RFReed Switch Specifications and Manufacturers
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magnetic switch
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This page covers the basics of reed switches, including their technical specifications, and provides a list of reed switch manufacturers or vendors.
Reed switch specifications include pull-in, drop-out, maximum switching voltage, maximum switching current, and maximum switching power.
What is a Reed Switch?
- A reed switch is a magnetically activated mechanical switch.
- It consists of two metallic contacts enclosed in a small enclosure, usually a glass capsule.
- The contacts are magnetic and move in response to a magnetic field. A permanent magnet is needed to activate the switch.
- There are two main types of reed switches: SPST (Single Pole Single Throw) and SPDT (Single Pole Double Throw). The most common type is SPST, which can be either normally open or normally closed.
Figure 1: Reed switch construction and its symbol.
Reed switches are available in the following configurations:
- Normally open
- Normally closed
- Bistable
Reed Switch Specifications
The following specifications are important to consider when selecting a reed switch:
- Pull-in: The minimum magnetic field strength required to activate the switch, often measured in ampere-turns. In other words, it’s the magnetic field strength at which the reed switch is activated.
- Drop-out: The maximum magnetic field strength at which the contacts of the switch relax. In other words, it’s the magnetic field strength at which the reed switch is de-activated. This is also measured in ampere-turns. The pull-in value will always be higher than the drop-out value.
- Maximum Switching Voltage: The maximum voltage at which the contacts can be switched. This is a reference voltage used to determine contact switching performance.
- Maximum Switching Current: The maximum current at which the contacts can be switched. This is another reference used to determine contact switching performance.
- Maximum Carry Current: The maximum current that can flow continuously through the closed contact.
- Maximum Switching Power: A reed switch can be used with alternating current. Hence, its switching capability may be expressed in watts (W) or volt-amperes (VA).
Reed Switch Manufacturers
The following table lists popular reed switch manufacturers or vendors:
| Reed switch Manufacturers | Description |
|---|---|
| HSI Sensing, 3100 NORGE ROAD, CHICKASHA, OK 73018, USA | This company manufactures reed switches for various applications across different industries. They offer reed switches of different types: form A (SPST, normally open), form B (SPST, normally closed), and form C (SPDT, single pole double throw, break before make). |
| Littelfuse Inc. Chicago, IL, 60631 USA | This company offers a wide range of magnetically operated reed switches. They are available in bare glass and overmolded packages with a variety of specifications (mechanical, electrical, magnetic). |
| Reed Relays and Electronics India Limited, Anekal-Gumlapuram Road, Thally 635118, India | This company manufactures reed switches for various applications with round glass tubes and wire to achieve maximum seal strength. |
| Standex Electronics, Inc. | This company offers magnetic reed switches designed to address various specific applications, including high-frequency reed switches, high-voltage reed switches, high-power reed switches, SMD reed switches, and more. |
| STG Germany | This company offers reed switches with glass tubes ranging from 7 to 50 mm in length. The switches are available for switching capacities up to 120 W/VA, switching voltages from 0 to 10KV AC/DC, and switching currents from 0 to 3 A AC/DC. |
| Comus International, NJ, USA | Comus International manufactures reed switches of different types. |
