. I need to measure the distance of a moving piece of metal (where i would screw a magnet) while it is moving.

ps: if you want to know what's this is all about. I am just trying to figure out a way to attach a sensor to a bathtub mixer.. after trying (and failing) the potentiometer way i thought it could work measuring the moving distance of the screw which is inside the tap, the one that change the water pressure inside..

thanks a lot!

Yes if you wire the output to the analogue input you can read how strong the field is:-
http://www.allegromicro.com/en/Products/Part_Numbers/1301/

However, remember a magnetic field drops off as the cube of the distance so the range is not too great.

The A1302KUA-T does output a analog voltage proportional to the strengh of the magnet field it is sensing. A3213 and A3214 sensors are on/off magnetic sensing switches.

Lefty