User Manual

61
Lesson 11 Reed Switch
Introduction
A reed switch (as shown below) is used to detect the magnetic field. Hall sensors are
generally used to measure the speed of intelligent vehicles and count in assembly lines, while
reed switches are often used to detect the existence of a magnetic field.
Components
- 1 * Raspberry Pi
- 1 * Breadboard
- 4 * Jumper wires (Male to Male, 2 red and 2 black)
- 1 * Network cable (or USB wireless network adapter)
- 1 * Reed switch module
- 1 * Dual-color LED module
- 2 * 3-Pin anti-reverse cable
- 1 * Magnet (Self provided)
Experimental Principle
A reed switch is a type of line switch component that realizes control by magnetic signals. It
induces by a magnet. The “switch" here means dry reed pipe, which is a kind of contact
passive electronic switch component with the advantage of simple structure, small size, and
convenient control. The shell of a reed switch is commonly a sealed glass pipe in which two
iron elastic reed electroplates are equipped and inert gases are filled. Normally, the two
reeds made of special materials in the glass tube are separated. However, when a magnetic
substance approaches the glass tube, the two reeds in the glass tube are magnetized to
attract each other and contact under the function of magnetic field lines. As a result, the
two reeds will pull together to connect the circuit connected with the nodes.
After external magnetic force disappears, the two reeds will be separated with each other
because they have the same magnetism, so the circuit is also disconnected. Therefore, as a
line switch component controlling by magnetic signals, the dry reed pipe can be used as a
sensor to count, limit positions and so on. At the same time, it is widely used in a variety of
communication devices.