Although they are both magnetic proximity sensors, Hall effect sensors & reed sensors are significantly different in the way they function. A Hall effect sensor is a three-wire, solid-state device whose output changes when exposed to a magnetic field. A reed sensor, on the other hand, is electrically a switch, with tiny contacts that open or close in the absence or presence of a magnetic field. In many applications either device could be used, but there are also some situations where one technology may be preferable over the other. A Hall effect sensor may be preferable to a reed sensor if you have the following requirements:
- Unlimited life. For example, if you are interested in sensing a spinning magnet that will operate a sensor billions of times, you should consider a Hall effect sensor.
Reed sensors generally have very long life compared to other electro-mechanical devices, but they cannot match the virtually infinite life of a Hall effect sensor.
I would add that Hall effect sensors are 3-terminal powered devices that usually require a 3V or 5V power supply and usually in the range of 10-20mA although some lower power Hall effect sensors have been released recently.
The reed switch being mechanical has only 2-terminals and requires no power to operate and so can be simpler to implement. Some newer reed switches are also rated for billions of cycles.
Electronic Products did a great round up of magnetic speed sensors:
I think these two sensors that is the hall effect sensors and the reed sensors are widely used in all cases as they have multi specifications in them. Reed sensors have a very long life when compared with the others.
<a href="http://www.windowsxphelpnow.com" rel="follow">windowsxphelpnow.com</a>