When a reed switch is packaged into a different form or housing, it is then referred to as a Reed Sensor. A permanent magnet can be used to actuate the Reed Sensor contacts. Once the magnet is distanced from the switch, the contacts will reopen and remain open until the magnet is moved into position again. The example shown here is a simple perpendicular movement of the magnet in proximity to the reed switch. Since the magnetic field is three dimensional, it is important to note that there are many possible variations for the magnet’s position and movement as well as magnetic strength and switch sensitivity which will determine the actuation point or points.