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As first instructable of the year I managed to finally complete my age-long nixie clock project.
Nixies are neon valve tubes, where ten cathodes have shape of digits and are lighted up by plasma when high voltage flows through them. I love these old era displays, which have been employed in last century before I was born.
In last year I've been slowly collecting components and knowledge to build some nixie clocks as Max Pierson's beautiful creation, I like the old style, the roundness of glass tubes, the rough wood case, the simplicity of the design. That clock has definitely inspired my project. Even though I really love vertical digits arrangement I keep that original feature for my next clock.
 

Therefore this first born is a six digits horizontal wood desk clock, with six big round Russian IN-4 nixie tubes, no dots, no visible buttons, no LED illumination, only a big massive rosewood block and the power of plasma ;-)
I have to explain you what the title means:

simple because it can be entirely built with common tools and from common components, you only have to order six IN-4 nixies and one nixie driver

user-adjustable because it's predisposed for many external sensors and additional features (as neon dots between digits, alarm, etc.)

DIY since you neither have to buy external shields or to pay for pcb manufacturing, just follow my instructable ;-)


WARNING: this circuit raises the voltage to deadly 300V so you must avoid to touch contacts while working, I'm not kidding, please BE CAREFUL!

Step 1: The schematic and working principle

Lately, after some research and a fast designing, I attained this functional high voltage power source circuit. Since there is a full step to step guide about the hv power source section of my clock, I will pass over that explanation. There is only something to say about the input voltage for the clock: to increase the universality of the project I decided to give the possibility to power the clock with a voltage from 9 to 35V. The best solution (in terms of efficiency and thermal dissipation) is to connect a 9V DC PSU (500 mA or more), but if you want to power the device with a voltage from 12 to 35V you only have to shift the voltage switch in direction of the ON-OFF switch (which has a center ON position between two OFF ones).
With the pot you have to set the voltage (read next step for high voltage pins) to the about 190V needed to power the IN-4 nixies (in multiplexing displays is better to use a bit more than the 180V needed to light a single nixie tube). You can of course set up the proper voltage for any other nixie tube.
 

The other section is the logic circuit, where a cheap Atmega8 IC (but you can also use an Atmega168 or Atmega 328), through a nixie driver and some high voltage transistors, controls the digits.
The nixie driver is a K155ID1 which is the Russian equivalent of the 74141N, and it spares you to use 20 more high voltage transistors. This driver is not very expensive, but it's not longer manufactured, so with time it will be more difficult to find, for this reason I wanted to use only one in my project (while there are many nixie clock projects which uses one driver for each digit).
This has been possible thanks to some references I found in the web
(maxwellrosspierson.comelbastl.sweb.cz,
mlknaweb.blogspot.itglowbug.nl,
neon1.net, threeneurons.wordpress.com)
but mainly thanks to Jeremy Howa and Brad Lewis for their Arduinix project, which enlightened me about multiplexing power and from where I took the original code.

My schematic is drawn in Diptrace, a simple pcb design software, I divided it into two pats so to show it better, read notes on the image to understand circuit parts.

I don't understand howthe 74141 works. Isn't 4 input 9 output meaning 1 per nixie clock? On many other nixie project people use 6 drivers.. Can you explain?
<p>from what i understand:</p><p>with 6 drivers:</p><p>all anodes are connected to power and each driver connects specified cathode for a number you need lit on a lamp.</p><p>with 1 driver:</p><p>corresponding cathodes in all lamps are connected to each other, so all 1s to other 1s, 2s with 2s etc. </p><p>groups of cathodes are connected to driver.</p><p>anodes are connected to power with transistors and they are connected toother driver like arduino or something.</p><p>that setting can work like a simple matrix, for example you connect cathodes number 1 by their driver and chose which anode is connected in that moment so the number 1 is lit on corresponding lamp. with all anodes connected at the same time, lamps would display the same number, the one you'd choose with driver connected to cathodes. </p><p>when you want to light different numbers on each lamp, for example you want 4 lamps to display 2 3 5 7 you have to switch on anode 1 and cathode 2, turn off, set anode 2 and cathode 3, turn off, anode 3 with cathode 5 and so on. they would have to be lit on and off very fast so the eye would not notice the flickering of lights.</p><p>it's a bit more complicated way but with this you can use less components</p>
I bought like 24 of them on ebay for my nixie tube Clock, Indeed this is a bit more complicated but at the same time it is very smart on your end to thought about that!<br><br>Thanks for the info, but I will stick with my simple model 1 Driver / tube ;)
<p>That's a great instructable! Thank you so much for sharing the nice tutorial! </p><p>I really like the box, nice case for the circuit! :)</p><p>I also found a nice <a href="https://easyeda.com/zhelezny.andrey/___12-rtnFWQ8qk" rel="nofollow">Arduino Nixie Tube Clock project</a> on EasyEDA open source community. I hope I can make my own Nixie Clock.</p>
<p>is there any chance to get your diptrace files for this project? i finally managed to get the power supply to work after few approaches and making the clock is the next step</p>
<p>This is nice! I'm on a shoestring budget, though, so I can only afford <em>four</em> IN-14 tubes. What changes should I make to your design for the adaptation?</p>
<p>Hi! No changes! Just don't connect the two digits for seconds.. And you also can save some transistor... but leave space so you can add seconds later!</p>
<p>I've built two of these now, using your circuit design and modified code by ruizgerman, worked back to fit your schematic.</p><p>Used IN-18 tubes, and running from a 9v power supply.</p><p>I did discover that a 12v power supply will cause a massive heat problem, you would need a substantial heatsink on the voltage regulators to use a 12-35v supply, and the higher the supply voltage the worse it gets. I would STRONGLY recommend using a maximum 9vDC supply voltage.</p><p>I am currently working on my own schematic based on yours, eliminating a few things I don't need like the sensor inputs and the voltage regulators - I will be using a self-contained AC-DC transformer to do most of the work, and allow me to have a direct mains supply without a huge power block.</p><p>The purple one was built for a friend, the wooden based one is my own one, the last digit is awaiting a replacement from the ebay seller as the tube was DOA. The silver cased clock was a kit I was given last July as a birthday gift and got me hooked on nixies in the first place.</p><p>The one i am planning will hopefully make use of a self contained switchmode supply similar to http://uk.rs-online.com/web/p/switch-mode-power-supply-smps-transformers/7924379/</p>
heating problem will be probably due to a mistake in making PCB, since I can power my nixies also with 24V or more with no heating. <br>anyway it's good you simplify my circuit and use only the 9V supply, with no sensors input, that will be smaller and simpler to built. <br>I'm very glad you too love nixies and you could make your own clocks, I know that's very satisfactory! have a nice holiday :)
<p>Yeah, I'm not sure what's causing the heat issue. The 9v supply connects through the same regulators (I didn't bother with changing the connection from 12-35 to 9v when I put the new power supply in), and the heating issue drops away. Exact same circuit, but 3 volts lower and there are no temperature problems whatsoever. This is common to the two completed clocks and the test board I built, 9v is fine but more than that and significant heating issues appear. Dropping 3v through the regulator shouldn't cause it, and the 5v regulator, which rally has more work to do, doesn't suffer the same issue dropping the 4v it has to handle so it's a bit odd.</p><p>Hopefully when I complete my design I can figure it out a bit more clearly, I'd honestly prefer a switch-mode supply for efficiency anyway.</p>
IN-18 are AWESOME!
<p>For Andrea Biffi:</p><p>Could you help me to find a solution for:</p><p>Add neon bulbs between hours/minutes and between minutes/seconds with will blink with a delay of 1 second?</p><p>Add under every Nixie a RGB LED.</p><p>Thank you very much.</p>
search on internet, there are some projects like this you're looking for!
<p>Super helpful post! I've been looking through everything trying to understand it all and comparing your circuit to Threenueuron's. You use a 74141N to drive the Nixies while he uses individual HV transistors. Will you code work for his style of circuit as long as its connected to the same pins on in ATmega? Thanks!</p>
<p>Hi, This looks great and I would love to try it to add to my collection of a PVelectronics nixie clock and my Nixie thermometer I have built... I have a question if I may tho... Do I have to program and mount the AT chip or can i just mount my arduino to the board and have the K155ID1 and anode pins connected to the arduino pins?</p><p>I did this on my thermometer I built and leached the 12V power from the input of the arduino to also power the 170V driver for the tubes.</p><p>I know this is probably a stupid question but I am not sure if 'pin2,3,4,etc' in the code for the arduino corresponds to the same pins on the chip.</p><p>Thanks, Craig.</p>
<p>Hey Andrea, this is a very nice tutorial, and a very nice clock indeed! I've already ordered 6 IN-4 tubes to start building. :)<br>One thing i don't understand is, why do we need an additional HV board, when all the components of that HV board are present on the main board?</p>
Indeed, you don't :-)
<p>Hallo, followed your steps, but I got an issue, code is running reset button resetting, but it doesn't generates 180 V, I can see only 7.8 volts. Honestly I don't get where is a problem. Can you give me please some advice.</p>
I have the same problem. It only shows about 8 volts. Have you found a fix for the probslm?
<p>How did you solved this issue?</p>
<p>I solved it by making a new high voltage board and connecting it to the existing one. The schematic is the same as this one and it works, here's a link:</p><p><a href="https://www.instructables.com/id/High-Voltage-Power-Supply-for-Nixie-and-Valve-Tube/" rel="nofollow">https://www.instructables.com/id/High-Voltage-Power...</a></p><p>As far as what the problem in the original one is, I have no idea but i suspect it might be a non working element, although I couldn't detect which one.</p>
<p>But if I have already done this PCB, how can I connect the high voltage board that you used to the main board?</p>
<p>Sorry I can't upload an image of my board because I put it in a case and it will be a pain in the *** to take it out. I will try to show you on the board template:</p><p>The red line is the high voltage. You have to connect the HV output to it (the easiest way is just to connect it to the +180 V test pin)</p><p>you will also need to connect the HV board to GND and +9V VCC, but that should be easy.</p><p>Hope I've helped you :)</p>
<p>The high voltage supply works perfectly, thank you very much!</p><p>Last question: which code and tubes did you used? Did you included RTC module?</p><p>Thank you again Svetko</p>
I've used IN-12 nixies and the code is the one written by the author of this innstructable.<br>It doesn't have RTC function. <br>I have tried using a code by another user - ruizgerman ( you can find it in the comments below) which has a RTC and anti ghosting program, but it did not work for me.<br>Another thing you should be aware of is that you have to use an Arduino to flash the microcontroller. I tried using an AVR programmer but it didn't work, the fuse bits and oscillator frequencies were all messed up. I think it might be possible, but I don't know enough about these things.
<p>Thank you very much Svetko, I will try this solution in the next days!</p>
<p>hello!</p><p>nice clock </p><p>i am planning to build one with IN-8 tube </p><p>do this code contain anti-cathode poisoning ? like random number for every 5 seconds</p>
no, it doesn't, I had no time to improve the code lately
<p>Hello!</p><p>It's done. I can push that &quot;I Made It&quot; button.</p><p>This is my version of your nixie clock, it's not as fancy as yours, but that was never my intention, so I'm very happy with it.</p><p>Custom pcb, custom case, programmed it myself ( with your code as base).</p><p>In the video you can see its anti-cathode poisoning routine and the leds are like pew pew pew.</p><p>I've made the leds to change color randomly each hour.</p><p>Last summer I didn't know how to design a pcb, or even how to program a uC, so you can bet I'm proud of what I made :)</p><p><iframe allowfullscreen="" frameborder="0" height="281" src="//www.youtube.com/embed/f01A36BqwSw" width="500"></iframe></p>
<p>Hello,</p><p>I have a question for you: did you used the same tubes shield of this instructable of did you found/made it? I love the LEDs under the Nixies and I'll be glad if you will answer me.</p>
<p>I made the shield myself using Eagle CAD.</p><p>The bad news is that my laptop died and I lost the Eagle file.<br>The good-ish news is that I uploaded a screenshot of the diagrams here on the comments, so it can be recreated.</p><p>To save space I made to shields, one on top of the other, the main electronics on the bottom, the nixies connections, leds and resistors on top, and some cables...</p>
<p>Thank you very much ruizgerman, beatiful clock ;)</p>
can you please help us with anti-cathode-poisoning program? would you like to share your code? thanks!
<p>I've already done it in a previous comment, but here it is anyway:</p><p><a href="https://github.com/ruizgerman/ruizgerman-Nixie-Clock" rel="nofollow">https://github.com/ruizgerman/ruizgerman-Nixie-Clo...</a></p><p>And as I also said, the code is written in a &quot;non-professional&quot; way, so it's not the most efficent code I could come up with, but hey, it works ;) </p>
thanks again and sorry for I didn't realize it's you! good work!
woow! that's really beautiful! I love the rgb effect!
<p>Hello! awesome instructable! Only I ran into a small problem with the tube pcb. The PCB files for the tubes that you made do not fit the in-4 tubes that I purchased. The pictures of the etched tube boards that you made have the right holes, however the actual files that you provided are different from the etched ones that are pictured. Could you email me the files for the boards that are pictured in step 8?? </p>
probably you are not printing them with 100% zoom... try to check it
The boards that you have etched in the pictures have the right holes. However, the files that you shared have different holes.
look te PDF files I uploaded in the third Nixie clock, they're the last ones and better ones
<p>I checked in the third clock and the holes still do not match the holes for the IN-4 nixie tubes that I bought.</p>
that's really strange... PDF files are right, and in-4 nixies are all with same pin geometry...
<p>Hmmmm... thats weird. Maybe I just bought a weird type of IN-4. Because on mine all the pins are evenly spaced with 1 space where the two pins are more spread out forming a gap. In the board that you used however it has 3 spaces where the pins are more spread out. If you look at the image below you can see that gap. </p>
<p>I looked at the pins and the board and now I realized that the gaps in the pcb correspond with the pins that are not used on the nixie tube. </p>
<p>Can someone point me to Bounce.h, event.h and stream.h.<br><br>I cant find them in my standard libraries or in the downloads :(</p>
<p>hai</p><p>** depends whether you wish to build electronics or code computers .</p><p>** those many years ago when my ill-spent youth constructing electronics and studying instead of chasing girls </p><p>Nixie tubes IN-14 - 7441 - driver - preceeded 74141 , with the MAINS frequency (50 Hz as the clock ) . This is surpisingly accurate as loading shifts the mains frequency so generator plants increase rotation frequency when no load so that 08;00 its the exact frequency day to day . Saves electronics </p><p>At the time the 7492 was available ( divide by 2 and 6 ) . Thus a simple matter </p><p>Add in a few resets to sets , thus as preceeded the glut of dig ital clocks which then added radios - added my own detector circuit - code set to turn on and thus the code out hour later . As stated ill-spent youth - wisdom of age - and cynicism - chasing the young ladies - would have been better uise of the time </p>
<p>Hi andrea,<br>I'm doing a similar project using this instructable as a template, and I have a question about the arduino code.<br>I noticed that you are using the function millis() as a reference for the current time. However, after doing some research, I found that the value returned by this function overflows and resets to zero approximately every 50 days. Does your code account for this and is the performance of the clock affected by it? <br>Thanks a lot!<br></p>
actually the best solution is to use a real time clock module, but I still didn't improve my code to use it...
<p>Not necessarily, all you need to do is <br>count the overflows, and then add the maximum value to your time <br>variable. Here's an example of what I'm talking about:</p><p>int overflowCount = 0;<br><br>unsigned long millisMax = 0b11111111111111111111111111111111;<br><br>unsigned long prevTime = 0;</p><p><br>void loop()</p><p>unsigned long runTime = millis();<br><br> if(runTime &lt; prevTime)<br> {<br> overflowCount++; //count the overflows in millis()<br> }<br> prevTime = millis();<br><br> unsigned long time = (runTime/1000) + ((millisMax*overflowCount)/1000); </p><p>With<br> this modification, the code should be unaffected for at least 50,000 <br>days, or 137 years. No need to spend extra money on an RTC module or <br>modify the PCB :)</p>
thanks! that's so useful!

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Bio: I'm an Italian freelance structural engineer, graphic designer and photographer. I'm also investigating electronics, robotics and science in general. I enjoy hacking and ... More »
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