Page 252 - Electromechanical Devices and Components Illustrated Sourcebook

214 Electromechanical Devices & Components Illustrated Sourcebook

Neon Lights Neon Gas Glass Tube Electrode

The neon lighting cycle is created when a voltage is applied
across a pair of electrodes in a neon gas atmosphere. As elec-
trons flow from one electrode to the other, the gas becomes Terminal Wire
excited and produces visible light. Most of us have seen neon Figure 12-11 Neon Tube Lamp
lights used in advertising. The flashing open light at the end
of a long dark road is an icon of the American cinema.
Figure 12-9 shows the most common type of neon lamp.
These types of lamps are commonly used as night-lights and the bulb. When the lamp is turned on, it appears to have a
indicator lamps. It consists of a small glass bulb, which is purged flame and produces a subtle environment.
with neon gas, and two electrodes. When power is applied to the The glow, or plasma, of a neon lamp can extend over rather
electrodes, the lamp glows with a soft orange light. long distances, if the tube is properly constructed. Figure 12-11
Figure 12-10 shows a screw base neon lamp with shaped shows a straight neon tube. The plasma will extend over the
electrodes. The electrodes can take any shape that will fit into entire length of the tube between the electrodes.
Another attribute of the plasma is that it will form around
curves and bends in the tube. An open sign, as shown in
Figure 12-12, is actually a single tube bent into the shape of
the word. The connecting parts are blacked out and when the
Neon Gas
tube is energized the letters glow brightly.
Electrodes

Glass Bulb
Blacked Out Sections

Glass Tube

Terminal Wires

Figure 12-9 Neon Lamp Terminal Boot
High-Voltage Wire
To Transformer
Figure 12-12 Commercial Neon Lamp

Neon Gas

High voltage is required to start a neon tube because the
electrodes are so far apart. A current-limited transformer, as
shown in Figure 12-13, is typically used for these applica-
tions. The open voltage of the transformer is usually in the
20,000- to 45,000-volt range. When the voltage is applied to
Glass Bulb Electrodes
the electrodes, electrons flow from one electrode to the other.

High-Voltage Terminal
Electrode Wires Insulator Label
Case

Screw Base
115/120 VAC, 50/60 Hz. Input Terminals

Center Terminal Mount Tabs
Figure 12-10 Shaped Electrode Neon Lamp Figure 12-13 Commercial Neon Sign Transformer