Nixie-based tube clocks

Is this (click on the image to see the full resolution picture of the madness):


KABTronics TubeClock


I'll be testing myself against it in a fight to the death:

  • 215 Transistors
  • 518 Diodes
  • 472 Resistors
  • 101 Capacitors
  • 10" x 14" Printed Circuit Board with silk screen symbols indicating component locations

Who will win? (My money is on the clock).


KABTronics web site


Single Digit IN-18 Nixie Clock

Under my desk there is a box of IN-18 tubes which I have been meaning to use for a while, some of the tubes are perched on the top of the box, threatening to fall out, and it really way time to do something with them. Browsing EBay lead me eventually to the fantastic array of gadgets on the site, and I just had to have one of the cute, beautifully designed Single Digit Nixie clocks that would fit with a tube from my overflowing box.

The ordering process went beautifully, and the assembled clock arrived within 2 weeks, well packed and in a small but sturdy cardboard box. The clock comes without a tube, but the process of fitting a tube is really straightforward, because there are pin sockets which seem to fit snugly, but without the idea that you are forcing the tube into the socket.

Single Digit IN-18 Nixie Clock as delivered

One of the beautiful things about this little clock is that it needs only a USB 5V supply to make it run. It is quite power efficient, and doesn't consume much energy, and doesn't get hot. While diplaying the time, it shows the tens or hours, hours, tens of minutes and minutes one after the other. To help you understand the time more easily, the single hours and single minutes also light up the right hand neon bulb as well.

Setting the options is a bit fiddly. Personally I had a bit of trouble understanding the menu structure, and had to keep reading it attentively to be able to set the clock, but that is the cost of having a clock with only a single digit and lots of options. Once the clock is set, you won't have to set it again very often, because the time is preserved by a battery driven Real Time Clock when there is no power. The time keeps counting even when the clock is turned off. You can see the data sheets in in English or in Chinese.

179 EUR (Kit) & 50.34 EUR (Tubes)

Welcome to the Black’n’wood review. I’ve reviewed several other Nocrotec clocks before and this one comes to us from a combination of sources. Dieter of Nocrotec worked with YanZeYuan (严泽远) to develop the electronics for this device. The tubes are sold by and the kit components are sold though

The first thing that you notice is that this device uses end view tubes. The default set are  Chinese QS30-1 tubes. These are uncoated tubes with proper 5s and 2s. These are 30mm diameter tubes that use a standard base. Consequently, there are multiple tubes that can work as substitutes. For example, I have swapped out my tubes for the orange-coated GN-4 tubes (more on this later). Nocrotec has a list of substitutes that I have included at the bottom of this review for reference.

While we’re on the topic of tubes it is worth talking about viewing angle. Side view tubes typically have a wider viewing angle (both vertically and horizontally) than end view tubes. On end view tubes, the digits are stacked on top of each other in a small cylinder. This means that the numeral 9 is easier to see than a 6 because the 9 is at the front of the tube and the 6 is at the rear (digits are not stacked in numerical order). This clock is no exception. Because of this, the clock will ideally be mounted somewhere around eye level. I don’t consider this a problem because it is the nature of all tubes like this.

The enclosure clearly follows the design of some of the original Nocrotec clocks. The wooden base and metal plate look nearly identical to my X2000 []. I am a huge fan of this design; it gives the clock a nice luxury feel. The case itself is 287mm wide, 49mm deep, and 75mm tall (11.3” x  1.9” x 2.9”). The tubes protrude slightly but only by a few millimeters.

A small feature that I wanted to call out is the colon indicator tubes. They are not led; they are tiny neon bulbs. This was done to match the color of the nixie tubes but it also gives the device some subtle detail. For example, the top of the tubes are crimped and this causes the light pattern to be different from any led bulb. The tubes flicker somewhat; you can see the flow inside of the tube bouncing around. You don’t notice these details at first but when you start staring at them you quickly appreciate them.

The tubes are illuminated with blue LEDs which fade on/off every two seconds by default. You can order other colors (ocean green, deep green, white, purple) and if you don’t like the backlights, you can simply disable them. Earlier I mentioned that I swapped out the tubes with orange-coated GN-4s. The tubes are surrounded with foam padding to prevent light leakage from around the tube. With this surround and the orange coating, the backlight is almost completely blocked. Considering that orange and blue are opposites, this is not really surprising but it does mean that if you want to use the backlight feature, you should stick to uncoated tubes.

Keeping track of the time can be done a few different ways. The device comes with an internal crystal so you can simply set this clock like any other and let it run. You can also use a GPS receiver or a DCF77 receiver to set and maintain the time. The DCF77 and GPS options are external devices that you can purchase at a later time. Enabling them is as simple as changing a menu option on the device.

There is another interesting feature that may be of interest to some users. The Mini DIN connector can be uses to switch con and off other devices when then alarm sounds. You will need to add a relay to switch anything but the +5 V output may be interesting to some users.

Overall, this is a solid design. It offers a robust feature set and looks nice at the same time. I’ve been able to play with this clock for a few weeks and I thoroughly enjoy it.


Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Black'n'Wood Nixie Clock

Tube substitutes

10TU26, 122P224, 154-0327-00, 1970-0002, 5031, 50347, 5037, 5092, 5092A, 6770, 6844A, 8037, 8037(B-5031), 8421, 8421(B-5092), 8421/5092, B-5031, B-5031/6844, B-50347, B-5037, B-5092, B-5092/8421, B-5092A, B-6844A, BD-302, CD102, CD18, CD24, CD26, CD32A, CK6844A, CK8037, CK8421, CV5278, CV9316, CV9732, F9057, F9057A, F9057AA, GN-3, GN-4, GN-4A, GN-4D, GN-4E, GN-4P, GNP-4A, GR10M, HB-106, JAN-6844A, JAN-8037, JAN-8421, JAN-CB-6844A, JAN-CZ-6844A, LC-511, LC-513, LC-513A, M2726-102500, M2726-102600, NE-50347, NL-5031, NL-50347, NL-5092, NL-6844, NL-6844A, NL-8037, NL-8421, ST12C, SZ1-1, SZ3-1, SZ-8, Z510M, Z520M, Z5600M, Z560M, ZM1020, ZM1020/01, ZM1022, ZM1022p

Links:'s new Leon clock is now shipping. This is a solid looking design that has the interesting addition of a microphone stand mount on the bottom. This means that the device can be mounted small desk stand to make it really stand out. I particularly like the red corner caps of this design - it almost looks like a 1950's hot rod. This thing looks nice!


From the site:

Leon is Mr.Nixie’s fourth creation of a Nixie clock series starting with the IN-2 "Laura", IN-17 "Lars" and IN-12/17 "Lena" Nixie clocks. Based on the past experiences of hundreds of sold kits and the wishes from our customers, the software was radically re-written and is now backed with a lot of new features. Also an "ultra cool" HV converter design was introduced, which minimizes the heat created by the inductor / switching transistor to a maximum of only 30°C. This results in highest efficiency > 90% and the possibility to power the clock from a single USB power source. In the same way the EMI noise was dramatically reduced. The electronics of Leon is packed into a very flamboyant OEM aluminium enclosure from the design-series "Chac" of Fischerelektronik in Lüdenscheid / Germany. An optional glas desktop stand from König & Meyer, which fits into the 3/8" threat on bottom is available.


  • Hours, Minutes and Seconds display
  • 3 x 2 multiplex for less tube noise and higher brightness; based on a modern Supertex HV driver
  • Selectable 12 or 24 hour display modes
  • Uses a Quartz Crystal Oscillator as the timebase with software adjustable accuracy
  • Programmable leading zero blanking
  • Date display in either DD.MM.YY or MM.DD.YY or YY.MM.DD format
  • Programmable date display each minute or selectable with a single button push
  • Scrolling display during fading-in the date or standard display change
  • Alarm with programmable snooze period
  • Optional DCF / WWVB / MSF / GPS sync. with status LED; prepared for fitting internal the ASK receiver module from the "Wireless GPS connection"
  • Dedicated DST button for easy switching between DST and standard time
  • Super Capacitor backup keeps time during power outages for more than 24 hours.
  • Simple time setting using two buttons
  • Five programmable column neons settings (Flashing AM/PM indication, illuminated AM/PM indication, always flashing, always on, always off)
  • Seconds can be reset to zero to precisely the set time
  • Programmable night mode - blanked or dimmed display to save tubes life or prevent sleep disturbance
  • Weekday aware "Master Blank" function to turn off all displays on weekends or during working hours
  • Separate modes for column neons during night mode
  • Standard, fading or fading + scrollback display modes as an eye-catcher
  • "Slot Machine" cathode poisoning prevention routine, disabled during night mode, selectable time
  • Programmable RGB tube lighting – select your favourite colour palette
  • 729 colours possible. Have a different colour with selectable brightness of your choice every hour or autochanging colours with variable speed
  • High efficiency „ultra cool“ HV converter, power consumption less than 2.5 VA even when RGB lighting is fully turned on
  • Powered from a single Mini USB outlet (from your PC, MP3- or a cellphone charger)
  • All user preferences stored in non-volatile memory


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