Picture of simple user-adjustable DIY Nixie Clock

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!

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vodkapom3 months ago


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.

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) ?

andrea biffi (author)  vodkapom4 days ago

I don't know, but you can try, just be very careful with high-voltage!

Garagebrand2 months ago

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!

Once again, Brilliant!

andrea biffi (author)  Garagebrand4 days ago

you can connect tubes with wires, instead of making a new tube-shield, good luck!

sinaarian8 days ago

Would i have to change the circuitry to use IN-14 rather than IN-4? I
also looked at the dimensions of the PCBs and the length by width did
not match up at all.

andrea biffi (author)  sinaarian4 days ago

you have to change tube shield and probably some resistors..

emil.godjaev made it!6 days ago

thank you so much for this Instructable! I finally managed to complete this
project. It took me so long because I made a few changes in way of making this
circuit. First of all, I used photoresist method instead of toner transfer. I
would say, that method is the way easier, than method that suggested, even I
am, total newbie, succeed in it at first time. I included a few photos that you
could see the final product of this method. (By the way, I am really sorry that
you’ve seen my first attempt, I’ve learned a lot :) ) I consider about writing my first
instructable exactly about this method.

Next thing
that made me to slow down are pin holders. In my hometown I couldn’t find any
of them, so I had to make them by myself with copper wire. Well, they are not
as straight as these that you used, but it does its job just fine.

The last
thing is a code. I knew that I’m going to stuck with for too long. Firstly, I
tried to program it with LPT programmer, but I got no luck in it. I tried a lot
of times to program it, I tried tons of software, but only thing that worked is
Arduino, that I bought recently.

I would like to say “thank you” again, Andrea. Photos
of your clock have inspired me to make it. Every time that I was looking at clock
that you’ve made, I felt like I was so close and so far away from success at
the same time. Something was burning in my chest, after one little sight at
this masterpiece, something as neon in these indicators, so it made me keep
going, even after so many technical problems, that I got in process.

P.S. I am terribly for the mess on my desk.

andrea biffi (author)  emil.godjaev4 days ago

Hi Emil,

great work! I know how you can feel, I had the same feeling when I saw Max Pierson's beautiful creation some years ago, and I begun studying electronics and buying nixies! :^)

This is great satisfaction!

sinaarian8 days ago

Do i have to put a 10K resister anywhere there is a 15K or 4.7K (or 3.3K)? I am not sure what this means "Please note that where you read 15K resistors you have to interpret 10K
on the main circuit plus 4.7K (or 3.3K) on the shield pcb." .Could someone explain?

andrea biffi (author)  sinaarian6 days ago

Since schematic is actually splitted in two different pcbs, I decided you can use a fixed value resistor (10K) on the main PCB, and a second resistor on the tube shield, wich can vary related to the type of tubes you use. The sum of both values has to respect formulas you find in Threeneuron's great explanation.

Read also my explanation on step 2. I hope everything is clear now...

jgluch4 months ago

Great writeup! I'm looking into making a clock and trying to start sourcing components. I was just wondering what the dimensions are on your PCBs. I think I'd like to try the photoresist method as this is my first time etching a PCB. Any other advice you have would be great. Thanks!

andrea biffi (author)  jgluch4 months ago

photoresist would probably work, but this is a very difficult pcb as first try..

you can read dimensions in step2 images. Good luck!

good instructable, Thanks. . . .Im planning on working on it If i got my money now. . . .

jgluch4 months ago

If it's possible could you send me your Diptrace files? I would like to use the same components but I need to make the board slightly smaller. That would be great. Thanks!

lawrence.loblevyt made it!5 months ago

Hey! Been meaning to have a go at one of these for a while, and have been doing my homework with a bit of help from your Instructables page. Honestly, its a fantastic design, simple yet functional, I like the way you have done away with the multiple drivers, even if it sacrifices a small amount of brightness.

Managed to get your schematic working as a base, and plan to add in either some diodes to combat the slight ghosting issues or some extra transistors to completely shut the signal off between the multiplexing signals. That and I will add in a modifiable relay circuit to attach a motion sensor to, or a simple button to display the time for a pre-determined time.

One issue i'm running into before i do that however is that the time every now and again resets itself to default with no interruption in the display. I've been puzzling over this all week and have narrowed it down to what i can think are the two issues, either the crystal oscillator has the wrong load capacitance (i'm using 16pF for the moment until the 22pF ones come through) although this doesn't seem to be likely. The other might be the N channel mosfet, as when i touch the rearmost plate, it naturally conducts but interferes with the atmega, making the display flicker and then freezing it.

I was wondering whether you ran into these issues, or if you might have an idea on what was going on?

andrea biffi (author)  lawrence.loblevyt5 months ago

looks great!

nope, I never had your issues, but it would probably fix when you put everything on a pcb and solder the components. The Atmega circuit part is a good old verified schematic, it should work well.

If you wish to add an external sensor or a pushbutton, my pcb design already provide connections for it, just on the edge near the atmega.

In my pcb I already managed to solve any ghosting problem, with no interruptions in the signal between multiplexing since there is no time to insert that with only one single driver, and now it works perfect! My next nixie clock is on the way!


I took your advice and stuck it all to the PCB. However have run into some problems again. The clock cycles fine, but only displays the digits 0 and 4 with all other blank, I've checked and there is a voltage across the 10 pins so i don't know what would be the cause of this. I suspect a burnt transistor from the soldering maybe?

andrea biffi (author)  lawrence.loblevyt4 months ago

ouch that's probably discouraging. I know that my pcb design is very compact and has very thin traces, so it's very difficult to make "at home".

usually a transistor doesn't burn for the soldering...I suggest you to look for short-circuits between adjacent traces, and also check for interrupted ones.

I went through and checked all of the traces for continuity, and to see if there where any branches. Also got the oscilloscope up and running and was able to see that the signal through the transistors was working perfectly, this leaves two options, the driver is faulty (i replaced it with another so i'm certain its not that) or the at mega has been fried. I've gone with the latter, so ordered a new one.

Running the oscilloscope was really cool and made possible to see the multiplexing signals clearly! I'll try and get a picture tomorrow to show you if your interested? Wish me luck with the new atmega!

And thanks for all the feedback, it's really refreshing to see someone with so much enthusiasm for his projects. I look forwards to seeing what new tricks you can cook up! Makes me wish i had chosen electrical engineering over mechanical.

andrea biffi (author)  lawrence.loblevyt4 months ago

It seems that changing Atmega will solve the issue.

When I saw nixie clocks I wished so much make one of those that it took two years of documenting (I'm a civil engineer, never studied electronics or IT before) to assimilate the necessary skills and design my own circuit. I also made more than 12 different versions of the pcb to reach that final one.

I'll also try replacing the atmega with a fresh one, there is a chance I've shorted it meaning the digital pin outs are not firing. I tried replacing it with another atmega which had this problem and it displays digits 0,1,4 and 5 instead of just 0 and 4. I'll report back if this solves it. I'l try to get it on an oscilloscope as well, just to be sure.

richb775 months ago

What a great looking clock! I just wish i could program enough (anything!) to add an alarm function and night dimmer/power save.

BRILLIANT work here. Love it!

andrea biffi (author)  richb775 months ago

I would like too... maybe I will be able soon to update the code with those features.

longpcb5 months ago


I want to diy for me one nixie clock the same this project, but i don't know how to convert code file you posted to file .hex! So, can you help me, convert the code fife of this project to file .hex and send to me please? Thank you very much!

My email:

andrea biffi (author)  longpcb5 months ago

I'm sorry I'm not very skilled in programming, not yet ;-)

I'm used to upload the code with arduino, then place the IC on my pcb. Good luck, please post the method when you'll find it, that will be useful!

So, You used file.ino or file.hex for programming Microchip ATMega168?
andrea biffi (author)  longpcb5 months ago

just connect your Arduino to your pc via USB and program the Atmega168 in that way, then remove it from Arduino and place it on the pcb socket, you don't need the ino or hex file, Arduino software will create it for you and upload to Atmega. My code is attached to step 4, you can also modify it.

EdwinasD7 months ago

hi. i have a question. i see that there is neon dot connection, but i dont understant how it works. will it blink every second?
p.s. sorry for bad English.

andrea biffi (author)  EdwinasD7 months ago

yes, since the pcb is widely ready for further upgrades, I added the possibility to connect two neon dots between the three digits groups. The dot's will not blink, it would be annoying in the night IMHO...

akirk1110 months ago

Andrea, GREAT writeup! I'm planning on building this on a breadboard rather than a pcb. I just wanted to clarify a few things before I start ordering parts. I'm going to run it on 9V input only, so I can do away with C9, C10, D3, the 12-35V/9V selector switch, and the L7809? I'm not seeing on the schematic where to pipe in the 9V battery for a backup. Pin 1 on the ATMEGA, listed as PC6_(RESET, has a reset lead coming off of it in the second schematic, but doesn't go anywhere on the first. On the first schematic, pin 12 coming off of the 74141N driver shows it goes to "CND" before ground. I'm still a noob to this, so what the heck is "CND"? Do you also have the updated schematic to use the third position of the on/off/on switch to use as a sleep mode? Thanks in advance!

andrea biffi (author)  akirk119 months ago

Hi! Actually I don't suggest you to make the circuit on a breadboard, remember you have to do with high voltage, so it's very dangerous, you don't want a wire to disconnect and touch your nose when you are looking the beautiful nixie glow closely!

The battery will work good, but you have to implement a code with an automatic sleep function. Anyway, if you look my second nixie clock ( you will find the updated schematic with 3rd position as sleeping mode, and also you will find a new pcb ready for battery connections. When you connect battery the power-socket disconnects the wall-plug line.

Good luck!

I'm not terribly worried about the electricity. I've been zapped with mains power, 100,000v high power ignition coils, and others I care not to mention. I like the way breadboards look when I put them together. I found your other schematic after I had submitted my first comment. I'll be using that one to build mine. Looking forward to seeing more code implementation that you alluded to in another comment.

andrea biffi (author)  akirk117 months ago

just remember the "hand in the pocket" rule when you touch the hv circuit.

I'm sorry that I have no time to implement a new code for now... I hope that someone here on instructables can work on that.

Nighter3D akirk119 months ago

Hello. i may not be the author, but i can answer your questions ^^

The L7809 block only serves to regulate excess voltage from a big supply to a suitable 9v. if you are using a 9V supply you can safely omit it except for C10 which serves to clean the power a bit...which you probably want.

Regarding the 9v Battery. it can be attached to just the 9V line. Although a slight warning is that the 9v will be depleted in record speed as the project does not seem to be capable of intelligently turn of the Nixie without a external power-source and 9v batteries are not designed to give the kind of power the nixie needs...atleast not for long.

I think you are misreading CND for GND (ground). the reason its double is cause one is a Symbol (which connects to all others symbols on a schematic) and the other is a pin.The reset goes to one of the 2 switches in the upper-right of the schematic with the driver and power-supply. Remember if you click on a image on instructable you will get a better view...if its bigger then the browser can show you can click on it again to download a full-resolution picture! ^^

akirk11 Nighter3D9 months ago

I thought C10 might serve a cleaning function. As far as the "CND" I was looking at the high res. Still wasn't quite high enough to make it out. I figured it was a ground, but I'm still pretty green at making electrical components. Thank you for the clarification.

emil.godjaev8 months ago

Thank you very much for this instruction. I already had started soldering and noticed few missing parts. First of all its diod D5. B.O.M. doesn't have it. Then, your logo is hiding a number of resistor. I just can't read it. Could you help me? Also I wanted to ask you a bit silly question: may I change capsitor C1 1uf 350V to 1uf 400V. Here, in my city, i just can't find for 350V.

Then is it important to resistors R17 and R18 to have 1% accuracy?

I got question about programming ATmega8. May I use LPT programmator and PonyProg programm for this?

For now thats all what I wanted to know. I hope you could reply me as soon as possible. Thank you again.

andrea biffi (author)  emil.godjaev8 months ago

I hope you can find more info in my other instructable here

yes you probably can change the capacitor, and accuracy of resistors is not so important, I don't know PonyProg I'm sorry

Nighter3D9 months ago

Ah i love nixie clocks. Working on a couple of tube clocks myself. Kinda doing a "1 of each". Got a working Nixie prototype (Direct driven through multiple drives and a few shift-registers), Made a design for a tiny Numitron clock (They are the most beginner friendly. writing a instructable on them) and am already expecting some VFD tubes (again to be given a instructable as i work on it. Seem to be very few off)

May i make a suggestion though?

Look up the MC34063. Its a very popular "jellybean" Switching power-regulator often used to design high-efficiency step-up/down power-supplies (also very popular for Nixie supplies!). the only issue i have with your design is namely the Linear regulator used to convert power to 9v. if planning to convert a large voltage like 35v to such a low power that is going to power tubes its kinda innefficient...scratch that HORRIBLY INEFFICIENT (25-30%). Its a shame to have made a highly efficient Nixie switching supply, but to have it fed by a linear supply that is horrible inefficient... also makes for ways to make your own efficient energy-boosters/converters. Heck you can even invert power for Vacuum tubes or make a VFD power-supply.

Personally i avoid the IN-4. The IN-4 and IN-1 are quite known for lacking the Mercury within its gas mixture that most other tubes have. this shortens the life a bit compared to some other Nixies i have around. IN-1 is know to live for months at most and the IN-4 is know to last a year or so. You can see if mercury is present due to a blue hue within the Nixie glow.

andrea biffi (author)  Nighter3D9 months ago

yes, particularly the IN-1 has a very short life, but if you implement a good code to make the clock turn on only when you need it, it will last for 100 years, I'm working on it.

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