User Guide

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9 – Building a Smarter Doorbell
A doorbell is a push-button switch that closes a small electrical
circuit when a visitor presses the button. With the circuit closed,
electricity flows into components that make the chime or buzzing
sound.
With a Raspberry Pi, you can make a much smarter doorbell –
one which is capable of doing a lot more than playing a sound.
Anything that the Pi can do, you can do in response to someone
ringing the doorbell.
In this chapter, you will see how to make a prototype Raspberry
Pi-powered doorbell.
You need:
1. A Raspberry Pi running Raspbian.
2. A set of speakers. For more information about
suitable speakers, see section 9.2.
3. A door chime sound effect as an MP3.
4. A doorbell (“bell push”) or momentary push switch.
5. Some wire.
6. One 330 Ω resistor.
7. A solderless breadboard, perfboard, or stripboard
for attaching wires and components.
9.1 The Button Circuit
The push-button circuit used in this project is the same as you
can see described in section 7.5 Basic Input on page164.
The doorbell on the front of your house is usually wired into the
“mains” electrical supply. Do not connect the Pi doorbell to the
mains supply, and consult a qualified electrician before
attempting to remove your current doorbell.