Six Digit Nixie Clock kit

My first Nixie clock kit was a limited production, now sold-out.

If you are able to make your own circuit board, I can still supply the programmed PIC microcontroller and most other parts.

Combines a modern microcontroller with the retro neon orange glow of Russian IN-14 Nixie tubes

This nixie clock is is very configurable – it has over thirty options. Customise it to look and work the way you prefer – (see the features list below).(Click images to enlarge)

Timekeeping options are flexible – it can use the onboard crystal oscillator or sync with the mains frequency (50 or 60Hz). It can decode time signals from external precise time signal devices.

With a suitable interface, you can connect it to MSF, DCF77 or GPS receiver modules(not supplied), a PC serial port, a one second pulse supply or a WWVB (USA) receiver (Experimental only).

Instructions and diagrams for you to make the required simple interface circuits and connections are provided.

The kit does not use any surface-mount components and the assembly manual provides detailed instructions with photos of each stage of assembly.

However, this kit uses many components and generates a high voltage, so is not suitable for beginners.

You must provide a suitable case and AC adapter (wall-wart)

Nixie Clock Features
  • The core of the clock is a Microchip PIC16F876A 8-bit CMOS microcontroller ic.
  • It is programmed entirely in assembly language code.
  • The nixie tubes are driven in a 2*3 line multiplex which provides fast display refresh,lower driver chip count and reduced power consumption.
  • Uses six large IN-14 Nixie tubes with 19mm (3/4″) high digits.
  • Normal clock timing is provided by the cpu crystal which can be finely adjusted and stored using the pushbuttons.
  • Alternatively, the clock can derive timing from the 50 or 60Hz mains frequency (provided an AC power adaptor (Wall wart) is used).
  • It has the option to connect to MSF (UK), DCF77 (Europe) or GPS time receivers in order to obtain accurate time and date updates.
  • Can be interfaced to a Windows 98 or XP computer serial port to synchronise with the PC time (“NixieSync” software is supplied)
  • The time can increment under the control of an external 1pps time pulse.
  • An Experimental (untested on live broadcasts) option to sync to a WWVB receiver (USA)is also provided.
  • The high voltage for driving the nixies is controlled and regulated directly by the microcontroller using Pulse Width Modulation and regulated using P.I.D algorithms.
  • It is continuously monitored for possible high voltage fault conditions and has “soft start” at power on with diagnostics, fault indication and overload shut-off.
  • The high voltage is initially pre-set to 180V, it can be adjusted if desired using the pushbuttons and stored in EEPROM memory.
  • All clock option settings are easily adjusted using just two pushbuttons and are retained in the controller memory during power-off.
  • The clock is fully configurable with over 30 main options with many setting choices – configurations are retained in memory.
  • Digit cross-fading effects (5 levels) – blends digits as they change.
  • Scrolling date effects – 4 options for scrolling the date plus a random effect selection option.
  • Manually controlled display brightness selection (5 levels)
  • Time controlled display dimming and/or turn-off.
  • Light level controlled display dimming and/or turn-off to increase tube life.
  • Digit cycling effects – 8 different effects plus a random selection option. The cycling effect speed and run intervals are configurable.
  • A special long cycle effect can be set to run at midnight – to help prevent Nixie “cathode poisoning”.
  • 12/24 hour time modes with leading zero blanking options.
  • Date display in UK/US or International format with display interval and duration configurable.
  • Leap year automatic adjustment.
  • Selectable time zone – The clock can offset the time received from MSF/DCF77, GPS or WWVB sources by up to +/- 14 hours.
  • Six bright tube illumination LEDS (Either Blue or optional UV (Purple) which can dim along with the nixies and configured to be continually on/off or switch on or off during date display etc.
  • Dimmable neons for colon display – these can be controlled in various ways to be on/off/flashing(two speeds) or indicate AM/PM.
  • A (decimal point) type nixie AM/PM indicator which is configurable and dims with the display.
  • One button can be reconfigured from it’s default dimming function to switch between 12/24 hour time, show the date,toggle cross-fading or switch to a completely different whole clock configuration for personal preferences.
  • Because it is powered from a low voltage, It can be used worldwide (with an appropriate ac adapter)
  • There is a user re-settable tube hours usage counter.
  • Two status LEDs provide an indication of normal clock activity, external time pulses and any errors. These can be switched-off when not required.
  • The whole clock configuration can be reset back to “as-new” defaults if you ever wish to.
  • A CD containing a detailed, illustrated assembly instruction manual with full circuit diagram in PDF file format together with a user manual and details on interfacing to optional time sources, plus a circuit description and datasheets for the main components.
  • Compact PCB dimensions: 150mm x 60mm and 20mm underside clearance. (5.9in X 2.4in X (0.79in)
  • A few CAD “dxf” and “emachineshop” files to act as templates for your possible case design are included.
Optional connection to external time sources – technical requirements

The clock may optionally be connected to an MSF (UK) or DCF77 (German) time receiver. The manual shows details of simple interface circuits for connection to commercially available modules or for modifying cheap complete “radio controlled” type clocks instead.

GPS connectivity requires the use of an “OEM” GPS module meeting the following specification –

  1. Data output levels – TTL or CMOS compatible (0-5V)
  2. Serial comms – 4800 baud, 8 bits, No Parity, 1 Stop bit
  3. Protocol – NMEA 0183
  4. Required Sentences – RMC (GGA may also be used in addition if available)
  5. Low power consumption – If powering the module from the clock 5V output.

Alternatively, it can be connected to an accurate (TTL/CMOS levels) 1pps time pulse to increment the seconds on each positive going pulse.

Another option is to synchronise to a Windows XP or 98 PC via an interface to the computer serial port. The easy to install software for this option is included on the kit CD.

Finally, an “Experimental” WWVB (USA) timecode decoder option is provided.
It is not possible to receive WWVB time transmissions in the UK, so it can not be fully tested.
Simulated WWVB timecodes have been decoded ok – it “should” work if you wish to try it.


Download the user manual for the kit here:

Six tube Nixie clock user manual

Download the IN-14 Nixie tube datasheet here:

IN-14 datasheet

Please contact me if you wish to download the full set of manuals for this kit.

Microcontroller chip only
Buy from shop

Nixie Clock Kit  – SOLD OUT (updated 30th October 2007)

This kit generates a high voltage.
Only persons who are competent at electronics assembly and understand the dangers of high voltages may attempt to assemble this kit!
Safe assembly and operation of this kit is the users responsibility.
This information is provided ‘as is’.
No responsibility is accepted for any damage, injury or death as a result of assembling this kit.
The assembled unit must be properly en-cased to prevent contact with high voltages and kept out of reach of children.