What does a reed switch look like?
The reed switch was born in 1936. It was the brainchild of W.B. Ellwood at Bell Telephone Laboratories, and it earned its patent in 1941. The switch looks like a small glass capsule with electrical leads poking out of each end.
What is a reed switch?
A reed switch is an electromagnetic switch used to control the flow of electricity in a circuit. They are made from two or more ferrous reeds encased within a small glass tube-like envelope, which become magnetised and move together or separate when a magnetic field is moved towards the switch.
What is a reed switch GCSE?
A normally open reed switch consists of a glas tube with two reeds sealed inside it. The reeds are connected to an external circuit. If there is no magnetic field present, the reeds are unmagnetized. There is a gap between the reeds, so the circuit is not complete and no current can flow.
Are all reed switches the same?
Reed switches come in two main varieties called normally open (normally switched off) and normally closed (normally switched on). The key to understanding how they work is to realize that they don’t just work as an electrical bridge but as a magnetic one as well: magnetism flows through them as well as electricity.
Why is it called a reed switch?
The “reed” is the metal part inside the reed switch envelope that is relatively thin and wide to make it flexible. It somewhat resembles part of some reed plants. The term “reed” may also include the external wire lead as well as the internal part.
How do you use a reed switch?
A reed switch like this is normally open (NO) (normally off), unless a magnet is positioned right next to it, when it switches on, allowing a current to flow through it. Take the magnet away and the contacts—made from fairly stiff and springy metal—push apart again and return back to their original positions.
Is a reed switch normally open or closed?
The Form A magnetic reed switch has two contacts which are Normally Open (NO). Having NO contacts means that the introduction of a magnetic field will cause these contacts to close. That closure, in turn, also closes the circuit, thereby conducting electricity.
Do reed switches have polarity?
Just as your magnet may have two poles, the reed switch’s pair of ferrous contacts are also polarized. The position, distance, and orientation of your magnet all play a role in determining how the switch activates.
Where are reed switches used?
Reed switches, Reed Sensors, and Magnet Sensors find applications in vast areas, from simple position sensing in doors, to more complicated ones used in the military, to more sophisticated cellular phone radio frequency (RF) switching electronics and in the medical industry.
What is reed switch/sensors?
What are Reed switch/sensors? Reed switch is also called an inductive-magnetic sensor, so it is grouped in special inductive sensors. Reed switch is printed in a bakelite box. If the switch enters a magnetic field, the contact feathers become closed, and the sensor provides electrical signals.
What is a ferromagnetic reed switch?
Reed switch. It consists of a pair of contacts on ferromagnetic metal reeds in a hermetically sealed glass envelope. The contacts may be normally open, closing when a magnetic field is present, or normally closed and opening when a magnetic field is applied. The switch may be actuated by a coil, making a reed relay,…
What is an inductive reed switch?
Reed switch is also called an inductive-magnetic sensor, so it is grouped in special inductive sensors. Reed switch is printed in a bakelite box. If the switch enters a magnetic field, the contact feathers become closed, and the sensor provides electrical signals.
How does an NC reed switch work?
An NC reed switch works the other way. The reeds are already in contact in their natural position, providing a closed circuit and allowing current to flow across the switch when no magnet is present. Introduction of a magnetic field with reversed polarity pushes the contacts apart, breaking the circuit.