Reed Sensors
(191)Reed switches – useful in automation and everyday applications
Reed switches (also known as magnetically operated switches) have been widely used since the 1930s and their design has been continuously improved over the years. Thanks to their ease of use and simplicity reed switches are still used as door and window sensors to this day. The development of automation saw reed switches used in testing and drive systems. TME’s offer includes a wide selection of reed switches that can be used in household applications or included in drive installations.
What is a reed switch and how does it work?
A reed switch is made of a number of components including two contacts made from a ferromagnetic material that are sealed inside an air-tight glass envelope. It also has cables for placing the switch in electrical circuits such as alarm installations and specialised automatic systems. An outside magnetic field makes the contacts induce their own magnetic field, attract and snap together. Contacts are usually coated in metal such as gold, ruthenium or tungsten. Once a device is connected to an electric circuit, the reed switch contacts snap together creating a complete circuit and enabling the flow of electrical current.
But the reed switch itself is not enough. To ensure proper operation of the entire circuit, you need an actuator – this can be a permanent magnet or other component that generates a magnetic field. You can combine an electromagnetic coil with a reed switch to create a reed relay. Reed relays are used in e.g. automatic testing devices.
These circuits operate based on the position of the reed switch and actuator. If the reed switch is inside a magnetic field, the circuit starts working (the contacts snap together or open).
There are two types of actuators that differ in the magnet installation method, but both types work based on the same principle and are encased in airtight, waterproof envelopes that are also resistant to mechanical damage.
Surface actuators
Reed switches with surface actuators are suitable for installation on windows and doors: the magnet is installed on the moving part of a window and the reed switch is placed on its static part. It’s important to install both the reed switch and the magnet in a place where they won’t be influenced by a strong magnetic field – that would interfere with the whole alarm installation.
Reed switch components can be attached with double-sided tape that is now commonly placed on those small devices, but using screws is much more sustainable. One of the manufacturers of such reed switches is Omron, whose products are available at TME. Their default colour is white, but many households and apartments have door frames in other colours. That’s why, for large orders, reed switch components can be delivered in different colours at the customer’s request.
Flush-mounted actuators
The magnets included in these reed switches are installed inside window frames. They have the shape of connections which is a much more elegant solution. More and more door and window manufacturers are selling their products with pre-installed reed switches. TME offers discounts for large orders as well as orders for products not included in our regular catalogue.
Glass reed switches for special applications
Reed switches are also used in automation and circuits of various machinery. They enable precise positioning of pistons in motors used on assembly lines. These components are also useful for detecting the position of industrial robot arms found in car assembly plants.
Reed switches in glass envelopes from MEDER available at TME are also mounted on printed circuit boards to extend their capabilities.
High quality reed switches available at TME
Reed switches are widely used in everyday items, specialised devices, and electric systems. TME is a full-range supplier that offers a wide selection of reed switches from known and trusted brands.
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