The Numitron: The attractive but underachieving little brother of the Nixie tube.
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- Опубликовано: 2 июл 2024
- More Soviet-era display antics with Numitron tubes. Filmed while I wait for the next revision of my driver board for the neon plasma display.
Numitrons were invented in the late 1960's by RCA in the USA. They didn't see a huge amount of use as they were quickly superceded by LEDs. However, they were manufactured en-masse in the Soviet Union and new, unused tubes are still available today in Ukraine, Latvia and other ex-Soviet countries.
Here I built a device to help me monitor training runs for neural networks, along with displaying the weather....and anything else I want to display.
Since I never mention it in the video, the driver chips are TPIC6B595. The full schematics are available at the linked github repo below.
Chapters:
0:00 Introduction
0:43 History of Numitrons
2:15 Pros and Cons
5:42 How I'm using them
8:52 My Design
12:03 Lifetime Considerations
15:04 Final Thoughts
Source code for ESP32, and PCB design:
github.com/lambdaBoost/iv-9_k...
Custom callback for Keras to send metrics over to API. Dockerfile for API server included:
github.com/lambdaBoost/simple...
Sources:
Inspiration and some info on filament lifetime:
www.dos4ever.com/numitron/num...
RCA Engineer; May 1972. Contains extensive info on RCA numitrons:
worldradiohistory.com/ARCHIVE...
Outstanding series on the CED (it sounds like I say 'CD' in my video because of my terrible accent). Developed at the same time as numitrons and contributing to the collapse of RCA:
• The CED: RCA's Very La...
More info on the cabinet with numitron score indicators:
www.arcade72.com/allied-hesit...
Lamp rerating:
en.wikipedia.org/wiki/Lamp_re...
Absolutely idiotic and unhelpful response to a reasonable question about design voltages. This is from more than 10 years before I filmed this but I came across it in my studies. Leaving it here as and a 'don't be this guy' tale. (for clarity, the chip does work at 3.3v):
forum.sparkfun.com/viewtopic....
The reason why these bad boys were not used that much is that these display technologies were developed made for military purposes - showing crucial information that need to be absolutely reliable. With nixies this is perfect because they have extremely low failure rate if driven properly. And if they fail, either a digit doesn't light up - immediately noticable - or parts of it don't light up - also noticable. There's no scenario where you can mistake partially lit digit for another digit. Now numitrons are 7-segment and incadescent. Incadescent fails alot (in numitron there are 7 separate filaments to fail!) and since it's a 7-segment, if one segment fails, it can easily be mistaken for a different digit (let's say you have number 8 and middle segment fails -> suddenly you have 0). This is unacceptable for anything remotely implortant. And that's where 7-segment VFD displays come into play, from the way they work, it's virtually impossible for individual segments to fail - they gradually get dimmer as they age, which is fine. If a VFD fails, it fails completely - broken vacuum seal, or it just get very dim with time. VFDs are very resilient and can be used in deep freezing temperatures where other displays fail. This is why they are used still today.
Ok so this is absolutely true but application-specific. For less critical applications such as gas pumps (where numitrons were used extensivley), an ambiguous segment failure is better than total failure. As some other commenters have pointed out, numitrons were also far better solution in vibration-sensitive applications; such as aviation. The development of the Apollo DSKY display is an intersting example - nixies were ruled out due to low vibration tolerance. Numitrons were investigated but ruled out due to the reasons you point out plus their relativley poor readability. The chosen option was a 7 segment electroluminescent display driven by relays: even for something as critical as the Apollo guidance computer, it was decided that viewability took precedence over a single segment failure (video on this coming soon!).
As you say, VFDs later went on to solve these issues.
Thank you. I wondered why they weren't more popular as I would expect them to have been much easier and cheaper to produce. This does make a lot of sense. I didn't even consider the implications of a single segment failing on a Numitron.
1:40 Nixie tubes were very easy to use with mechanical switches in for example elevators. The high voltage wasn't an issue, as most devices were mains powered and a transformer could easily have an extra winding for the nixie voltage rail. 7 Segment displays like the Numitron probably only became viable with the advent of integrated circuits. If you had to implement a discrete BCD to 7-segment decoder you needed 7 transistors and more than 50 diodes per digit. RCA marketed the Numitrons with the needed driver chips that became available at the same time.
They were probably a lot more expensive than Nixie tubes (and high voltage 7-segment "nixie" tubes) at the time, that is why you don't see them in any calculator of the early 70s.
RCA marketed them even up to 1974 with these advantages : Sunlight readable, unlimited colour filters, controllable brightness, 100000 hour life expectancy, low voltage operation, wide viewing angle, wide operating temperature range, shock and vibration resistant.
Amazing, thanks for the clarification. I suspected the more complex logic required for 7 segment displays was the reason for nixies being dominant for so long.
The thought of driving these with discrete components is not fun!
It's also interesting you mention sunlight readability as an advantage. That's something I'd noticed myself but didn't mention in the video. When I get direct sunlight onto my desk, I can read the numitrons but not my nixie clock.
I love IV-9's! I was buying them 50+ at a time for a few years when I was selling IV-9 clock kits back when they were cheap. Sadly the supply seems to have dried up on them a little bit.
And I remember reading that these had better vibration resistance than Nixies, so that made them better suited for some purposes.
The prices shot up during covid. I think a lot of people like me found themselves at home and decided to take up electronics as a hobby. Then obviously the Ukraine war hasn't helped either since they can no longer be imported from Russian sellers.
Ah vibration resistance that's a great point - all those cathodes and little dividers in nixie tubes could come loose quite easily.
I think numitrons were originally designed to be run from TTL logic, which had a stabilised 5V power supply where varying brightness wasn't a problem with them.. And they're very easy to drive using a 7447 BCD to 7-segment decoder, with no other components needed.
They were a frequent sight on UK garage forecourts as well in 70s and 80s, in Gilbarco Highline fuel pumps.
I didn't realise they were common over here too. If I didn't happen to have this niche hobby, I'd probably have gone my whole life without even hearing of them.
@@Alexander-the-ok I've always had a niche interest as well in old display technologies, otherwise they'd have just been digits telling me the price and how much petrol I was putting in my car.
I'm one of the very few who wears a nixie tube watch to know the time of day. :D That's something that was totally unheard of back in the '60s when nixies were most common, and quite often used in expensive scientific instruments.
Back in the 50s and 60s, there was many different technologies used to display numbers. Things like nimo tubes, that were little CRTs that required 4kV to make them work. Projection displays using incandescent illumination, were quite common.
just come across your channel i have several numitron tube clocks they are a lovely tubes got two clocks runing DTF 104B
I had to google but the 104Bs look amazing! Its funny how all these tubes were designed to be purely functional but 50 years later we’re drawn to them because they look pretty.
Earned my sub, excited for more vintage display tech vids :>
Thanks! More on the way soon - I've just recieved the PCBs for my next video.
Cool and interesting video, I didn´t know the Numitron, thanks!!!
Nice video, very informative! Never really thought about how numitrons came about after nixies even though the underlying technology is much older. Can't wait for the next video.
Thanks. The only theory I could come up with is the logic for 7 segment displays is slightly more complex than nixies which can just be driven with a decimal counter.
The timing/content of my next video will depend on my SMD soldering skills!
@@Alexander-the-ok indeed, I think the whole reason why nixie were prevalent much earlier was for their decimal nature, while 7segments mandatorily requires decoding logic.
Mind that, while today we can think very easily of a diode matrix to perform that decoding, back then when nixies were the "go to" choice, semiconductor diodes were not widely available and, when they did become available they weren't initially cheap, and perform this decoding requires a lot of diodes.
@@fabiotrevisan8922 Yep, I find it hard to imagine a world where ICs didn't exist! In fact, discrete transistors had barely been made commercially available when nixies were first sold. All really difficult for me to imagine.
Can't ever watch a tech video without RCA's CED fiasco making an appearance/mention
You still see the DIP packaged cousins of Numitrons- known as Minitrons- used in older avionics.
I was wondering about your soldering - you need to improve that a lot. What solder are you using?
The soldering on this board is complete garbage. I didnt have my solder station available at the time so it was done with a cheap iron. Also had to remove the microcontroller at one point which really messed things up
I have a dozen of the iv-9's and have been thinking of how to implement something similar. I'm either going to try the Microchip Technology HV518P-G or the Maxim Integrated MAX6921AWI.
I may well be wrong here but, looking at the data sheets, I'm not sure those VFD driver chips would be able to source enough current per pin. I used TPIC6B595 chips in my design (though they were also technically out of spec since they are designed for 5v logic, so vfd driver chips may work too)
@@Alexander-the-ok I highly recommend the TPIC6B595 for driving Numitrons.
Why not just use ULN2003 chips with 595 shift registers? Multiplexing becomes safe if you run them with a discrete logic counter instead of software.
Also I was always under the impression that numitrons were cold-cathode 7-segment displays, shows how much I know.
Firstly, congrats on the titan video. Secondly, thought I’d comment here, as maybe you’d actually see it.
The picture of the CEO, where he’s holding the controller, it appears he screwed the monitor mounts directly to the carbon fiber hull? Wouldn’t that mess with the integrity of the hull as well?
Are you talking about the OceanGate Titan submarine video?
@@Yxcell yes
Hello, will there be a continuation for the MC6205 monitor (GIP-10000) ?
Hi. Absolutely! It's been a really difficult project but I've designed and ordered the new anode-driver PCB (finding ICs to drive the anodes was really difficult and I'm onto rev3 of the driver pcb!). So I'll be testing them out in the next few weeks. I hope to have a video on that project released within the next month.
@@Alexander-the-ok Can I talk to you on the side, mail or some message ?
@@leooel4352 go ahead - you can contact me at enquiries@alex-hall.co.uk
8:41 You mean to say the Soviet vehicles losses, right?