can anybody tell me how hall effect sensor works?
i want to detect a direction.

 

A hall effect device measures the strength of a magnetic field, if you want to detect a direction a digital compass would probably be a better bet.

 

if i use digital compass, this device must always stay horizontal.
but my project need something that can measure direction at any condition.
my project is for indoor application. i mean, in a building. :wink:

 

Does this mean you want to measure direction in 3-dimensional space (azimuth and elevation) as opposed to just azimuth, or are you wanting a compass that will determine azimuth regardless of its orientation?

 

Perhaps you ought to post exactly what you are trying to do?, a hall effect sensor is normally used for detecting a moving magnet - often on a rotating shaft or wheel. VCR's usually have a fair few inside, used as reel sensors (although some VCR's use IR sensors instead), and as sensors in the capstan and drum motors.

 

The most sensitive hall effect sensor I have found is made by Allegro, but their best is not good enuf to work with the earth's magnetic field. Even so, their website may give you some info on how they work. Most electonic compasses use some form of flux gate.

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