What is a neon sign and how does it work?
A neon sign is a very simple device. It consists of a vacuum-tight glass tube, fitted at each end with an electrode. Inside the tube is a small amount of rare gas. Connected to the two electrodes is a source of high-voltage electrical power. When the current is turned on, the tube glows with a steady piercing light.
The rare gases, neon, argon, helium, xenon and krypton, are ideally suited for use in signs. The two most common gases used in neon signs are neon and argon. While neon is very bright, argon's light is weak due to its low resistance.
Neon gas gives off a red glow. This gas is normally contained in tubing that is clear in color, and when illuminated, projects the brightest red color.
Almost everything else is filled with argon gas. When you see yellow, blue, green, white or any of several other shades, these tubes are filled with argon gas.
Tubing Diameters or Size
Neon tubing comes in various diameters depending upon the application. The tube diameter or size is calculated in millimeters and typically runs from 8 - 11 mm for use in indoor signs and 12 - 13 mm in diameter and for use in large indoor neon signs or outdoor signs and channel letters.
Smaller neon tube diameters are easier to bend into written works but are not as distinguishable from a distance. Larger tube diameters are more visible from a distance, and are more effective in illuminating store front letters, but cannot be practically formed into smaller written applications. Larger diameter neon tubing is less brilliant.
Colors and Coatings
Neon tubing can be created in many different colors, through the use of argon gas and the various internal phosphor coatings on the glass itself. The coatings in the tube appear to be white when non-illuminated. They become other colors once the tube is illuminated and the phosphors become excited. More expensive pigmented glass tubing can be purchased in order to achieve a richer color, such as Novial Gold or Ruby Red and a few others.
Every neon tube has two electrodes attached to it, one at each end of the tube. The electrical current enters the tube through the electrode which is comprised of a small metal thimble-like cup. The electrode is "welded" to the neon tube.
The two wires off the electrode are connected to the GTO cables leading from the transformer. This is a high voltage connection, and is covered by rubber insulative sleeves to ensure the user is not shocked.
PK Housings or Hage Connectors
On outdoor signs and channel letters, the GTO cable is not attached directly to the glass. Instead it makes contact with the glass through the use of either PK Housings or Hage Connectors.