What is a Reed Relay?
It is basically a switching element created by the presence of 2 contacts in a tube containing gas in the reed relay. Reed relay was developed in 1936 by Bell Labs.
The elements with tiny contacts placed in the glass body are called reed relays. The position of iron-nickel alloy mini contacts in the enclosure made of aerated clear glass or other material in reed relays is replaced by permanent magnet or electromagnet.
In reed relays, the position of the contacts can be changed with a natural magnet or electromagnet. The pull and release time of the contacts of the reed relays used in the application is 0.5 milliseconds and the number of work is around 1-2 million. In some model reed relays, the section with the contacts is filled with 97% nitrogen and 3% hydrogen mixture gas in order to facilitate the flow of current.
In some models of security alarm systems, reed relays are used. For example, a reed relay (sometimes referred to as a reed sensor) and a magnet are placed on the entrance door, when the door is opened, the magnet changes its contact position as soon as the magnet moves away from the relay and the digital-based main circuit is warned.
Limit switches were used in the past to allow elevators installed in multi-storey houses to stand on the desired floor. However, since it operates more smoothly, the detection device consisting of an approach switch with reed relay and magnet has also started to be used. In this system, the reed relay element remains stationary, the magnet connected to the elevator car allows the contacts to change positions with the magnetic field.
Reed relay has many uses. For example, you can check whether a window or door is opened in this way. The advantage is; When using a physically controlled switch, malfunctions and physical contact failures are frequently encountered. The reed relay can also be used for a longer period of time as there is no contact.