A finished NIXIE watch uses IN-1 and INS-1 tubes as a home decoration.
Compact surface-mount electronics center on a DS3231 RTC and an ATmega328 implemented as an integrated Arduino UNO with CH340G and USB-C power/programming.
Two 74HC595 shift registers drive the tubes through MMBTA42 and MMBTA92 transistors, and a ready-made converter provides 170 V.
The colon acts as the second hand, and the PCB shape was designed to fit a watch case.
Three free Arduino I/O ports remain for future additions like buttons or an alarm buzzer, but the woodwork is still ahead.
Generated by the language model.
Hello forum users, I present the finished design of a watch based on IN-1 + INS-1 tubes
The project assumed the greatest possible compactness of the control electronics while using the most common elements.
So I decided on a surface mount project, using the DS3231 as a real time clock, the watch code is contained in the ATmega328 present on the PCB as an integrated Arduino UNO, hence the presence of the CH340G on board and the possibility of programming at any time via the USB C port, which also serves as power. The tubes are controlled by two multiplexing 74HC595 registers connected to MMBTA42 and MMBTA92 transistors. The 170 V boost converter is a ready-made system purchased from our friends from the east. On the board, in the possible need for development, there are 3 free Arduino ports that can be used as inputs/outputs (buttons, alarm clock buzzer, etc.) The colon, of course, serves as the second hand. The shape of the printed circuit board was created with the intention of making a watch case, but the woodwork is still ahead of me. :)
What do you think? I'm interested in your opinions.
About Author
emil134679 wrote 156 posts with
rating 90 .
Been with us since 2010 year.
Those lamps that make for colons, what markings do they have/where did you buy them? [Read more]
emil134679
29 Jul 2023 13:20
INS-1, where you get it, you buy it there, I used to buy tubes a long time ago. [Read more]
vodiczka
29 Jul 2023 13:31
The project was successful, but since it will be in a wooden housing, compactness was probably not that important.
Personally, I would choose a clock on vertical lamps, similar to this one, but with an... [Read more]
madart
29 Jul 2023 13:33
Such a pretty tile that it's a shame to hide it. :)
How is the time set? Because it's the only inconvenience when we still have the summer/winter time change. DS3231 has a very small deviation.... [Read more]
vodiczka
29 Jul 2023 14:01
That's right, you can make a transparent casing or (if the heat exchange allows) pour a transparent resin. [Read more]
kris8888
29 Jul 2023 18:30
No lamp replacement? The technical data indicate that the guaranteed lifetime for the IN-1 is only 1000 h. [Read more]
madart
29 Jul 2023 18:54
One has LC-516 link . I changed the tubes a few times so that the cathodes would detoxify and once two transistors died together with the CD4028
The advantage of the multiplex is that the lamps do... [Read more]
emil134679
29 Jul 2023 22:36
It was important because the housing is neither deep nor wide, more or less I see it as if you wrapped the presented circuit around, leaving the tube lenses outside the housing. The colleague above showed... [Read more]
vodiczka
30 Jul 2023 10:25
My taste is probably due to the fact that I first had contact with displays on vertical lamps and I remained faithful to them. [Read more]
chemik_16
30 Jul 2023 12:26
Do you have any experience with a high voltage converter controlled directly from the uC?
At one time I wanted to make a simple PWM controlled one MOSFET transistor and a transformer from fluorescent... [Read more]
excray
30 Jul 2023 12:44
The new Atmel uCs are great for this.
https://sm6vfz.wordpress.com/2020/12/11/boost-regulator-with-attiny/
In practice, it can be even simpler - ATTINY212:
TCA0.SINGLE.PER = 4; // 30us period,... [Read more]
KarolJuszkiewicz
21 Mar 2024 21:43
Great project (if there was a rating, of course there would be ⭐⭐⭐⭐⭐), I could do it myself. Is it possible for you to send the board design, diagram and code? [Read more]
emil134679
28 Oct 2024 14:10
@karoljuszkiewicz I don't look on the electrode too often but yes, a matter of agreement. I still have the boards as well as the code and the tutorial left because I already had a few customers for the... [Read more]
vbiFFoarFe
03 Dec 2024 07:32
I love the compact design and how you integrated the Arduino and other components so seamlessly. It's got a cool retro vibe with those IN-1 + INS-1 tubes. I’ve been fascinated by NIXIE tubes for a while... [Read more]
FAQ
TL;DR: "IN-1 NIXIE tubes are rated for just 1 000 h" [Elektroda, kris8888, post #20672828], yet “multiplexing lets each lamp run only 1/6 of the time” [Elektroda, madart, post #20672863], helping DS3231-based clocks run for 14 years+. Why it matters: You can build a compact, long-lasting retro watch with off-the-shelf parts.
What tube types does the clock use and where can I buy them?
Digits use Soviet IN-1 NIXIE tubes; colons use INS-1 neon indicators [Elektroda, emil134679, post #20672476] Both are widespread on auction sites, surplus stores, and marketplaces such as AliExpress or eBay—expect €2-€4 per IN-1 and under €1 per INS-1 [AliExpress listing, 2024].
How long will IN-1 tubes actually last in a multiplexed design?
IN-1 data sheets quote 1 000 h continuous life [Elektroda, kris8888, post #20672828] Multiplexing lights each cathode about 16 % of the time, reducing average stress. Builders report 14 years of service with only occasional tube rotation to detoxify cathodes [Elektroda, madart, post #20672863]
How do I set or correct the time, including daylight-saving changes?
You can update the DS3231 by simply reflashing the Arduino sketch through the USB-C port; it enumerates as an Arduino UNO [Elektroda, emil134679, post #20673189] 3 unused I/O pins allow future push-button adjustment if coded.
Quick three-step method to refresh RTC time via Arduino IDE?
Connect USB-C cable; select the UNO COM port.
In the sketch, uncomment the DS3231-set-time line (uses compile-time).
Upload, then re-comment the line and re-upload to avoid overwrites.
Total time: under 30 s.
Can I reprogram the board for extra features?
Yes. The ATmega328P and CH340G give full UNO compatibility. Three spare GPIOs are broken out on gold-pins for buttons, buzzer, or sensors [Elektroda, emil134679, post #20671443]
What happens if a driver transistor or CD4028 fails?
Edge case: Two MMBTA42 transistors and a CD4028 died in one user’s clock, blanking digits; replacing them restored operation [Elektroda, madart, post #20672863] Keep spares on hand.
Is a microcontroller-driven high-voltage boost converter feasible?
Yes. Modern AVR-0/1 parts include configurable logic and timer capture, letting an ATTINY212 run a closed-loop boost with a dozen registers [Elektroda, excray, post #20673590] A proven design delivers 12-V output with 0.3 µs timing resolution at minimal parts count.
Why did the designer choose a ready-made 170 V converter instead of rolling his own?
The author is willing to supply PCB, schematic, code, and even remaining boards by arrangement; several DIY kits have already been sold [Elektroda, emil134679, post #21280047]
How much current does the clock draw?
Typical IN-1 digit needs 2–3 mA; with six digits multiplexed, average tube current is about 12–18 mA. The 170 V converter runs at ≈100 mW, so total USB-C draw stays under 300 mA at 5 V [NIXIE Current FAQ].
How can I detoxify cathodes to prevent poisoning?
Rotate digit patterns monthly or briefly display all numerals. This evens cathode usage and revives dim segments—proven effective over 14 years [Elektroda, madart, post #20672863]
Comments
Those lamps that make for colons, what markings do they have/where did you buy them? [Read more]
INS-1, where you get it, you buy it there, I used to buy tubes a long time ago. [Read more]
The project was successful, but since it will be in a wooden housing, compactness was probably not that important. Personally, I would choose a clock on vertical lamps, similar to this one, but with an... [Read more]
Such a pretty tile that it's a shame to hide it. :) How is the time set? Because it's the only inconvenience when we still have the summer/winter time change. DS3231 has a very small deviation.... [Read more]
That's right, you can make a transparent casing or (if the heat exchange allows) pour a transparent resin. [Read more]
No lamp replacement? The technical data indicate that the guaranteed lifetime for the IN-1 is only 1000 h. [Read more]
One has LC-516 link . I changed the tubes a few times so that the cathodes would detoxify and once two transistors died together with the CD4028 The advantage of the multiplex is that the lamps do... [Read more]
It was important because the housing is neither deep nor wide, more or less I see it as if you wrapped the presented circuit around, leaving the tube lenses outside the housing. The colleague above showed... [Read more]
My taste is probably due to the fact that I first had contact with displays on vertical lamps and I remained faithful to them. [Read more]
Do you have any experience with a high voltage converter controlled directly from the uC? At one time I wanted to make a simple PWM controlled one MOSFET transistor and a transformer from fluorescent... [Read more]
The new Atmel uCs are great for this. https://sm6vfz.wordpress.com/2020/12/11/boost-regulator-with-attiny/ In practice, it can be even simpler - ATTINY212: TCA0.SINGLE.PER = 4; // 30us period,... [Read more]
Great project (if there was a rating, of course there would be ⭐⭐⭐⭐⭐), I could do it myself. Is it possible for you to send the board design, diagram and code? [Read more]
@karoljuszkiewicz I don't look on the electrode too often but yes, a matter of agreement. I still have the boards as well as the code and the tutorial left because I already had a few customers for the... [Read more]
I love the compact design and how you integrated the Arduino and other components so seamlessly. It's got a cool retro vibe with those IN-1 + INS-1 tubes. I’ve been fascinated by NIXIE tubes for a while... [Read more]