Re: How does a buzzer work?

There are many kinds of buzzers and they work in different ways.  Let me 
give you a few examples:

1)  One kind of buzzer uses a coil of wire.  When you press a switch (1), 
the coil has an electical current flow through it.  This causes the coil to 
create a magnetic field.   The magnetic field pulls a piece of metal 
(ferrous metal like steel) toward it, the metal strikes another piece of 
metal creating a sound.  At the same time, the movement of the metal causes 
a second switch (2) to open.  The electrical current is interrupted.  The 
metal piece returns to a rest position.  As long as the first switch (1) is 
closed, the cycle repeats and the sound of the metal sriking metal causes 
the buzz.

2)  Another kind of buzzer uses a transistor circuit to supply a varying 
voltage to a piezo-electric disk.  The disk flexes when voltage is applied 
to it.  The disk flexes back and forth due to the varying voltage applied to 
it.  This creates a sound.

There are many other approaches to creating a buzzer.

Gus Calabrese