Magnetic reed switches are a type of passive electronic switching device that operates by the influence of a magnetic field. These switches consist of a pair of magnetic, flexible, metal reeds enclosed within a small glass tube-like envelope. The main function of a reed switch is to control the flow of electrical current—when a magnetic field comes close, the reeds draw together, completing the circuit and allowing current to pass through. Conversely, when the magnetic field is removed, the reeds separate, breaking the circuit and stopping the flow of electricity. This simple but highly effective mechanism makes reed switches reliable components in various applications where contact must be made or broken in response to the presence or absence of a magnetic field.
The primary uses of magnetic reed switches are found in security systems, such as door and window sensors in home alARM setups, automotive sensors, telecommunications, and in some medical devices where their characteristics—such as no power consumption in the off state, capability to switch high-voltage loads, and long operational life—make them highly desirable. They operate effectively in harsh environments and remain unaffected by dirt, water, and most chemicals, which adds to their versatility. Key manufacturers that specialize in the production of magnetic reed switches include Littelfuse, Littelfuse">HAMLIN, Standex-Meder Electronics, and Coto Technology.