52mm Reed Switch NO/NC 3‑Pin (SPDT) 🧲

The 52mm Reed Switch NO NC 3 Pin is a glass‑encapsulated, magnetically actuated switch designed for low-voltage, low-current signal switching. Inside the hermetically sealed glass tube are two ferromagnetic reeds that open or close in response to an external magnetic field. This 3‑pin configuration provides SPDT changeover functionality, offering both Normally Open (NO) and Normally Closed (NC) contacts with a common terminal. Ideal for Arduino, Raspberry Pi, and other microcontroller projects, as well as industrial sensing, this component delivers reliable, contactless actuation in a compact format.

Key Features ✨

• Magnetic actuation: Contacts close or open under an external magnetic field; removes the need for mechanical buttons in many sensing applications.
• SPDT changeover (NO/NC): 3‑pin design provides Common (COM), NO, and NC terminals for flexible logic integration.
• Hermetically sealed glass capsule: Protects contacts from dust, moisture, and contaminants for higher reliability.
• Compact and lightweight: Easy to integrate into electronics modules, enclosures, and sensor assemblies.
• Low power: Passive “dry contact” switch draws virtually no current, ideal for battery‑powered electronics components.

Technical Specifications 📐

• Voltage Range: 3.3V ~ 60VDC
• Load Current Max.: 2A
• Switching Current: 1A
• Max Contact Rating: 60W
• Mechanical & Electrical Lifecycle: ≈ 100,000 cycles
• Contact Resistance: 100 mΩ
• Insulation Resistance: 1E9
• Operating Temperature Range: -50 to 140°C
• Length: 28 mm
• Approx. Weight: 5 g

Pinout and Wiring 🔌

• COM (Common): Shared terminal that toggles connection between NO and NC.
• NO (Normally Open): Open at rest; closes to COM when a magnet is present.
• NC (Normally Closed): Closed to COM at rest; opens when a magnet is present.

Use a pull‑up or pull‑down resistor (internal or external) when interfacing with a microcontroller GPIO to obtain a stable logic level. For Raspberry Pi (3.3V logic) and Arduino (5V logic), the switch functions as a simple dry contact to ground or VCC.

Applications 🚪🚴‍♂️🏭

• Sensor systems: Door/window sensors, bicycle speedometers, magnet presence detection.
• Electronic devices: Keyboards, appliances, medical devices, and DIY sensor modules.
• Automotive: Position detection for doors, seat belts, and movable components.
• Industrial automation: Position and motion sensing in machinery and equipment.

Advantages ✅

• Electrical isolation: Hermetic glass envelope improves reliability in harsh environments.
• Low power consumption: No coil or continuous drive current required.
• Long lifespan: Minimal wear due to non-contact actuation.
• Fast response: Millisecond‑level switching for responsive sensing.

Limitations ⚠️

• Magnetic interference: Nearby magnetic fields can cause false triggers—ensure proper placement and shielding if needed.
• Fragility: Glass capsule can break under impact; handle and mount with care.
• Current capacity: Not suitable for high‑current loads beyond the stated ratings; protect contacts when switching inductive loads.

Example Connection with Arduino 💡

Simple circuit to turn on the onboard LED when the reed switch closes (using the internal pull‑up for reliable logic):

 // Arduino example: Reed switch to LED const int reedPin = 2;   // Reed switch connected between pin 2 and GND const int ledPin  = 13;  // Onboard LEDvoid setup() {   pinMode(reedPin, INPUT_PULLUP); // Enable internal pull-up   pinMode(ledPin, OUTPUT); }void loop() {   bool closed = (digitalRead(reedPin) == LOW); // LOW when switch is closed to GND   digitalWrite(ledPin, closed ? HIGH : LOW); }  

• Wiring: Connect one reed terminal to GND and the other to D2. Enable INPUT_PULLUP as shown.
• Debounce: Reed switches can exhibit contact bounce; consider a small RC filter or software debouncing for critical timing.

Using with Raspberry Pi 🧠

• Connect one reed terminal to a GPIO pin and the other to GND.
• Enable an internal pull‑up in software or add an external ~10 kΩ pull‑up to 3.3V.
• Observe the 3.3V logic constraint—this is a dry contact, so it’s safe when wired as a passive switch to GND.

Best Practices 🔧

• Inductive loads: When switching relays, motors, or solenoids (within the 60W rating), use a flyback diode or snubber to protect contacts.
• Mounting: Support the glass body; avoid mechanical stress on the leads.
• Magnet placement: Sensitivity depends on magnet strength and approach angle/distance—test in final enclosure.

The 52mm Reed Switch NO NC 3 Pin is a versatile, reliable choice for Arduino, Raspberry Pi, and other microcontroller projects where simple, low‑power magnetic detection is required. With SPDT flexibility, robust sealing, and compact size, it’s an essential addition to your electronics components toolkit.