Dry reed switch is the abbreviation of dry reed switch, is a contact passive electronic switching components, with a simple structure, small size to facilitate control and other advantages, its shell is generally a sealed glass tube, the tube is equipped with two iron elastic reed electrical plate, but also filled with an inert gas called metal rhodium. Normally, the two reeds made of special materials in the glass tube are separated. When there is a magnetic material close to the glass tube, in the magnetic field under the action of magnetic lines of force, the two reeds in the tube are magnetized and attracted to contact each other, the reeds will be sucked together, so that the node connected to the circuit connected. After the external magnetic force disappears, the two reeds separate due to their own elasticity and the line is disconnected. Therefore, as a circuit switching device controlled by magnetic field signals, the reed switch can be used as a sensor for counting, limiting and so on (mainly used in security systems for the production of door and window magnets), and is also widely used in various communication devices. In practice, permanent magnets are usually used to control whether the two metal pieces are connected or not, so it is also known as "magnetron".
Normally open type: The state is off, and the magnet is on when it is close to give a signal. On the contrary, the magnet leaves to break the signal.
Normally closed type: The state is closed, and the magnet is close to the open signal. On the contrary, the magnet leaves the conduction signal. 

Features and applications.
1,Dry type reed switch is compact and small in weight and can be installed in extremely limited space, which is extremely suitable for miniaturized equipment.
2,Dry reed switch components are hermetically sealed in an inert gas atmosphere and never come into contact with the outside environment, resulting in a long working life.
3,Dry reed switches do not use sliding elements, so there is no metal fatigue associated with all metal degradation, ensuring virtually unlimited mechanical life.
4,Reed switches are well used in cell phones, program-controlled switches, copiers, washing machines, refrigerators, cameras, disinfection cabinets, door magnets, window magnets, electromagnetic relays, electronic scales, liquid level meters, gas meters, water meters and so on. 

Reed switch use precautions.
1,When cutting or bending the lead pin of the reed switch, extreme care must be taken to avoid applying undue stress and damaging the glass-to-metal seal. Proper clamping tools are required.
2, Encountering temperatures and excessive exposure times may cause damage to the glass-to-metal seal (cracking, leakage, etc.), so a fast and reliable soldering technique (process) must be used. The recommended welding conditions are 280 to 300°C for hand welding and 250 to 300°C for wave welding.