They are illuminated by either a transformer or a switching power supply running at voltages ranging between 3000 and 15000 volts and between 30 and 120 mA. Neon signs are a type of Cold Cathode lighting.
The light-emitting tubes form colored lines with which a text can be written or a picture drawn, including various decorations, especially in advertising. By programming sequences of switching parts on and off there are many posibilities for dynamic light patterns.
See also: Timeline of lighting technology,
Neon,
1911 in science,
Neon lampApplications