Did you know that long before LED and Vacuum fluorescent displays were invented, tubes were used to display the numbers in early computers, calculators, and electronic test equipment? These unique tubes are called Nixie Tubes. Unlike tubes we use in audio circuits and power supplies, these tubes have a cold cathode. This means they do not need heat for their cathodes to function and rarely get much warmer than room temperature. As well, they are actually not vacuum tubes at all, but rather filled at low pressure with neon gas mixed with some amount of argon and/or mercury. Inside a typical Nixie tube you’ll find ten cathodes, each shaped like a number. The there is one cathode for each digit from 0 to 9. When voltage is applied between a specific cathode and the tube’s anode the cathode is ignited making it’s digit shape brightly displayed.
As electronics evolved and new technology brought the LED and Vacuum fluorescent displays for common calculators and electronic measurement meters, the need for large bulky nixie tubes faded quickly. Since then it has been electronics enthusiasts, artists, and tube lovers (like us) who have brought back this obsolete technology. Today you can find all sorts of clocks, alarm clocks, watches, thermometers, and other devices using nixie tubes.
Feature Image: A Steampunk Nixie Clock by TGT Studios