What is a Magnetic Reed Switch and How does it Work?
What is a Magnetic Reed Switch?
A magnetic reed switch is an electromechanical device that operates by the presence or absence of a magnetic field. It consists of two ferromagnetic metal contacts, known as reeds, which are hermetically sealed within a glass envelope. The design allows these components to function reliably in various environments without exposure to contaminants. The reeds are typically made from an alloy of nickel and iron, which makes them responsive to magnetic forces.
In its most common configuration, the reed switch is normally open, meaning that the contacts are separated when no magnetic field is present. When a magnet approaches the switch, it induces magnetization in the reeds, causing them to attract each other and close the circuit. Conversely, when the magnetic field is removed, the reeds return to their original position due to their inherent springiness, thus opening the circuit again.
What is a Magnetic Reed Switch and How does it Work
How Does a Magnetic Reed Switch Work?
The operation of a magnetic reed switch can be broken down into several key steps:
Magnet Proximity: When a permanent magnet or an electromagnetic coil comes close to the reed switch, it generates a magnetic field that interacts with the ferromagnetic reeds inside.
Magnetization of Reeds: As the magnetic field reaches sufficient strength, it magnetizes the reeds. This process causes them to become attracted to each other due to their ferromagnetic properties.
Closing of Contacts: Once magnetized sufficiently by the external magnetic field, the reeds move together and make contact with each other. This action completes an electrical circuit allowing current to flow through.
Circuit Opening: When the external magnetic field is removed (i.e., when the magnet is taken away), any residual magnetism on the reeds dissipates quickly due to their design and processing (they are often annealed to prevent unwanted retention). The springs in the reeds pull them apart again, breaking the circuit.
Types of Reed Switches: There are different configurations for reed switches:
Normally Open (NO): The default state has contacts apart; they close when exposed to a magnetic field.
Normally Closed (NC): The default state has contacts touching; they open when exposed to a magnetic field.
Changeover Switches: These have three terminals and can connect one terminal while disconnecting another based on magnetic influence.
Reed switches are widely used in various applications such as security systems (e.g., door/window sensors), automotive systems (e.g., position sensing), and consumer electronics due to their reliability and simplicity.
This sensor can detect the heart’s and brain’s electromagnetic fields, which are undetectable to other sensor technologies.
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