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IV-11 VFD Tube Clock First Design

IV-11 VFD tube Clock March 2012 Wooden case


New case design New case designNew case design

This is a project i designed a year ago but never built, because of not enough spare time. This month i found some free time so i started building it and i send the pcb layout for manufacturing. 

All started when i received some IV-11 vfd tubes from an ebay seller i ordered from and i started testing and prototyping by first trying to simple light up the VFD tube.

A VFD tube works like a 7-segment led display with some small differences.

A) The Filaments. The Filaments exists to power the tube. We have to supply these two pins with 1.2Volt and nothing more (polarity doesn't matter).  

B) The Grid. The Grid is like the common anode of a 7-Segment LED display. So the Grid has to be pushed high at 60Volt (in these tubes) in order the segments to be able to light up.

C) The Segments. The Segments light's up simple by pushing them high at 60Volt.

Here are the very first steps of powering the tube manually.

IV-12 tube Testing

To make the powering of the tube digitaly in order to use it in the final design we have to built a simple circuit which will impliment the above description. The circuit has to be able to push each segment at 60Volt or Pull it to Ground at 0Volt. To do this two transistors (Push-Pull) are needed for each segment. One for pushing the voltage and one for pulling it down.

Push Pull Transistor connection:

We have 9 lines at each tube which need push pull transistors including Dot segment and Grid. So we have 2 transistors x 9 lines= 18 transistors in total for one tube, 28 for 6 tubes (8 lines for segments are in common for all tubes, only Grid is seperate and used for multiplexing). The number of transistors needed are enough for a fault on soldering or pcb etching (more routes) decreasing the finall product reliability and increasing cost because of the more pcb space needed. Less components more reliability.

To make VFD tube driving easier and more reliable Maxim has built MAX6921. MAX6921 is a Push Pull shift register where each bit of the register is ported on a specific pin of the device. So if we shift a bit of '1' the corresponding pin will be pushed high and if we shift '0' the corresponding pin will be pulled low. The communication to the shift register is implimented via SPI which makes it more easier as most of the MCU's nowadays have embedded SPI. By using this chip we only need 3 pins from the main MCU to impliment the SPI communication and nothing more. 

Prototyping the basic powering circuit using MAX6921 VFD tube driver.

VFD-Tube clock bread board testing   

To make all the 6 display tubes used in clock, appear at the same time we have to multiplex them. To do it so we have to turn on and off each tube in the row, enough times in a second in order, the transaction not to be visible in human eye (about 70~100Hz). As you can see on the above right video multiplexing for two tubes is tested.

Testing Filaments in series.

Testing MC34063 PSU

Describing the final circuit. 

The integrated circuits i have used are:

The main brain and RTC, ATMEL's AVR Atmega168p which has SPI, 16K of memory to write plenty of code, Counter/Timer with asychronous external crystal interrupt to update the RTC even in sleep mode, ADC for ambient light sense, an Analog Comperator for voltage drop sense to turn mcu in sleep mode when runing on backup battery and PWM to control LED brightness and voltage booster for Segments brightness. 

The MAX6921 VFD-tube Push-Pull driver used for the tubes driving.

The external supply voltage of the circuit is designed to be 1A 12Volt Power Plug Adapter.

To power the two chips a simple 5V stabilized power supply with LM7805 is used. Also has been used a full bridge rectifier in order to make the circuit work in any voltage polarity. At the output a low voltage drop 1N5817 diode is used to prevent back voltages.

To convert supply voltage from 12Volt to 60Volt for Grid and Segment supply a boost converted has been used which is controlled with PWM from Atmega168. The boost converter is inspired from adafruit's ice tube clock. A pull down resistor has been used at the MOSFET Gate to pull it down in no operation and a 60Volt zener diode is added in parallel to output to prevent over voltages.

A backup battery is used to keep runing the mcu when power supply is unplagged. A low voltage drop diode 1N5817 is connected in series to prevent battery charging.

Three buttons are used for user interface (configure time/date/alarm and change menu) with pull up resistors and decoupling capacitors for spikes, AVR In System Programmer, and a voltage divider used for voltage drop sense. A decoupling capacitor is also used here to prevent spikes.

Ambient light sensor (a voltage divider with a photoresistor), a UART pinout for additional modules to be add in future and a transistor in series with a 2Watt resistor, is used to adjust filament voltage/current using PWM. Because the circuit is designed to be powered by a power plug adapter the filaments are connected in series to reduce current darw and they are supplied directly from +12V.

There have been also used 6 RGB leds, one under each tube, filling in the tubes with more color and making it more impressive. The color change depending on the selected menu. 

Green: Time

Blue   : Date

Red    : Alarm

They are also supplied directly from the power plug adapter in order not to overload LM7805 and increase it's temp.


The main circuit.

The tube segments are connected in parallel via the bus to MAX6921 and a FET is used to turn on/off the chip. Atmega168 is connected with ISP to MAX6921. A 32,768KHz crystal is used to count the time. Also a buzzer has been used for alarm mode and button press feedback.

Crystals with frequiency 32,768KHz is used in RTC's beacuse they make perfect division with 128.  32 768 / 128 = 256. So we use this crystal with a clock prescaler of 128 and we have a counter (max value of counter 256) overflow interrupt occured once a second with accuracy of 0.002% depending on crystal.

Finall design photos:

The PCB Desing:

IV-11 VFD tube Clock March 2012 - PCB IV-11 VFD tube Clock March 2012 - PCB

Showing Time (GREEN Light).

IV-11 VFD tube Clock March 2012 IV-11 VFD tube Clock March 2012

Showing Alarm (RED Light).

IV-11 VFD tube Clock March 2012 IV-11 VFD tube Clock March 2012

Showing Date (BLUE Light).

IV-11 VFD tube Clock March 2012 IV-11 VFD tube Clock March 2012

And some more photos.

IV-11 VFD tube Clock March 2012 IV-11 VFD tube Clock March 2012

A photo with less light to capture clear digits. 

IV-11 VFD tube Clock March 2012



Update! Building a wooden case.

Gluing the frame Gluing the top

Gluing the top Painting the top

Soldering a new clock for the wooden case Comparing the two clocks

Wooden case Wooden case

Wooden case Wooden case - Front view

Wooden case - Rear view


  • steve
    07/05/2012 - 19:57 | Permalink

    Amazing project!! I really love your dedication on quality and detail!
    Keep up the good work

  • Jeroen
    07/05/2012 - 23:17 | Permalink

    Nice project!
    Could you post the schematic and board files?

    • 08/05/2012 - 08:18 | Permalink

      The schematic is posted above in pieces and explained what is what. The pcb layout is designed in Easy-PC and not in eagle because eagle's board layout limit is too small and it didn't feet. 

  • 08/05/2012 - 08:22 | Permalink

    Mmm I love this clock. Very clean looking, amazing work!

  • dario
    08/05/2012 - 08:47 | Permalink

    i WANT a kit or a ready made clock …………………………… make it PLEASE

    • 08/05/2012 - 08:55 | Permalink

      I'm planing to build a wooden case also. If you want i can inform you when i'll have it ready.

  • Jeroen
    08/05/2012 - 13:17 | Permalink

    Okay, thanks for your reply.
    What colors are the tubes? They look white/greenish…

    • 08/05/2012 - 13:20 | Permalink

      If you mean the segments color is green

      • Jeroen
        08/05/2012 - 23:07 | Permalink

        Yeah, that was what I meant, thank you!
        One more question, do you have any issues with EMC issues, with your switching power supply?

        • 09/05/2012 - 08:26 | Permalink

          When you say switching power supply you mean the voltage booster? And issues for what? for the clock circuit or for neighbor devices? Btw i have it working 7 days now and everything looks fine. No problem.

  • mfmjos
    08/05/2012 - 18:52 | Permalink

    I would be very interested in a kit!

    • 08/05/2012 - 21:51 | Permalink

      I'm thinking to sell it as kit if more people become interested for, in order to make mass production and have a good final product price. If you want send me an email to contact you when i'll have news.

  • Alex Holsgrove
    09/05/2012 - 00:18 | Permalink

    Hi Haris,
    Really love this build. Is the PCB layout available for download, or would I be able to buy one from you somehow? I'd love to build one of these. Do you also have the sketch available?
    Thanks again for sharing this.

  • vmatije2
    09/05/2012 - 02:03 | Permalink

    This is wonderful!
    Will you put the PCB files up for download? Never mind if it's done in Easy-PC.

  • 09/05/2012 - 08:23 | Permalink

    I'll inform all of you soon when i deside if i'm going to make it as a kit or not

  • Stella
    11/05/2012 - 16:03 | Permalink

    Loveable!!!!! I'd really like to buy one, cause constructing it will be impossible for me!!:)) 

  • dan
    17/05/2012 - 22:25 | Permalink

    I'd also be interested in a kit or just the pcb if you eventually decide to do one.

  • Rex
    17/05/2012 - 22:38 | Permalink

    I'd be interested in a buying a PCB or a kit if you decide to make more.

  • Shawn
    18/05/2012 - 00:23 | Permalink

    Ill take one too….

  • 18/05/2012 - 12:56 | Permalink

    I'm planning to sell it as a kit. So when i have news i'll inform all of you by sending email on the address you have submitted on the comment. If you want like my page on facebook

  • Joel
    18/05/2012 - 19:43 | Permalink

    Very nice and interresting clock ! Do you plan to share the software or give more details about its content (architecture, tube control, etc) ?

  • Sebastian Lemke
    03/06/2012 - 21:52 | Permalink

    I would like to get a kit, too!

  • Ira Burton
    20/06/2012 - 18:40 | Permalink

    Did you actually get the tube segments to light brightly using the push-pull transistor approach you mention above?  I have tried with a few different transistor combinations and can't get them to light above a dim glow.  Hooked directly to the power I can get the tubes to light beautifully.  I believe it must be that I am trying to drive the VFD from the low side of the NPN transistor, which can be problematic.  But it also may be that I have not found the right transistor combination. If you got it to work that way, what transistor combination did you find to work?

    • 21/06/2012 - 09:09 | Permalink

      I haven't tried to use a two transistor push-pull connection but i think it would be better if you use FETs. I directly used the Max6921.

  • Alan
    21/06/2012 - 00:52 | Permalink

    Interested is kit, and the price

    • 21/06/2012 - 09:11 | Permalink

      I'll add it soon in  When it is done i'll inform all of you who have write comments by the email you have submited.

  • Thomas
    04/07/2012 - 16:51 | Permalink

    Hi !
    It would be very nice if I ould get the Hex File for Atmega
    Super Projekt !!!

  • Brendan
    08/07/2012 - 18:38 | Permalink

    I'd also love a kit

  • 24/07/2012 - 10:11 | Permalink

    I truly enjoy looking by way of on this internet website , it holds superb content material .

  • marco
    09/08/2012 - 18:55 | Permalink

    Hi Harris,
    please give me a mail, when the kit is for sale.
    I need all parts except the tubes.

  • Willem
    12/09/2012 - 15:58 | Permalink

    Hello Haris
    Please send me a mail if you ready I need all parts except the tubes.
    Regards Willem

    • 13/09/2012 - 07:38 | Permalink

      I’ll send you back when i have the PCB’s. I was in summer vocation when the PCB’s came to my shipping address and because nobody was there to receive them they sent the package back. So i’m waiting for them to resend it when they receive it. (Dummy delay for no reason)

      I’ll keep you informed

  • marco
    09/10/2012 - 17:09 | Permalink

    I am still very interested. Please send me an email, whenever you have news 🙂   1kthx

  • dave
    11/10/2012 - 16:53 | Permalink

    I would love to see a kit that includes the bare PCB and either a programmed micro or file to burn the avr.

    • 11/10/2012 - 17:56 | Permalink

      Well this is in plan. I had placed an order for some pcb’s to make some samples and add this project to kickstarter or indegogo but the pcb’s never received due to summer vocations. No body was here to receive them so two months now the pcbs are on the way to turn back. I’m waiting for the manufacturer to receive them and ship it to me again. I promise i’ll inform all of you by the time i receive the pcbs and make ta campaign. 

  • marco
    01/11/2012 - 15:44 | Permalink

    "I promise i’ll inform all of you by the time i receive the pcbs and make ta campaign."
    Thumbs up! My already bought tubes are bored 🙂

  • Perlinpinpin
    12/11/2012 - 12:18 | Permalink

    I would be very interested in a kit too !
    Bonjour de France

  • Hubert
    15/11/2012 - 21:53 | Permalink

    I would be very interested in a kit too. Your clock is fantastic.

  • Alexander
    23/11/2012 - 15:27 | Permalink

    Και εγώ ενδιαφέρομαι για ένα κιτ.

  • 25/11/2012 - 17:44 | Permalink

    I would be very interested in a kit too.

  • Isaac
    04/12/2012 - 05:52 | Permalink

    I was wondering about the anode and grid voltage needing to be 60V.  The datasheet I got with my IV-11 tubes stated that the voltage is 25V.  It states that the maximum voltage is 70V; so 60V isn't harmful.  I was just wondering if 25V will do or if it makes the display dim.  I bought the tubes and an MM5316 28 pin DIP clock chip, which is supposed to directly drive the VFD segments in order to make a clock.  I then found your page when I was looking for an eagle file for the IV-11.  I may just do rat's nest wiring on a blank perf board.

    • 06/12/2012 - 10:45 | Permalink

      The tubes anode can light from about 15Volt to 60-70Volt depending on the lightness you want.  

  • marco
    10/12/2012 - 15:54 | Permalink

    Hi Harris, doesn´t like to push you, but can you estimate when you´ll get the PCBs?
    If it´s too far in the future, I would also appreciate just to obtain the other components and preprogrammed uC…

    • 10/12/2012 - 17:27 | Permalink

      Hello, thank you for your intereset. I received the PCBs today and i’m on the way to make some software modifications adding more features and making it more stable. After i finish these changes i’ll put the project on indegogo. I’ll make you know when it is ready in order to support it and request one kit or a ready clock. 


      • marco
        08/01/2013 - 13:35 | Permalink

        That is fantastic. What a coincedence, you just received the PCBs the same day as I asked.

        So the tediosness of my tubes seems to be over soon. 🙂

        Rock & Roll! Marco

  • 11/12/2012 - 19:09 | Permalink

    I have to thank you for the efforts you have put in writing
    this blog. I’m hoping to check out the same high-grade blog posts by you later on as well. In fact, your creative writing abilities has motivated me to get my very own blog now 😉

  • contem
    27/12/2012 - 00:32 | Permalink

    Finally a purpose for my iv12 or iv11 vfd’s laying around for years.

  • Reinoud
    07/01/2013 - 17:29 | Permalink

    Great blog , please over PCB and VFD driver(max 6921) in a kit .

  • 07/03/2013 - 03:35 | Permalink

    Very cool, made me want one: . No problems with wiring the filaments in series? I thought about that since it would be easiest, but was a bit worried about a brightness gradient along the set of tubes.

    • 08/03/2013 - 08:41 | Permalink

      There is a small brightness gradient but it isn't visible to the human eye

  • Charles
    07/06/2013 - 04:22 | Permalink


    I would be interested in a PCB and pre pro-grammed chips and a parts list to build the board, thanks

  • Ronny
    09/06/2013 - 14:08 | Permalink

    Really nice clock!! I too would be interested in a PCB and pre pro-grammed chips and a parts list to build the board, thanks

  • Jimmy
    20/06/2013 - 05:27 | Permalink

    Hi, Just leaving a comment so I can get a notification when you have the PCB's. Got some IV-11's on the way!

  • George Keller
    25/06/2013 - 04:07 | Permalink

    Very nice work and a clean looking case. I too would be interested in a PCB and pre programmed chip, and a parts list.

  • Charles
    07/07/2013 - 06:00 | Permalink

    I'd lke a PCB board and a programmed chip, how much?

  • Mike Vogl
    25/01/2014 - 10:10 | Permalink

    Hi Haris,

    Can I buy a PCB and programmed chip , parts list ??

    How much do they cost and shipping to australia ?


  • Graham
    27/01/2014 - 02:12 | Permalink

    Hi Haris

    I've not seen any post from you in sometime, I wondered if you sold all the boards or that are still available from you along with any code /  AVR ?





    • 06/03/2014 - 19:48 | Permalink

      Hi Graham,

      Yes there are some available boards. 

      You can also follow the facebook page

      I’ve not written any post for so long because i have no free time but i’ll make it soon. 

  • Marco Radini
    20/02/2014 - 20:38 | Permalink

    Hi Haris ! Till now I build nixie clocks with PICs. Found on the net schematic AND .hex file to program

    the PIC…never Atmega… I have a lot of IV-11…. need PCB and preprogrammed chip….

    Can you help? TIA


    • 06/03/2014 - 19:44 | Permalink

      You can find the information you are looking for on this article.

      Thank you!

  • 17/01/2015 - 23:03 | Permalink

    I am interested in purchasing one of the IV-11 clock kits. Do you have one available? I would also be interested in an assembled and tested unit. Can you provide me with the prices of what you have available? Please E-mail me directly if you want to sell one of these units?

  • Gerard
    20/03/2016 - 01:00 | Permalink

    I am interested in purchasing a kit or completed clock.

    please email details of cost and where to purchase.


    thanks Gerard

  • James Robbins
    08/06/2016 - 01:20 | Permalink

    Do you sell kits or assembled units?

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