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
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.

<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!
<p>hi! im a newbie on nixie clocks, some weeks ago, i bought an old 1971 Casio AS-L (with 12 nixie tube display) electronic calculators that still works from a thrift shop, since it is a calculator, it will be of seldom use, kinda plan to dismantle it, take the parts, and build a nixie clock, i just don't know if the calculator parts can be use for the clock, or leave it be and acquire new parts... this nixies, those projects i've seen on the internet are so beautiful.</p>
<p>Hi! Cool instructable :) </p><p>I'm starting to make it, but I'll dessign my own PBC with the size of my yet unexisting case and some other features I plan to add.</p><p>For starters I discarded the quartz cristal and your time function, I'm using a RTC module (DS3231) to tell me the time (it also can tell me the temperature!).</p><p>Oh, and I'm using IN-14 Nixie tubes.</p><p>I'll upload more photos as I progress.</p>
<p>I've added new code to prevent cathode poisoning, each hour at XX:59:55 all the numbers will start spinning for 5 seconds.<br>After some tweaking, I've finally got rid of that nasty ghosting effect adding a 0.2 ms blank state between intervals.<br>And I've programmed two buttons so I can change the time. ... I guess thats important in a clock :P</p>
actually your modifications are very useful, I was not able to implement a code like you did, but in my last clocks I added four pins to connect the future clock module :)<br>it would be nice if you will share your code with instructables community!
<p>I'm new to programming so I'm sure there are too many variables or stuff that's not as compact as it should be, but the code I wrote works as I intended and I'm happy with that :)</p><p>I'm in love with RGB leds so I had to put some of those in my clock</p><p>(they're located under the nixie bulbs). </p><p>Now, each hour of each day of the week the six leds will illuminate in different colors. </p><p>I'm adding a link to Github of my code: </p><p><a href="https://github.com/ruizgerman/ruizgerman-Nixie-Clock" rel="nofollow">https://github.com/ruizgerman/ruizgerman-Nixie-Clo...</a></p><p>The Schematic I'm using. Note that I'm using two separate modules as High Voltage PSU to turn 12V into 180V, and another one to turn those 12V into 5V.</p>
awesome! great job!
<p>I love the way this clock looks, I've had a similair idea for using Numitron tubes, with a simple dark stained case, and perhaps a dark-tinted glass front. I'm not completely sure how it'll turn out, but your case design is quite similar to what I was going for. Awesome looking clock, (I wish I could recreate it exactly), and great 'ible too!</p>
thanks! :)
OK andrea, I will start buying the necessary components ..is there a chance in the meanwhile to upload the improved PCD design? Mostly for phycological reasons :))
yup, go reading my last nixie clock instructable ;) and use that design
thank you andrea! take care my friend.<br>
<p>Hi guys! Great project Andrea! I would like to try it myself but cannot locate the BOTTOM side of the PCBs...? Do I need new glasses? :)))) I found the TOP side silk prints but not the bottom.. Any directions are greatly welcome!</p>
forget what I answered before l, it's the top view PDF ;)
:) its ok!, I think I found the bottom design on your other Nixie projects? Or is that not the correct one?<br><br>Basically I need the bottom side for the tube PCB and the main circuit... <br><br>Keep up the good work!<br><br>Salute from Greece :)
it should work, last version only has minor improvements, good luck!
step 2 - main pcb top silk pdf ;)
Really like this project and really well documented. Did you progress any of the improvements, in particular the rtc?
<p>Last week I managed to finish mine! :) I was trying to achieve something similar to your design because I loved it so much... Unfortunately I couldnt get a box that is even close to your beautiful rosewood box, so I needed to create it myself from an old solid wood block. This of course resulted a much less attractive outcome, but I still like the results. :) I also needed to add this dark brown color and apply an oil finish on the box. Instead of the screws at first I created the stands from small wood pieces, but finally I found it would look better to replace them to screws.</p><p>I used my existing controller board design for the electronics, but applied your panel design for the tubes' board and the same IN-4 tubes.</p><p>This is made for a birthday present and will be handed over tomorrow so keep your fingers crossed... :)</p><p>Thank you again for inspiring me to create this, I'm so happy that I could finally make it! :)</p>
woow that's awesome!<br>beautiful pictures too.<br>I'm happy you made it!
Thank you!!! :)
<p>This is the most beautiful nixie design I have ever seen, congratulations!<br>Awesome project description too, thank you very much for sharing! :)<br>I built a nixie clock successfully back in 2008, but your work actually inspired me to build a new one, as close to your design as possible. (I hope it's not copyrighted. :D)<br>I'm already done with the electronix, so I need to create a nice case from old/wheathered/reclaimed wood, which is going to be a challenge for me... :)<br>Keep up the good work!<br>Moire</p>
Awesome! I'm really happy you like it, I've been inspired by a nice project too.
<p>Very nice project.<br>Could you please share an estimate cost for the parts for this project?</p><p>Thanks</p>
<p>Hello, in the schematic I can not figure out what the &quot;neon dot&quot; connection is and where it connects to. Can anyone help me and also I'm using IN14 tubes but don't know what resister to use? The equation did not help at all.</p>
<p>neon dots are the two dots between hours minutes and seconds, but I didn't use them in my clock. Resistors are already in the schematic and b.o.m. if I remember right.</p>
<p>It would be interesting to see if you could add a PIR module so the clock only activates when there is movement in the room. I have built several Nixie clocks, but none of them have this feature. I have not built one with the IN-4 tubes as yet, so now I have a new project to work on. </p><p>Great looking clock and a very nice build description. I wish some of the others were as in depth as you are. Thanks again.</p>
<p>I already provided the pcb with &quot;connections to external sensors&quot;, and you can use them to connect the PIR module. Of course you have to update the software. It's one of my next projects.</p>
<p>Hi,</p><p>I would like to get a Nixie clock, I saw some on websites that you can buy, but in addition to be quite expensive for a clock, I'd like to make mine, just like I want it.</p><p>Do you think it is possible to build the whole, complete circuit on a matrix board (since I don't have the possibility to make industrial PCB's) ?</p>
<p>Hey there. I'm not sure if you could do it on a matrix board. You would have to be carefull with trace spacing etc, because a nixie clock will deal with some rather high voltages.</p><p>I'd recommend designing a PCB in something like KiCAD and then get it made by <a href="http://oshpark.com" rel="nofollow"> http://oshpark.com</a> It's a very cheap means of getting PCB's fabbed. It's a pooling service though, so it will take some time for the boards to be delievered to you, but for 5$/sqin (x3 because you order in multiples of 3 boards, so 5$ for 3 1sqin boards.) </p>
<p>I don't know, but you can try, just be very careful with high-voltage!</p>
<p>Very cool clock.</p><p>Maybe some one could help. I have already made a PCB and everything works, till the clock stops and won't continue counting. I cant reset with the reset button, but i can change the hours and minutes with the buttons.</p><p>Can somebody point me in the right direction? </p>
<p>hello Im having troubles transferring the toner to the copper plating on the PCB... is it the paper or is my iron too cold? its not adhering completely so im having a bit of trouble... and as for the 74141N I have a PD74141P? I think.... will that be ok? plus I have the American Burroughs (I think B4032 the letters are erased and im reading off of marks etched in the glass) will that work in substitution for the IN-4's ??? <br>all in all very nice build!! you have successfully converted me from a tube amp builder to a nixie tube clock builder... <br>Cheers from Korea!!! (eeuuuhhh South Korea If you were wondering :P)</p>
<p>btw the voltages are similar (170V for the Burroughs B5031?) with 1.5 ma peak cathode current and a series resistor (according to the data sheet) of 15K ohms for 170V, 91Kohms for 250V and 200Kohms for 300V</p>
Awesome! I really want to build one!<br><br>Where do you get the 16khz crystal though?
<p>try on eBay or in an electronic components shop</p>
Ive looked in those places. I can find plenty pf 16mhz crystals, but no 16 khz
yes M16.000 is 16mhz, not kHz, if i wrote 16khz i made a mistake!
Ok, that makes more sense. It is listed in your BOR as 16000 Hz. <br><br>Thanks again for taking the time to share your outstanding skill with us!
Do you have any part # or specific identifier to the ones you have purchased? M16000 is coming up with nothing.
it's the crystal for Arduino, it's 16Mhz
<p>Awesome Project, astounding skill! I would like to build one myself. I have a question though...would i be able to substitute the IN-4's with IN-14's without adjusting the construction. Sorry if this is a silly question, I make noob's look like rocket scientists... it seems that you have left huge margins in terms of customizing! </p><p>Once again, Brilliant!</p>
<p>you can connect tubes with wires, instead of making a new tube-shield, good luck!</p>
<p>Would i have to change the circuitry to use IN-14 rather than IN-4? I <br>also looked at the dimensions of the PCBs and the length by width did <br>not match up at all.</p>
<p>you have to change tube shield and probably some resistors..</p>
<p>Andrea, <br>thank you so much for this Instructable! I finally managed to complete this <br>project. It took me so long because I made a few changes in way of making this <br>circuit. First of all, I used photoresist method instead of toner transfer. I <br>would say, that method is the way easier, than method that suggested, even I <br>am, total newbie, succeed in it at first time. I included a few photos that you <br>could see the final product of this method. (By the way, I am really sorry that <br>you&rsquo;ve seen my first attempt, I&rsquo;ve learned a lot :) ) I consider about writing my first <br>instructable exactly about this method.</p><p>Next thing <br>that made me to slow down are pin holders. In my hometown I couldn&rsquo;t find any <br>of them, so I had to make them by myself with copper wire. Well, they are not <br>as straight as these that you used, but it does its job just fine.</p><p>The last <br>thing is a code. I knew that I&rsquo;m going to stuck with for too long. Firstly, I <br>tried to program it with LPT programmer, but I got no luck in it. I tried a lot <br>of times to program it, I tried tons of software, but only thing that worked is <br>Arduino, that I bought recently.</p><p>I would like to say &ldquo;thank you&rdquo; again, Andrea. Photos <br>of your clock have inspired me to make it. Every time that I was looking at clock <br>that you&rsquo;ve made, I felt like I was so close and so far away from success at <br>the same time. Something was burning in my chest, after one little sight at <br>this masterpiece, something as neon in these indicators, so it made me keep <br>going, even after so many technical problems, that I got in process.</p><p>P.S. I am terribly for the mess on my desk.</p>
<p>Hi Emil,</p><p>great work! I know how you can feel, I had the same feeling when I saw Max Pierson's <a href="http://www.maxwellrosspierson.com/2010/10/13/my-nixie-clock-build/" rel="nofollow" style="">beautiful creation</a> some years ago, and I begun studying electronics and buying nixies! :^)</p><p>This is great satisfaction!</p>

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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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