Magnetic Switches: Magnetic switches have two overlapping flat contacts  which are sealed into a glass tube filled with inert gas. When approached by a permanent magnet the contact ends attract each other and make contact. When the magnet is removed, the contacts separate immediately. SPDT versions are also available. Reed switches have an expected life of more than 3 billion switching operations.  

Application 

Suitable for applications requiring a switched output for proximity,  linear limit detection, logging/counting, or actuation purposes. 
Temperature 
14^oF to 176^oF (-10^oC to +80^oC)  ;Special types -320^oF to +292^oF  (- 196^oC to +200^oC) 

Materials 
Brass, stainless steel, glass reinforced polyamide, aluminium, polyethylene. 

Output 
Switched output up to 1,000 cycle/second dependant on model. 

Configurations 
Rectangular or cylindrical section switch enclosures, threaded or bolted fixing to suit a wide variety of applications. 
Magnetic switches also available in slotted form for operation by a moving sheet iron vane. 
 

Operating Principle 
Pairs of north and south pole permanent magnets attached to a shaft (or other moving or rotating device) are arranged so that they pass close to a magnetic switch forming part of a capacitive circuit. 
Provided that the pulses generated in the circuit by the movement of the magnets maintain a capacitive charge in the circuit, the monitor signals that movement is taking place. Alternatively, an inductive proximity initiator can be used to detect the movement of ferrous and non-ferrous gear teeth and generate pulses in much the same way as a magnetic switch. A deactivation time delay relay ensures that both standstill or very slow movement are detected. For maximum speed monitoring an induction coil can be used as a pulse generator to detect passing magnets and generate a output current proportional to the speed of movement of the magnets. With a suitable arrangement of magnets on a rotating device, magnetic switches can be used to detect direction of rotation. 

Application 
Suitable for detecting continuity of movement or speed of movement in a wide range of rotating, linear actuating and other machinery. 

Temperature 
-100^oF to +150^oF  (-20^oC to 80^oC) 

Materials 
Brass, stainless steel, glass reinforced polyamide, aluminium, polyethylene. 

Output 
Switched or continuous analogue output. via suitable controllers. Capable of rotational speed detection in the range 200 - 3,000 rpm. 

Configurations 
Rectangular or cylindrical section switch or pulse generator enclosures with threaded or bolted fixing to suit a wide range of applications.