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3.2 Feel the Magnetism¶

The most common type of reed switch contains a pair of magnetizable, flexible, metal reeds whose end portions are separated by a small gap when the switch is open.

A magnetic field from an electromagnet or a permanent magnet will cause the reeds to attract each other, thus completing an electrical circuit. The spring force of the reeds causes them to separate, and open the circuit, when the magnetic field ceases.

A common example of a reed switch application is to detect the opening of a door or windows, for a security alarm.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

3 in 1 Starter Kit

380+

3 in 1 Starter Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

SunFounder R3 Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

Reed Switch

-

Schematic

../_images/circuit_3.2_reed.png

By default, pin 2 is low; and will go high when the magnet is near the reed switch.

The purpose of the 10K resistor is to keep the pin 2 at a steady low level when no magnet is near.

Wiring

../_images/feel_the_magnetism_bb.jpg

Code

Note

  • You can open the file 3.2.feel_the_magnetism.ino under the path of 3in1-kit\basic_project\3.2.feel_the_magnetism.

  • Or copy this code into Arduino IDE.

  • Or upload the code through the Arduino Web Editor.

After the code is uploaded successfully, when a magnet is near the reed switch, the serial monitor will print 1.