Nixie Tube

The Nixie tube, also called a counting tube, is a gas discharge tube used to display information. It is the predecessor of the light emitting diode and the liquid crystal display, both of which use less power and last longer than the Nixie tube. Although they are still made today, Nixie tubes have largely disappeared from modern electronics.

History

The idea of using a gas discharge to display information first appeared in the 1920s, but it wasn't until the 1950s that Nixie tubes became widespread. The term is actually a trademark of the Burroughs Corporation that has become a generic name.

Components

The Nixie tube consists of a sealed glass container with a mesh anode and several cathodes, usually shaped in the form of numbers. They are surrounded by a Penning mixture of one noble gas and a small amount of other gases. This mixture is more efficient than a pure gas because it has a lower striking voltage. At the base of the tube is a set of contacts, one each for the anode and the many cathodes.

Operation

To create the gas plasma around the cathode, there needs to be a potential difference of greater than 150 volts between the cathode and anode. This is called the striking voltage. When one current begins to flow, the potential difference required to maintain the plasma falls between twenty and thirty volts. The Nixie tube is called a cold-cathode tube because it doesn't require a heated cathode, unlike regular valves which get very hot and use a lot of power. It has the same distinctive flickering orange glow as a neon tube.

Applications

The main use of Nixie tubes was to display numbers in meters and counters. They were also used in the elevators, calculators, signs, and many other devices. Their fragility, high power usage, and high voltage compared to light emitting diodes are the main reasons for the demise of the Nixie tube. However, the Nixie tube has gained popularity recently with hobbyists trying to create a nostalgic look to their projects.