12mm Reed Switch/Sensor

📌 Overview
A 12mm Reed Switch Sensor is a magnetic switch that detects the presence of a magnet and changes its state (ON/OFF).
👉 It is one of the simplest and most reliable contactless sensors used in electronics.
🧠 Working Principle
Inside the sensor → two thin metal reeds sealed in a glass tube
Normally → contacts are open (NO)
When a magnet comes near → reeds attract and touch → circuit closes
When magnet is removed → reeds separate again
✔ Works purely on magnetic field (no power needed for basic switch)
📊 Infographic Summary
┌──────────────────────────────┐
│ 🧲 12mm REED SWITCH SENSOR │
├──────────────────────────────┤
│ 🎯 Detects: Magnetic field │
│ ⚡ Voltage: Up to 24V │
│ 🔌 Output: Digital (ON/OFF) │
│ 📏 Size: 12mm (glass tube) │
│ 🧠 Type: Magnetic switch │
│ 🔁 Response: Instant │
└──────────────────────────────┘
🔌 Basic Connection
┌──────────────┐
│ Reed Switch │
├──────────────┤
│ Pin 1 → VCC / Signal
│ Pin 2 → GND
└──────────────┘
👉 Acts like a simple switch, so you can use it directly or with a pull-up resistor.
⚙️ Key Specifications
⚡ Max Voltage: ~24V DC
🔌 Max Current: ~1.2A
📏 Size: 12mm length (compact)
🌡 Temperature Range: -50°C to 140°C
🔁 Life Cycle: ~100,000 operations
📡 Output: Digital only (ON/OFF)
🌟 Key Features
🧲 Magnetic field detection
⚡ No power needed for basic operation
🔧 Very easy to use
💰 Extremely low cost
📦 Small and lightweight
🔒 Fully sealed (dust & moisture resistant)
🧪 Applications
🚪 Door/window security sensors
🚨 Burglar alarm systems
📦 Position detection (open/close)
🚲 Speed sensors (wheel rotation with magnet)
🤖 Robotics & automation
🧩 Smart home projects
🔗 Interfacing with Microcontrollers
Works with:
🔵 Arduino
📡 ESP32 / ESP8266
🍓 Raspberry Pi
👉 Use digital input pin to detect state change.
⚠️ Important Notes
⚠️ Fragile (glass body – handle carefully)
⚠️ Requires a magnet to operate
⚠️ Limited switching current (use relay for high loads)
⚠️ Sensitive to strong magnetic interference
💬 Real-world insight:
Reed switches are simple but can wear out if switching high current frequently (arcing effect).
🆚 Reed Switch vs Hall Effect Sensor
Feature
Reed Switch
Hall Sensor
Output
Digital (ON/OFF)
Analog/Digital
Power Required
No (passive)
Yes
Durability
Mechanical wear
No moving parts
Cost
Very cheap
Slightly higher
💡 Pro Tip
For better projects:
Use magnet + reed switch for door sensors
Add pull-up resistor (10kΩ) for stable readings
For high durability → consider Hall sensor instead