How do Neon Sign Transformers Work?

Neon signs are commonly used for advertising and decoration. The neon sign transformer is the heart of these attractive signs, and here we shall learn about its working.
Neon sign transformers provide the high voltage required to illuminate the attractive neon signs, which are used widely for advertising and publicity, in theaters, hotels, and auditoriums.

Working Principle
  • Neon signs use neon gas that is inert in nature. These signs are made up of tubes that are filled with this gas.
  • This tube is supplied with high voltage obtained from the transformers. The high voltage supplied by them increases the kinetic energy of electrons in the neon atom.
  • The atom is ionized when the kinetic energy of electrons is high enough. Ionization develops a positive charge or a negative charge on the atom. These charged atoms create plasma that carries the electricity from one end of the tube to another. The plasma formed in this process completes the electric circuit and causes the electrons in the atom to fall down to their regular levels from the excited state.
  • As the electrons return to their regular energy levels, a photon is emitted. This photon illuminates the neon signs.
  • The basic principle is that high voltage must be provided to the neon gas for illumination. This high voltage is provided by the transformers.
Transformers are generally used for increasing (step-up) or decreasing (step-down) the voltage, as per the demands of an application. The signs require a high voltage, so a step-up transformer is used to light them up. It has a primary winding and a secondary winding. These are wound on an iron core and the primary winding is connected to the mains, while the secondary is connected to the equipment. The secondary winding provides the necessary high voltage that ranges from 2 to 15 kV. The line voltage has a range of 120V to 240V and the output current ranges from 30 mA to 60 mA.

The intensity of the neon lights varies, when the voltage supplied to the neon tube is varied. The line voltage supplied to the primary winding is varied in order to vary the output at the secondary winding. The secondary winding provides a variable voltage depending on the intensity required. The transformers are generally center-tapped. In a center tapped one, the secondary winding has a third lead at the center. This center tap is grounded and the voltages at the output of the other two ends, are out of phase with each other. These voltages are measured with respect to ground voltage, which is provided by the center tap.

The disadvantage of the center tapped transformers is that the voltage at the output is half of its actual voltage rating. However, this does not affect the signs. They are used as a voltage supply for many high-voltage experiments. In these experiments, the full potential is not utilized due to the center tapping of the secondary winding. In many other applications, the center tap is removed to utilize their full potential.

Nowadays, signs are available in different colors, as the gas used in them is different. Different gases like argon, xenon, helium, mercury, and carbon dioxide are used to make these signs in different colors. Variations in colors make the advertisements eye-catching. You just need to plug-in the transformers to the neon tubes. Unlimited creativity can help you develop showy and attractive signboards.