"vey" wrote in message
...
It is a hall effect magnetic proximity sensor.
Here is the data sheet:
http://www.datasheetarchive.com/preview/3528026.html

I tried putting an ohm meter on it, but a moving a magnet
around it
doesn't make it change.


ther maybe a way the experts know
but according to datasheet you would want to apply 8-12 v on pin
one and expect to see output on pin 3 at 2-5v depending on Gauss
applied