Magnetic reed switch (reed? Switch), also known as reed switch, is an electrical switch controlled by an external magnetic field. 1936, Walter elwood of Bell Telephone Laboratory (Walter? B? Ellwood) invented the reed switch and applied for the patent 1940 in the United States on June 27th, with the patent number of reed switch 2264746? .
The basic type is to seal two magnetic reeds in a glass tube. Although they overlap, there is a small gap between them. When an external magnetic field is applied, two magnetic reeds will contact and then conduct electricity. ? Once the magnet is pulled away, the reed switch will return to its original position.
Magnetic reed switch symbol:
The old standard (GB/T5094- 1985) is S or SQ, and the new standard (GB/T5094.2-2003) is B or (GB/T20939-2007)BG.
The working principle of magnetic reed switch is very simple. Two magnetized reeds (usually composed of iron and nickel) with overlapping ends are sealed in a glass tube, and there is a small gap (only a few microns) between the two reeds. The contacts on the two reeds are plated with hard metals, usually rhodium and ruthenium, which greatly improves the switching time and product life. The glass tube is filled with high-purity inert gas (such as nitrogen). In order to improve its high-voltage performance, some reed switches will make the interior vacuum.
The reed acts as a magnetic flux conductor. When it is not operated, the two reeds are not in contact; When the magnetic field generated by the permanent magnet or electromagnetic coil passes through, the applied magnetic field generates different polarities near the end positions of the two reeds. When the magnetic force exceeds the elastic force of the reed itself, the two reeds will attract each other and make the circuit conductive; When the magnetic field weakens or disappears, the dry reed is released due to its own elasticity, and the contact surface will be separated, which will break the circuit.
Basically fully sealed form? Form? Answer? (? Always open? )? Basic structure and components of reed switch.
The picture above describes the form? Answer? (always open? (n.o.) or single-pole single-throw? (SPST)？ Reed switch? Form? b？ Represents a normally closed switch. c？ (SPDT) refers to a switch with reed, normally open blade and normally closed blade.
Form? c？ (single pole and double throw? ) Structure form of three reed magnetic reed switch? c？ (single pole and double throw? (SPDT)？ Basic structure of dry reed switch with three reeds.
Magnetic reed switch can make reed switch Xihe River, which is a permanent magnet and an external coil, instantly attract each other, which is incredible to think about. Its shortcomings are few, but the advantages of magnetic reed switch are numerous, for example, it is extremely small, light and fast, which is very suitable for high-frequency transmission applications! In this way, the magnetic reed switch is simply a unique product, which can be described as perfect.
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