This is a small device called a reed switch. When the device is exposed to a magnetic field, the two ferrous materials inside the switch pull together and the switch closes. When the magnetic field is removed, the reeds separate and the switch opens. This makes for a great non-contact switch. This switch can carry up to 1.2A.
Dry reed pipe is short for dry reed pipe, there is a contact of passive electronic switch components, it has a simple structure, the advantages of small size is easy to control, its shell is commonly a sealed glass tube, tube is equipped with two elastic reeds iron panels, poured has called a rhodium metal inert gas.At ordinary times, two of the glass tube made of special materials reeds are separated.When magnetic material near the glass tube, under the action of magnetic field lines, two reed pipe is magnetized and attract each other contact, reed will suck together, make the circuit connected nodes receive.Magnetic disappeared, two reeds due to the elasticity of itself apart, the line is disconnected.Therefore, as a signal of the magnetic fields to control the circuit switching device, with a dry reed pipe can be used as a sensor, is used to count, spacing and so on, in the security system is mainly used in the production of door magnetic, magnetic window), but also widely used in all kinds of communication equipment.In practice, usually with a permanent magnet control this two pieces of metal on it or not, so also known as magnetron.