About Reed Sensors

About Reed Sensors
Reed sensors use a magnet or electromagnet to create a magnetic field that opens or closes a reed switch within the sensor. This deceptively simple device reliably controls circuits in a wide range of industrial and commercial goods.

In this article, we’ll discuss how reed sensors operate, the different types available, the differences between Hall Effect Sensors and reed sensors, and the key benefits of reed sensors. We’ll also provide an overview of industries that use reed sensors and how MagneLink can help you create custom reed switches for your next manufacturing project.

How Do Reed Sensors Work?
A reed switch is a pair of electrical contacts that create a closed circuit when they touch and an open circuit when separated. Reed switches form the basis for a reed sensor. Reed sensors have a switch and a magnet that power the opening and closing of the contacts. This system is contained within a hermetically sealed container.

There are three types of reed sensors: normally open reed sensors, normally closed reed sensors, and latching reed sensors. All three types may use either a traditional magnet or an electromagnet, and each relies upon slightly different methods of actuation.

Normally Open Reed Sensors
As the name implies, these reed sensors are in the open (disconnected) position by default. When the magnet in the sensor reaches the reed switch, it turns each of the connections into oppositely charged poles. That new attraction between the two connections forces them together to close the circuit. Devices with normally open reed sensors spend most of their time powered off unless the magnet is purposefully active.

Normally Closed Reed Sensors
Conversely, normally closed reed sensors create closed circuits as their default position. It isn’t until the magnet triggers a specific attraction that the reed switch disconnects and breaks the circuit connection. Electricity flows through a normally closed reed sensor until the magnet forces the two reed switch connectors to share the same magnetic polarity, which forces the two components apart.

Latching Reed Sensors
This reed sensor type includes the functionality of both normally closed and normally open reed sensors. Rather than defaulting to a powered or unpowered state, latching reed sensors stay in their last position until a change is forced upon it. If the electromagnet forces the switch into an open position, the switch will stay open until the electromagnet powers up and makes the circuit close, and vice versa. The operate and release points of the switch create natural hysteresis, which latches the reed in place.