Normally Open (NO) Reed Switches.
A reed switch refers to an electric switch that operates when a magnetic field is applied to it. A simple reed switch contains a pair of ferromagnetic flexible metal contacts in a hermetically sealed glass envelope. In a normally open reed switch, the contacts are generally opened, and they close in the presence of a magnetic field. Conversely, in a normally closed reed switch, the contacts are generally closed, and they open as the magnetic field is applied. When the magnetic field is removed, the switch goes back to its original position. An electromagnetic coil, making a reed relay or a permanent magnet near the reed, may activate the switch. The metal component inside the reed switch envelope is referred to as a reed. Sometimes, the external wire lead and the internal components may be collectively known as a reed.
Both reed and hall effect switches are magnetic switches because their properties change in the presence of a magnetic field. Unlike reed switches, hall effect switches are transducers that convert magnetic energy to electrical energy. They become switches with some additional circuitry. Contrary to the reed switches, hall effect switches have no moving components, so they are not influenced by mechanical shocks. On the other hand, reed switches are real magnetic switches that change their state when the magnetic field is applied or removed. Unlike hall effect switches, these switches are not sensitive to the polarity of the magnetic field.
Normally open Reed Switch Specification:
Product category: Reed Switches
Configuration: Normally Open (NO)
Power rating: It varies from product to product and depends on the manufacturer. It is given in watts.
Current rating: It also varies from product to product and depends on the manufacturer. It is given in amperes (amps).
Normally open Reed Switch Applications:
Reed switches are used in environments where chemicals or explosive gases are present because any sparking reaction due to switching action is contained by a glass case and switch encasing. These switches are employed as speed sensors in treadmills, car gears, or bicycle wheels. Electronic devices, having a clamshell design like laptops and flip phones, contain reed switches that act as proximity sensors. Reed switches are also used in electric keyboards because the glass enclosure of the contacts protects them against dust, dirt, and other particles. The reed switches are used to control diving equipment like cameras or flashlights.
These switches are of good quality and work well. What I found is that if the magnet used is too strong, the switch gets over-energized and does not release for a while after removing the magnet so ensure the right strength of magnet is used. I glued the switches onto my sliding glass doors and then glued magnets to the door latch handles to monitor if the doors are locked - works very well.