Reed switch, also known as reed tube or reed switch, is a kind of magnetic sensitive special switch and the main component of reed relay and proximity switch. When using the reed switch in a sensitive environment, magnets are usually used to activate the reed switch. It is very important to know this interaction clearly to ensure the normal operation of the sensor. Sensors may be used in normally open mode, normally closed mode or hold mode.
 The advantages of glass are its small size and light weight, which makes them easy to install and inconspicuous. The operation of the switch is very small, thus eliminating the cumbersome cam or crank, so there will be no metal fatigue phenomenon related to all metal degradation, ensuring virtually unlimited mechanical service life. Moreover, it can be installed in an extremely limited space and is very suitable for miniaturized equipment. Magnetic reed switches and suitable magnets are cheap and easy to obtain.
 The switching components of the reed switch are hermetically sealed in an inert gas atmosphere and will never contact with the external environment, thus greatly reducing the contact oxidation and carbonization caused by contact sparks during the opening and closing process of the contact. And prevent external organic vapor and dust and other impurities from eroding the contacts. Long service life.
 The reed is thin and short, and has a high natural frequency, which improves the on-off speed of contacts, and its switching speed is 5~10 times faster than that of ordinary electromagnetic relays.
 The water level sensor of the automatic water level control device of humidifier is composed of reed switch, float ball, roller skating and permanent magnet. When the floating ball moves up and down due to the rise and fall of the liquid level, the permanent magnet will be driven to move up and down by pulleys and ropes; When the permanent magnet moves to the set position of the reed switch, the normally open contact in the reed switch is connected by the magnetic field of the permanent magnet; When the permanent magnet is removed, the contact is released. According to the connection and disconnection of reed switch contact, the water level signal can be known.
 This principle can be applied to humidifier, aromatherapy device, atomizer, etc.
 In addition to the applications in the above range, there are also the organ used by electric and electronic pedal keyboards. Electronic organ players often use magnetic spring switches and contact glass shells to protect them from dirt, dust and other particles. They may also be used to control diving equipment such as flashlights or cameras, which must be sealed to keep pressurized water.

 Reed switch is widely used. Besides the above products, there are toys, sensors, float switches, battery control panels, electronic locks, security monitoring, access control, cordless vacuum cleaners and sweeping robots, and it can also be used for computer cooling fans and disk drives.