With the popularity of Nixie clocks, we’d be forgiven for thinking that the glowing tubes are only good for applications with a stately pace of change. But we forget that before they became the must-have hobbyist accessory, Nixies were used in all kinds of scientific instruments, from frequency counters to precision multimeters. In such applications, update rates in the hundreds or thousands of Hertz aren’t uncommon, and the humble Nixie handled display refreshes with ease.
But what about refreshing a Nixie at 100 kHz? That was the question put to artisanal Nixie maker [Dalibor Farný] by a client who wanted a timer to calibrate high-speed cameras. It was a feat that [Dalibor] wasn’t sure his custom-made tubes could handle. The video below shows his efforts to find out.
If you ever wanted to know about the physics of gas-discharge displays like the Nixie, the fifteen minutes starting at about 5:13 will give you everything you need. That basic problem boils down to the half-life of excited neon, or how long it takes for half the population of excited molecules to return to the ground state. That, in turn, dictates how long a given cathode will continue to visibly glow after it’s turned off, which determines how many digits will appear illuminated at once.
To answer that, they engaged a company in Prague with a camera capable of a mind-blowing 900,000 frames per second. Even though they found a significant afterglow period for each cathode, even at 100 kHz it’s clear which digit is the one that’s currently illuminated. They also looked at the startup of digits in a cold Nixie versus one that’s warmed up, leading to some fascinating footage at around 26:30.
We appreciate [Dalibor]’s attention to detail, not only in the craftsmanship of his custom tubes but in making sure they’re going to do their job. He recently did a failure analysis on some of his high-end clocks that showed the same care for his product and his brand.