Reed switch(short for sealed magnetic contact) - an electromechanical device, which is a pair of ferromagnetic contacts sealed in a sealed glass flask. When a permanent magnet is brought to the reed switch or an electromagnet is turned on, the contacts close. Reed switches are used as proximity switches, proximity sensors, etc.
A reed switch with an electromagnetic coil makes up a reed switch relay.
There are also reed switches that open the circuit when magnetic field and there are reed switches with a switching group of contacts.
Reed switches also differ in design features. They are dry (with dry contacts) and mercury, in which a drop of mercury wets the contacting surfaces, reducing their electrical resistance and preventing vibration of the plates during operation.
Options
Magnetomotive force of actuation- the value of the magnetic field strength at which the reed switch contacts close.
Release magnetomotive force- the value of the magnetic field strength at which the reed switch contacts open.
Insulation resistance- electrical resistance of the gap between the cores (in the open state).
Contact transition resistance- resistance of the contact area, which is formed when the cores are closed.
Breakdown voltage- voltage at which breakdown of the reed switch occurs.
Response time- time between the moment of application of the control magnetic field and the moment of the last physical closure of the electrical circuit by the reed switch.
Release time- time between the moment of removal of the magnetic field applied to the reed switch and the moment of the last physical opening of the electrical circuit by the reed switch.
Capacity- electrical capacitance between the reed switch terminals in the open state.
Maximum number of operations- the number of operations at which all the main parameters of the reed switch remain within acceptable limits.
Maximum power - maximum power, switched by a reed switch.
Switching voltage
Switching current
Advantages
- The reed switch contacts are in a vacuum or in an inert gas and do not burn, even if a spark occurs between the contacts when closing or opening.
- Durability of reed switches. It is believed that if you do not hit the reed switch and do not miss very high currents, then the service life of the reed switch is infinite (although the technical data for reed switches indicates limitations, 108 - 109 or more operations).
- There is practically no rattling when turning on and off, there is no “uncertainty of pressing”. A reed switch can have only two clear states - on and off.
- Smaller size compared to a classic relay designed for the same current.
- There is no need to use refractory and precious metals for contacts.
- Reed switches are almost silent.
- High performance.
Flaws
- Expensive and heavier compared to open contacts.
- The need to create a magnetic field.
- Difficult to install.
- Fragility. Cannot be used in environments with strong vibrations and shock loads.
- Limited response speed
Application
- Keyboards - keyboard synthesizers and computers (virtually not used in computer keyboards since the mid-1990s) ( good use all the advantages of a reed switch).
- Keyboards for industrial devices where durability and explosion protection are required.
- Sensors: security, bicycle computers, etc.
- Underwater equipment: flashlights for diving, spearfishing.
- Elevators: cabin positioning sensors
- TV and radio equipment
The main trend is the replacement of reed switches with solid-state Hall sensors
Gerkomn (short for “sealed [magnetically controlled] contact”) is an electromechanical device consisting of a pair of ferromagnetic contacts sealed in a sealed glass flask. When a permanent magnet is brought to the reed switch or an electromagnet is turned on, the contacts close. Reed switches are used as position sensors, limit switches, etc.
A reed switch with an electromagnetic coil makes up a reed switch relay.
There are varieties of reed switches according to the contact group: with a closing contact, an opening contact and a switching contact.
Reed switch with a closing contact - the contact is open in the absence of a magnetic field, and closes in the presence of a magnetic field.
Reed switch with open contact - the contact is closed in the absence of a magnetic field, and opens in the presence of a magnetic field.
A reed switch with a switching contact has three terminals - in the absence of a magnetic field, one pair of terminals is closed, and in the presence of a magnetic field, the other pair of terminals is closed.
Reed switches also differ in design features. They are dry (with dry contacts) and mercury, in which a drop of mercury wets the contacting surfaces, reducing their electrical resistance and preventing vibration of the plates during operation.
Difference between a reed switch and a Hall sensor:
Reed switch is an element that mechanically closes (or opens) electrical circuit with proper change in magnetic field strength;
Hall sensor is a semiconductor device through which flows during operation. electric current and a transverse potential difference arises, proportional to the magnetic field strength.
The reed switch contacts are in a vacuum or in an inert gas and burn slightly, even if a spark occurs between the contacts when closing or opening.
Durability of reed switches. It is believed that if you do not hit the reed switch and do not allow very large currents to pass through, then the service life of the reed switch is infinite (although the technical data for reed switches indicates limitations, 10 3 --10 8 or more operations).
Smaller size compared to a classic relay designed for the same current.
There is no need to use refractory and precious metals for contacts.
Reed switches are almost silent.
High (relative to classic relays) performance.
Flaws
· The presence of chattering noise when turned on, which entails multiple operations in a short period of time.
· More weight compared to open contacts.
· The need to create a magnetic field.
· Susceptibility to external magnetic fields, need for protection from them
· Complexity of installation.
· Fragility - reed switches cannot be used in environments with strong vibrations and shock loads.
· Limited response speed.
Possibility of spontaneous opening of reed switch contacts at high currents
· Sometimes the contacts “stick” (remain in a closed state) - such a reed switch must be replaced.
Application.
· Keyboards - keyboard synthesizers and computers (virtually not used in computer keyboards since the mid-1990s) (successful use of all the advantages of the reed switch).
· Keyboards for industrial devices where durability and explosion protection are required.
· Sensors: security (door opening sensor), cycling computers, laptop top cover (opening and closing), etc.
· Underwater equipment: flashlights for diving, spearfishing.
Elevators: cabin positioning sensors
· Television and radio equipment
· Electronic meters current single-phase and three-phase (used in apartment buildings, in industry) [source not specified 508 days]
· The main trend is the replacement of reed switches with solid-state Hall sensors.
Special area of application - transmission devices discrete signals control and protection against current overloads of high-voltage electrical and radio engineering installations, such as high-power lasers, radars, radio transmitting devices, electrical installations and other types of equipment operating under voltages of 10 - 100 kV. Especially for these types of equipment, V.I. Gurevich developed reed relays with high-voltage insulation, the so-called “herkotrons” or “high-voltage insulating interfaces”, described in his books
Reed switch(short for sealed contact) - an electromechanical device, which is a pair of ferromagnetic contacts sealed in a sealed glass flask. When you apply a permanent magnet to the reed switch or turn on an electromagnet, the contacts close or open depending on the reed switch you select. Reed switches are used as proximity switches, proximity sensors, etc.
Advantages of using reed switches:
- Due to the fact that the closing and breaking conductors are located in a vacuum, they do not oxidize. When closing and opening, a spark does not jump between the conductors. These two features provide enormous durability to the reed switches. It is believed that if you do not hit the reed switch and do not allow very large currents to pass through, then the service life of the reed switch is infinite.
- There is no “noise” when turning on and off, no “uncertainty of pressing”. A reed switch can have only two clear states - on and off.
- High current. There is no need for clicking relays when you need to close or open circuits that carry high current.
Used in Soviet-made keyboards (from there you can pick up a huge number of them).
Nowadays they are used in intercoms to detect when the handset is picked up.
They can be used as relays, keys, sensors, etc., in general, a font is enough).
But be careful, it's a fragile item.
You might be interested
Reed switch(short for " ger metrical con
reed switch
Advantages
· Reed switches are almost silent.
Flaws
· Complexity of installation.
Application
· Television and radio equipment
Advantages and disadvantages of reed switch relays compared to small sealed relays.
Reed switch(short for " ger metrical con tact") is an electromechanical device consisting of a pair of ferromagnetic contacts sealed in a sealed glass flask. When a permanent magnet is brought to the reed switch or an electromagnet is turned on, the contacts close. Reed switches are used as proximity switches, proximity sensors, etc.
A reed switch with an electromagnetic coil makes up a reed switch relay.
There are also reed switches that open the circuit when a magnetic field occurs, and reed switches with a switching group of contacts.
Reed switches also differ in design features. They are dry (with dry contacts) and mercury, in which a drop of mercury wets the contacting surfaces, reducing their electrical resistance and preventing vibration of the plates during operation.
reed switch- this is an element that mechanically closes (or opens) an electrical circuit with a proper change in the magnetic field strength;
Advantages
· The reed switch contacts are in a vacuum or inert gas and burn slightly, even if a spark occurs between the contacts when closing or opening.
· Durability of reed switches. It is believed that if you do not hit the reed switch and do not allow very high currents to pass through, then the service life of the reed switch is infinite (although the technical data for reed switches indicates limitations, 10 8 -10 9 or more operations).
· Smaller size compared to a classic relay designed for the same current.
· No need to use refractory and precious metals for contacts.
· Reed switches are almost silent.
· High (relative to classic relays) performance.
Flaws
· The presence of chattering noise when turned on, which entails multiple operations in a short period of time.
· Expensive and heavier compared to open contacts.
· The need to create a magnetic field.
· Complexity of installation.
· Fragility - reed switches cannot be used in conditions of strong vibrations and shock loads.
· Limited response speed
· Sometimes the contacts “stick” (remain in a closed state) - such a reed switch must be replaced.
Application
· Keyboards for industrial devices where durability and explosion protection are required.
· Sensors: security (door opening sensor), bicycle computers, etc.
· Underwater equipment: flashlights for diving, spearfishing.
Elevators: cabin positioning sensors
· Television and radio equipment
Small-sized sealed relays
Specifications:
High vibration and shock resistance
Hermetically sealed housing.
