You probably have a couple of smoke detectors in your
house. In this edition of How Stuff
Works we will take one apart and see what's inside!
See also the
article on smoke detectors to understand how smoke
detectors work. Here is the smoke detector we will be
exploring today:
When you take off the cover you find that a smoke detector
is pretty simple. This one consists of a printed circuit board
(see the article Inside a
Remote Control for an explanation of printed circuit
boards), an ionization chamber (the silver cylinder
toward the top right in the following picture) and an
electronic horn (the brass cylinder toward the bottom
right in the following picture):
Here is a close-up of the board:
and the underside of the board:
Ionization chamber
The ionization chamber is an aluminum can containing the ionization
source. You can see that the can has slots in it to allow
air flow. The can itself acts as the negative plate of the ionization
chamber.
Underneath the can is a ceramic holder that contains the
positive plate of the ionization chamber. Under that plate is
the ionization
source, WHICH YOU WANT TO BE SURE TO NOT DISTURB.