In this tutorial we will use one magnetic – contact door sw / sensor and a buzzer for making a “noise” when a door is opened. Normally the reed is ‘open’ (no connection between the two wires). The other half is a magnet. When the magnet is less than 13mm (0.5″) away, the reed switch closes.


TV, laptops, phones, printers, alarms, cars, toys… they all have one common thing. They all need to be turned on and off, and so they all have at least one switch on them. Switches are the most simple and direct form of user input for any kind of device. They let the user give a clear instruction to a device, so the device in turn can respond appropriately. There are several types of switches, in different forms and sizes, and in this tutorial we will examine the most common among them.