Nixie type displays were superseded by Vacuum Fluorescent Displays (VFDs). The VFD was invented by a consortium of Japanese electronics manufacturers, so that they could stop paying the large royalties associated with Nixie tubes. VFDs use less power, and were not under patent - and so they eventually displaced the Nixie, which had always been considered too costly for consumer-grade electronics displays.
Below, a Vacuum Fluorescent Display (VFD)
VFDs were used alongside LEDs (Light Emitting Diodes) for about two decades. These in turn were both mostly replaced by LCD technology. The LCD (Liquid Crystal Display) is currently the go-to technology for consumer-level electronics displays - TV screens, calculators, computer monitors, watches, etc. Pretty much any modern numeric display is LCD. Most recording and playback devices currently use on-screen displays. Nowadays, a player might have only one LED light to indicate that the device is on. Technology marches on! I'll take up the rear, thank you very much...
So how does a Nixie tube work? Glad you asked! These are cold-cathode tubes. This means that unlike a normal vacuum tube, they do not require a heater. Instead, these operate more like a low-voltage neon tube that has a mild visible discharge at the cathode.
The tube is under partial vacuum, and the remaining gas is a neon and mercury vapor blend. The neon provides the light, and the mercury provides the reduced operating voltage. All of the numbers are made of fine wire, and are stacked on one another. The anode is the mesh grid beneath the numbers. Each number is a cathode that is electrically isolated from all the other numbers.
Below, an animation of a top-view Nixie tube going through its numeric sequence.
For a long time, I've had an app on my android phone to make the clock look like a Nixie display.
That's a cute phone display, but it isn't the real deal. Since I'm taking up hobby electronics, I decided that I would purchase a vintage General Radio 1192 frequency counter that contains a Nixie tube display.
Do I need a frequency counter? Not really. I have an oscilloscope that can display and measure waveforms with much higher frequencies than this counter can. It's just a cool retro gadget with easily repairable technology that happens to look very cool. Nothing wrong with that, is there?
So what good is a frequency counter in the first place? A frequency counter is capable of displaying the frequency of an input signal, up to its maximum design frequency. In addition to displaying radio frequency, these devices can also count up discrete events - if you are inclined to rig up an appropriate input device.
Possible inputs for counting might be closing a magnetic reed switch or interrupting a light beam. A nuclear scientist might have used this to count radioactive particle events from a geiger counter. It could easily count very rapid ionization events that would make the geiger counter speaker sound like pure static. For right now though, I'm just happy to bask in the deep orange glow of vintage Nixie tubes.
Below, just unpacked the treasure. The batteries are just there to show the size of the counter. As usual, the case is covered with cigarette tar stains. The front had already been cleaned to pretty it up for the online auction.
Testing the counter out in the kitchen. The auction stated that the second digit flickered. It still does. The bottom left switches are micro-switches. The unit is not large across the front. It is deep though.
On the work bench, with the cigarette stains removed. I need to find some time to remove the sticker adhesive from the front.
Yeah but will it be able to actually do what it's supposed to do? The real question... Can it tell you what frequency the signal is oscillating at??? Let's put a 15KHz wave on it and see what it does with it.
Good enough for me.
Fix-it stuff for this counter:
The flickering Nixie tube in the second position needs to be replaced. All I have to do is locate a NL-845 Nixie that hasn't been manufactured in several decades, and is a bit rare. EDIT: I found one, and it's on order.
I need to make or locate a short power cord. When I bench-tested it, I used a 25 ft outdoor extension cord for power, which is a bit too much cord for a work bench. This thing also has the most ridiculous power connector on the back. The plug is not inset into the machine, so the prongs are just hanging out there, ready to be bent over or crack the bakelite insulator.
The front input jack is corroded and seems to have plier marks on it. I'll soon be replacing this...
With this... I need to get it apart and see what the rear connection looks like first though.
Update: All three above issues have been corrected.
The flickering tube in the second position from the left has been replaced. I initially ordered a NL-845, because that's what I saw in the manual. When I opened up the case to replace the tube, it was considerably larger than the others. It was enormous! I decided to get a number off one of the other tubes and that number was B-5859S, made by Burroughs back in the day. National Electronics at one time made a similar tube called the NL-5859S, and that's what I was able to get. It's been installed and works just fine. The flickering is gone, and all the numbers work in the new tube.
The power supply cord I assembled from Home Depot parts. The cord was too long at 8 ft. I cut it in half, and then added the female end to the shortened cord.
The front BNC plug was not damaged by pliers. It was just so corroded that it looked like it had plier marks. It cleaned up well, and does not need to be replaced.
I have some dust caps on order to cover all the unused BNC plugs.
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