Electrical Engineering Stack Exchange
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Questions tagged [reed-switch]

An electromechanical switch controlled by a magnetic field applied to it. The metal contacts are flexible and somewhat resemble parts of reed plants, hence the name. A magnetic field causes the contacts to flex to either make contact with each other or produce a small air gap between them. Use for questions about reed switches, and in conjunction with the "switches" tag. Also consider using in conjunction with the "relay" tag, if applicable.

An electromechanical switch controlled by a magnetic field applied to it. The metal contacts are flexible and somewhat resemble parts of reed plants, hence the name. A magnetic field causes the contacts to flex to either make contact with each other or produce a small air gap between them.

Use for questions about reed switches, and in conjunction with . Also consider using in conjunction with , if applicable.

See Wikipedia's article on reed switches for more information.

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Why are some generic door alarm magnetic switches built using Normally Open reed switches instead of NC type?

Some generic, low-cost "door alarm" magnetic switch components are made of using "Normally Open (N/O)" type reed switches, ie, when the magnet is in proximity, the current stops flowing. If I were building such a system, I think I would choose a…
Phil
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Reed switch sticks until tapped

Why is the reed switch sticking when the magnet is no longer nearby? Only when I tap the switch it releases, otherwise it just sticks for many minutes. Are there any best practices (do's or don'ts) with reed switches? Does it matter what magnet…
jippie
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Why is this reed switch / solenoid circuit not working?

The (normally open) reed switch should close by waving a magnet across it, completing the circuit. The 6v solenoid lock should pull inwards allowing the door to be opened. When the magnet is removed the reed switch should open. So my issue is the…
Dominic Edwards
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How to prevent sealed in product battery drain on store shelf?

How can a microcontroller-based device prevent battery drain while the product is on the store shelf? We are creating a waterproof, sealed in product without any buttons. This means the battery is attached to the PCB in production and can't be…
Jason Schot
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How do I prolong the reed switch output time

I put a reed switch ( https://en.wikipedia.org/wiki/Reed_switch ) on the handle of a measuring wheel (perambulator). The reed switch will be activated up to around 20 times per second (every 50 ms). The sampling rate on my data acquisition is 200 Hz…
phell
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How to find a way to detect if a device was open or not

I'm making a device which is inside in an enclosure and at this point of the project it's relevant to understand if the enclosure/box was open. I was trying to understand if I can try to figure it out with a magnet and a ReedSwitch but if someone…
scuba
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Reed relay driving solenoid "sticks"

I have a transistor, driving a normally open reed relay (protecting transistor with flyback diode), driving a solenoid. The solenoid is actuating at about 3 Hz. The relay is good for a few million actuations. And then, it mysteriously stops…
ajs410
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Placing a reed switch behind a metal plate

If put a reed switch behind a metal plate in plastic casing and have the bar magnet sweep across the plate in parallel, would the reed switch activate? I would try it myself but the reed switches that I ordered from amazon are not here yet. But…
Zuzlx
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Reed switch only triggers with scope probe connected

I've run into a very odd problem. I've created the attached circuit, designed to cut power supply when a magnet is brought near the device. It works perfectly with the reed switch disconnected from the circuit. However, when everything is powered…
Alex
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Timer activated by reed switch on AC solenoid

I am trying to create a 2-digit timer that resets and then starts at the activation of an external AC solenoid, and pauses at the solenoid's deactivation. The circuit I have created (see schematic below) works fine with a neodymium magnet, but not…
MartinE
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How to turn on module like ESP8266 only when switch is activated?

I'm looking for a way that the ESP8266 (or alternative, like an Attiny85 with an RF module) is only turned on once a reed switch (or similar sensor) has been triggered. The problem is that the ESP8266 should have just enough time to power on and…
Kevin Van Ryckegem
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Magnetic reed switch current ratings

I wish to use some 12 V, 5 W xenon light bulbs under separate shelves of a cabinet. I'd like them to power-on using a magnetic reed switch attached to the cabinet door. The magnetic reed switch I have has a current rating of 0.5 A 20 V DC: 10 W…
BobH
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Need to close or open a circuit (and keep it that way) with magnet

I need to build a circuit that closes when it detects the passing of a magnetic card. It should open again when the card passes again. So I need a simple magnetic reed (like this one). And some kind of switch component that closes when it detects a…
Baksteendegeweldige
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Reed Switches - Good brand, stuck in the closed position problem

I'm doing a project with an Arduino pro mini 3.3v that uses internal pull-up to detect changes on a reed switch sensor. I'm buying the reed sensors from AliExpress, and most of the time they work OK without problems, but in some random cases they…
ernewston
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Reed switch melting closed in simple LED circuit -- What resistor to use?

Made a simple circuit with a reed switch, wall power source and LED strip (for a bathroom occupied sign). Worked as I’d hoped at first. But, after a while, THE REED SWITCH MELTS CLOSED--leaving the light stuck on. Im guessing I need a resistor? …
Bryant Smith
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