What is at value for reed switch?
The AT value is measured by centering the Reed Switch in a standard coil, to which an increasing current is applied. At a certain current (Amps) the Reed Switch closes by means of the magnetic field generated by the coil. This is the Operate (or Pull In) value, calculated as Amps x number of coil turns = AT.
What is a reed switch circuit?
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 the resistance of a reed switch?
Depending on the wire diameter, reed switch lead wires have a resistance of about 30-60 mOhm/inch (1.2-2.4 mOhm/mm).
How sensitive are reed switches?
With a magnetic sensitivity of 2 to 4 Ampere Turns (AT), typical operating time of 0.2 ms, and a typical release time of 0.1 ms, the reed switch is well-suited for very demanding applications such as hearing aids, pill cams, flip or slide phones, and laptop computers.
How sensitive is a reed switch?
How do you use a reed switch?
The switching mechanism is comprised of two ferromagnetic blades, separated by only a few microns. When a magnet approaches these blades, the two blades pull toward one another. Once touching, the blades close the normally open (NO) contacts, allowing electricity to flow.
How do I choose a reed switch?
Reed switches are magnetically actuated switches….Important electrical switch specifications to consider when searching for reed switches include:
- Current rating.
- AC voltage rating.
- DC voltage rating.
- Power rating.
How fast can a reed switch operate?
One generally sees one or two bounces occurring over a 50 ms to 100 ms period. Most small Reed Switches operate, including bounce, in the range of 100 ms to 500 ms.
Do reed switches need power?
In contrast, reed switches are passive components that do not require any power to operate.
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.
What is the working principle of reed switch?
Normally Closed Reed Switches Normally Closed reed switches operate on the same principle, except that the switch uses a built-in magnet to keep its two contacts in a polarized state. This means that the switch’s default position is to keep the circuit closed, allowing the electrical current to flow continuously.
What is the contact rating of a reed switch?
Reed switches are available in a variety of sizes as denoted by their contact ratings. Contact ratings can range from 3 VA to as high as 100 VA to accommodate a diverse array of switched load sizes. Reed switches use much less power than other electronic switch alternatives.
How much voltage can a reed switch handle?
Reed switches are normally rated to handle a maximum amount of current and voltage. But for electronic purposes, these most likely will never be exceeded, since reed switches normally can handle over 1 ampere of current and hundreds of volts, so this, again, is really no concern for electronics.
How can I reduce the inrush current of a reed switch?
The reed switch contact can be protected with a series resistor calculated to reduce the surge. Alternatively, the filament can be kept warm by means of a bias current, again avoiding the high Inrush current.