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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.

<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="http://www.instructables.com/id/High-Voltage-Power-Supply-for-Nixie-and-Valve-Tube/" rel="nofollow">http://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>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>
<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!
<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>

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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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