The
neon indicator bulb is used as an
indicator on
mains voltage appliances. This means that
they indicate
that the
power is on. You might have seen
switches that
light up
when turned on, these
contain a
neon bulb.
As the
name suggests the
neon bulb contains neon gas, This
gas
starts to glow with an
orange light when the
voltage on the
electrodes rises
above a
certain value (usually between 100 V - 150 V). The
neon
bulb is used in
series with a
resistor to
limit the
current flow
through it. In such a circuit the
voltage over the bulb will be
relatively constant.
Due to this the neon bulb is some times used as a
voltage stabilizer.