Hall Sensor identification.

I pulled these hall sensors out of a cdrom and floppy drive and am having a hard time identifying what they are. The only markings on them is an "E" which doesn't really tell me anything (manufacturer, maybe?). If anyone can tell me a P/N or who makes them or point me to a datasheet that would be great.

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**broken link removed**

A couple of years ago, I really found a good description on how to identify the pinouts on a Hall sensor by measuring resistance between it's pins. However I cannot find it now when I search for it.

From what you've posted there is no possible way to look up the maker. Your best bet is to search for four pin hall effect sensor datasheets. Following the traces on the boards and you should be able to find out what the pin usage is.

The 4 pin ones are almost always an "analogue hall bridge" and will work in differential mode. There are just 4 elements in a bridge (diamond shape) that change "resistance" according to a north or south pole.

If you want to test it, use a 2k7 series resistor in series with any 2 pins, powered from a 5v supply or a 9v battery. Then when you put a N or S magnet pole neat it the voltage on those 2 pins will go up or down.