Reed Switch | Normally Open Magnetic Contact | 4x28mm NO Sensor

This magnetic reed switch is a simple, non-contact switch for your electronics. The switch is sealed in a 4x28mm glass tube and turns on when a magnet is brought near. It’s a dependable way to sense position, closeness, or movement without touching anything. Features and Benefits - Normally Open (NO) contacts - The circuit is off by default and closes only when a magnet is there, making it good for triggers and alarms. - Glass-encapsulated design - This protects the internal contacts from dust and moisture, which gives the sensor a very long working life. - Compact 4mm x 28mm size - This small switch is tiny enough to fit into tight spaces for custom door sensors or hidden triggers. - Non-contact magnetic actuation - Since nothing touches, it provides millions of reliable switching cycles for your project. Applications - Home Security Systems: Make your own door or window sensor that triggers an alarm when opened. - Arduino and DIY Electronics: Use this with Arduino to count wheel rotations or sense when a lid is closed. - Level Sensing: Attach a magnet to a float in a tank to make a simple fluid level sensor. What It Is This is a Reed Switch, a type of proximity sensor designed for detecting the presence or absence of a magnetic field. It functions as a Normally Open (NO) magnetic contact, meaning the circuit is open (no current flows) until a magnetic field is detected, at which point the contacts close. The unit measures 4mm x 28mm and is constructed from glass. This product is supplied as a pack of 10 pieces, suitable for various electronics module applications. Key Uses & Applications Reed switches like this 4x28mm NO sensor are widely used in a variety of industrial sensor and general electronics applications. They are effective as native sensors for simple on/off detection tasks. Common uses include door and window alarms, where the switch detects the opening or closing of a door. They can also be integrated into security systems or used for position sensing in machinery. Their compact size makes them suitable for tight spaces where larger barrel sensor or optical sensor types might not fit. How to Choose When selecting a reed switch, consider the required contact type; this product is Normally Open. The physical dimensions, 4mm x 28mm, are crucial for fitting into your intended application. Evaluate the material, which for this switch is glass, for its suitability to the operating environment. For testing a proximity sensor like this, you would typically use a multimeter to check for continuity when a magnet is brought near the switch, confirming its Normally Open function.