Zbudowano przenośny tester lamp Nixie zasilany z USB do sprawdzania LC-513 i LC-516 przed zakupem.
ATmega8 steruje katodami i pracuje też jako przetwornica boost, podnosząc 5V z USB do wysokiego napięcia.
Przetwornica pracuje z PWM 31.2 kHz, wypełnieniem 85% i osiąga około 180V przy sprawności prądowej około 1.2 mA.
Tester pozwala automatycznie lub ręcznie przełączać cyfry, a po podłączeniu do PC odczytuje napięcie i wykrywa uszkodzone lub nadmiernie prądowe katody.
Pierwsze uruchomienie starych lamp często wygląda słabo przez cathode poisoning, a niektóre oprawki, zwłaszcza dla LC-516, są mechanicznie niewygodne.
Summary generated by AI based on the discussion content.
Motivation 8 years after mine last project I once again had the urge to build another Nixie clock. And as we know, lamps are an essential element of every such clock. They no longer produce such lamps (except for a few cases of hobbyists who bend numbers from wires in the privacy of their homes, encasing the whole thing in hot glass. So the only way is to buy some old copies from private people.
Purchasing used electronic components on aliexpress taught me that you should never trust and always check (test). The same may probably be true with lamps, but surprisingly these are easiest to get not in the Far East, but in our closer eastern neighbors (Ukraine, Russia). So I decided to build a handy lamp tester, powered by USB (!), so that I could, for example, connect it to a power bank and take it with me to a flea market before buying lamps.
The most popular in our country are probably the lamps from the domestic company DOLAM: LC-513 and LC-516. The latter are basically the same as the former, but covered with resin in the plinth. I heard that some people have the ability to cut this ebonite "filth" and remove the lamp. But in the "clothes" both lamps have different pinout, so I decided to create two testers.
Description of the device The whole thing is managed by the only integrated circuit on board: Atmega 8. And it`s not boring at all, because in addition to controlling the cathodes, it also serves as a voltage converter. And it`s not easy - increasing 5V from USB to 180V was implemented in the form of a simple Boost converter. PWM frequency is 31.2 kHz, duty cycle is 85%. The increased output voltage is monitored by the microcontroller with one of the ADC inputs, thanks to which the feedback keeps the output voltage at a set level. Although I tested even without feedback and in this system I was not able to get more than about 180V (without load). Maximum current efficiency approx. 1.2 mA.
The microcontroller is clocked with an external 16 MHz crystal for USB purposes - because the system uses USB not only for power, but also has the ability to communicate with a computer. Using a PC, you can, for example, read the voltage produced by the converter when powering various cathodes, so you can detect, without looking, which of the cathodes have any problems (e.g. they do not light up at all or consume excessive current).
There is also a button - by default, when turned on, the device displays each digit in a circle. However, by pressing the button you can change the control to manual, thus keeping a given digit longer.
As a socket for the LC-513 lamps, I used extended connectors from the DB socket. They work perfectly.
DownI used a dedicated stand for the LC-516 lamp, but I am not satisfied with it - quite a lot of force is needed to place the lamp in it.
And finally, a comparison of both testers - it is basically an identical design, the difference is only in the upper part of the board on which the tested lamp is placed. Thanks to the use of SMD elements, the device is very small and handy. Some more casing would be useful...
As an interesting fact, it took me half a day to build the second one - the microcontroller was unable to generate high voltage, it reset itself if I changed the fill factor in the interrupt function. After replacing it with another identical chip, the problem disappeared. Heh, now it`s time to create an atmeg tester from aliexpress.
I noticed that most of the lamps, when turned on for the first time after many years, glow "sluggishly" - some of the digits seem to have missing fragments. Only after a dozen or so seconds everything starts to "normalize" and the lamp, put aside and then tested, e.g. after an hour, works normally. So it is not some form of "heating up", but rather a phenomenon known as cathode poisoning - some oxides are deposited on the cathodes, which are "dusted" back from them only after some time. Apparently, when displaying digits on such lamps, it is worth displaying all the digits one by one from time to time to eliminate this phenomenon.
Attachments:
nixie-tester.zip(108.31 KB)
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About Author
phanick wrote 2949 posts with
rating 2834 , helped 65 times.
Live in city Warszawa.
Been with us since 2007 year.
Cool project - I would love to see a version in the form of one board and plug-in adapters depending on the lamp being tested
I must disagree with this statement ;-)
Below are the website addresses... [Read more]
gulson
30 Nov 2023 12:23
Thanks for sharing your project. If you send me a parcel locker, I will give you a small gift! [Read more]
CMS
01 Dec 2023 17:30
An interesting phenomenon. But where do the oxides come from if it s something else. Maybe my colleague @AlekZ will say something more about this interesting topic. [Read more]
phanick
02 Dec 2023 00:02
The current appearance of the project does not exclude the use of adapters - they will have male DB contacts in the shape of a circle (like contacts in a lamp), instead of "goldpins".
People designing... [Read more]
pawelr98
03 Dec 2023 02:18
Not true.
Dalibor Farny, and additionally a milclock factory in Ukraine.
The former makes new models of nixie tubes from scratch. This second factory only produces one type, the modernized IN-18 as... [Read more]
CMS
03 Dec 2023 14:14
We`re talking chatter here, and Tiktok gave me this beauty [Read more]
behru
04 Dec 2023 13:29
Well, I wrote it in the first post, which was a comment on the author`s entry :D [Read more]
cirrostrato
04 Dec 2023 13:59
I had a lot of new Z573M (not as big as IN-18), I sold one collective package (200 pieces) with difficulty two years ago for PLN 20/piece, now even PLN 35/piece for these NEW IN PERFECT CONDITION NIX,... [Read more]
jaeger
11 Dec 2023 13:38
This is a gas lamp, a neon lamp to be precise.
Perhaps it would be enough to reduce the lamp current, e.g. by increasing the value of the anode resistors?
Reducing the voltage will not necessarily... [Read more]
FAQ
TL;DR: This USB Nixie tester boosts 5V to about 180V and, in the builder’s words, is “powered by USB (!)”. It helps clock builders and flea-market buyers test LC-513 and LC-516 tubes from a USB port or power bank, hold digits manually, and use PC readouts to spot weak cathodes before purchase. [#20839537]
Why it matters: A pocket-size tester reduces the risk of buying old Nixie tubes with weak digits, bad pin contact, or unstable behavior after long storage.
Option
Main benefit
Main drawback
Best fit
Extended DB contacts for LC-513
Works “perfectly” as a socket
Tube-specific layout
Compact LC-513 tester
Dedicated LC-516 stand
Ready-made mechanical fit
Needs quite a lot of force
LC-516-only tester
Thicker single pins from AliExpress
May improve insertion feel
Not yet implemented
Future LC-516 revision
Plug-in adapters on one main board
One core tester for many lamps
Needs lamp-specific adapter heads
Multi-tube platform
Key insight: The clever part is not just the 180V boost stage. One ATmega8 handles both high-voltage generation and cathode control, making a genuinely portable Nixie tester practical from plain USB power.
Quick Facts
The tester uses an ATmega8, an external 16 MHz crystal, and a simple boost converter that raises 5V USB to about 180V. [#20839537]
The boost stage runs at 31.2 kHz PWM with about 85% duty cycle and reaches roughly 1.2 mA maximum output current. [#20839537]
The default mode cycles through all digits automatically, and a button switches to manual mode so one digit can stay lit longer for inspection. [#20839537]
The builder observed that some stored tubes look weak for a dozen or so seconds before normalizing, which he linked to cathode contamination effects. [#20839537]
In a six-tube multiplexing discussion, the reported brightness drop was small in practice: digits became thinner, but not 6× dimmer, and the purple background glow decreased. [#20842287]
How does this portable USB Nixie tube tester generate about 180V from a 5V USB supply using an ATmega8?
It uses the ATmega8 as both controller and boost-converter driver. "Boost converter" is a DC-DC converter that raises a low input voltage to a higher output voltage by switching an inductor, storing energy in pulses, and releasing it at higher potential. Here, the microcontroller drives a simple step-up stage from 5V USB to about 180V, monitors the output with an ADC input, and closes the feedback loop in firmware. The reported PWM settings are 31.2 kHz and 85% duty cycle. [#20839537]
What is cathode poisoning in Nixie tubes, and why do digits sometimes glow sluggishly or show missing fragments after many years of storage?
Cathode poisoning is a contamination effect that makes some digits start weakly, with missing segments or uneven glow. The builder saw old tubes recover after a dozen or so seconds, then work normally even when retested an hour later. He described deposits on the cathodes being cleared during operation, and suggested briefly cycling through all digits from time to time to reduce the effect. That matches his observation that first-start behavior improved after short use. [#20839537]
Why does an external 16 MHz crystal matter for an ATmega8-based USB Nixie tester?
The external 16 MHz crystal matters because the tester uses USB for communication, not only power. The builder states the ATmega8 is clocked from a 16 MHz crystal specifically for USB purposes. That stable clock lets the device talk to a PC, where the user can read converter voltage under different cathode loads. Without that PC link, the tester would lose one of its main diagnostic functions. [#20839537]
How can I use a PC connection to diagnose weak or faulty Nixie cathodes by monitoring converter voltage and current behavior?
Use the PC link to watch how the converter voltage changes when each cathode is powered. The builder says the computer can read the generated voltage while different cathodes are lit, which lets you detect digits that do not light at all or draw excessive current. In practice, compare the readings digit by digit. A cathode with abnormal behavior will stand out from the others without needing visual inspection alone. [#20839537]
What are the pinout and socket differences between DOLAM LC-513 and LC-516 Nixie tubes when building a tester?
The LC-513 and LC-516 are similar lamps, but their pinouts differ when the LC-516 remains in its resin-covered base. The builder says the LC-516 is basically the same lamp, yet “in the clothes” both lamps have different pinout, so he made two testers. That means one common PCB top section is not enough unless you add lamp-specific adapters or socket wiring for each pin circle. [#20839537]
Which socket solution works better for an LC-513 or LC-516 tester: extended DB connector contacts, a dedicated stand, or thicker single pins from AliExpress?
Extended DB connector contacts worked best for the LC-513 in this build. The builder says they “work perfectly” as the LC-513 socket. He was not satisfied with the dedicated LC-516 stand because insertion needed quite a lot of force, and he pointed to thicker single pins from AliExpress as a likely future replacement. For this thread, DB contacts are the proven choice, while the thicker pins are the planned improvement. [#20839537]
How do you build a small portable Nixie tube tester that can run from a USB power bank for flea-market lamp checking?
Build it around a USB-powered ATmega8 board with an onboard 180V boost stage and a tube-specific socket. 1. Use 5V USB input and step it up to about 180V with firmware-controlled PWM. 2. Add a button for auto-cycle and manual digit hold. 3. Fit a compact socket section for the target lamp, such as LC-513 or LC-516, and power it from a USB port or power bank during buying checks. The builder explicitly wanted a tester small enough for flea markets. [#20839537]
Multiplexing vs separate control for Nixie clocks: which gives better brightness, simpler hardware, and potentially longer tube life?
Separate control gives higher brightness, while multiplexing simplifies hardware. The builder notes multiplexing saves driver I/O pins and transistors, but with six lamps each tube is active for only 1/6 of the time. Separate control lights all tubes at once, yet it needs a more powerful high-voltage converter because current demand rises about sixfold. He also raised tube life as an open question, asking whether multiplexing shortens life, but the thread does not settle that part. [#20842287]
Why doesn't multiplexing six Nixie tubes reduce apparent brightness by a full six times in practice?
Because perceived brightness does not scale linearly with duty cycle in this test. The builder compared 1/1, 1/2, 1/3, 1/4, 1/5, and 1/6 on-time and reported that brightness decreased only slightly, not by a full factor of six. He observed thinner-looking numerals at shorter on-times, but also less purple background glow. So multiplexing can preserve much of the visual brightness even when each tube is lit for only 1/6 of the cycle. [#20842287]
What is a boost converter, and how is it used in a Nixie tube power supply to step 5V up to around 180V?
"Boost converter" is a DC-DC converter that raises a low supply voltage to a higher one, using switching pulses, an energy-storage element, and controlled feedback to hold the target output. In this tester, it converts 5V from USB into about 180V for the Nixie anode supply. The ATmega8 generates the PWM drive, and one ADC input measures the high-voltage output so firmware can keep it near the set level under load changes. [#20839537]
What is a neon gas-discharge lamp, and how is it different from a vacuum tube in the context of Nixie displays?
A Nixie is treated here as a neon gas-discharge lamp, not a vacuum tube. "Neon gas-discharge lamp" is a gas-filled display device that lights shaped cathodes by ionizing gas around them, unlike a vacuum tube that operates without a working gas fill. One participant directly corrected the vacuum assumption and wrote, “This is a gas lamp, a neon lamp to be precise.” That distinction matters when discussing glow behavior, startup effects, and cathode surface conditions. [#20856317]
Where do the oxides or deposits on Nixie cathodes come from if the tube is not a vacuum tube but a gas-filled neon lamp?
The thread does not fully resolve the source, but it does challenge the vacuum assumption. One participant asked where oxides would come from if the tube were a vacuum tube, and another replied that a Nixie is actually a neon gas lamp. So the practical takeaway is narrower: the builder observed cathode-surface contamination effects, but the chemistry behind those deposits was not explained conclusively in the discussion. [#20856317]
What could cause an ATmega8 in a Nixie tester to reset when the PWM duty cycle is changed inside an interrupt routine?
In this build, the immediate cause was a bad microcontroller. The builder spent half a day on a second tester because the ATmega8 could not generate high voltage and reset itself when he changed the fill factor inside the interrupt routine. After he replaced it with another identical chip, the problem disappeared. That makes the edge case clear: repeated resets during PWM updates can come from a faulty MCU, not only from firmware design. [#20839537]
How can plug-in adapters be designed so one main tester board can support different Nixie tube types and pin circles?
Use one main board and make the lamp head a removable adapter. The builder replied that adapters could have male DB contacts arranged in a circle, matching the lamp contact pattern, instead of standard pin headers. That approach keeps the boost converter, ATmega8, button, and USB interface on one compact base while swapping only the top socket geometry for each tube family. It is the cleanest path from two fixed testers to one expandable platform. [#20842287]
Where can I still buy newly manufactured Nixie tubes like Dalibor Farny models or Millclock ZIN-18, and how do they compare with vintage tubes from private sellers?
The thread names Dalibor Farny and Millclock as current sources of newly made Nixie tubes. One participant says Dalibor Farny makes new models from scratch, while Millclock produces a modernized IN-18 called the ZIN-18. The same post gives a concrete price point of $99 for one ZIN-18 and compares that with vintage IN-18 tubes at roughly PLN 200–400 per piece on the secondary market. That puts new and vintage options in a similar cost band for large tubes. [#20843809]
Summary generated by AI based on the discussion content.
Comments
Cool project - I would love to see a version in the form of one board and plug-in adapters depending on the lamp being tested I must disagree with this statement ;-) Below are the website addresses... [Read more]
Thanks for sharing your project. If you send me a parcel locker, I will give you a small gift! [Read more]
An interesting phenomenon. But where do the oxides come from if it s something else. Maybe my colleague @AlekZ will say something more about this interesting topic. [Read more]
The current appearance of the project does not exclude the use of adapters - they will have male DB contacts in the shape of a circle (like contacts in a lamp), instead of "goldpins". People designing... [Read more]
Not true. Dalibor Farny, and additionally a milclock factory in Ukraine. The former makes new models of nixie tubes from scratch. This second factory only produces one type, the modernized IN-18 as... [Read more]
We`re talking chatter here, and Tiktok gave me this beauty [Read more]
Well, I wrote it in the first post, which was a comment on the author`s entry :D [Read more]
I had a lot of new Z573M (not as big as IN-18), I sold one collective package (200 pieces) with difficulty two years ago for PLN 20/piece, now even PLN 35/piece for these NEW IN PERFECT CONDITION NIX,... [Read more]
This is a gas lamp, a neon lamp to be precise. Perhaps it would be enough to reduce the lamp current, e.g. by increasing the value of the anode resistors? Reducing the voltage will not necessarily... [Read more]