In relay switches, the electrical stimuli activate the electromagnets to form or hinder existing circuits. This mechanism lets them act as amplifiers or switches for the circuit depending on the application in use.
The reed relay mechanism
A reed relay has a reed switch with a reed-like contact, on which an electromagnet is directly acted upon. Located in a glass envelope, this set-up brings the reeds together to make contact when energised with electromagnet. They are much more reliable and require lower power to run than most other kinds of relays and are thus useful in several circuits.
Things to reflect before purchase
Durability is the most significant factor in relays, as one would not want frequent circuit maintenance. Electroplated nickel-iron reed contacts are generally preferred to ensure maximum life. Reed relays are available in standard voltages catering to the equipment on which it is used. It is also crucial to use the relay of the right voltage range for maximum efficiency and durability.
Some unique features for enhanced performance
In the coil present in a reed relay, a diode is often required to subdue the counter electromotive (EMF) force when the current is eliminated. Particularly with semiconductor devices, the counter EMF may be able to wreck any driver transistor. Attaching a diode in the relay helps prevent this potential damage and dramatically enhances the coil's performance. A magnetic shield is preferred in relays with a mu-metal can on its exterior or mu-metal screen on the interior. Such a design primarily helps in decreasing the impact of magnetic contact between closely packed reeds. It also reduces the coil power required.