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A "Strawberry Clock" ?

The IN-28 Strawberry Clock is an unique single-digit wall clock which displays time in sequences, 10's hours, 1's hours, 10's mins and 1's mins and simulates a 7-segment display with nine IN-28 "Nixie Dots" tubes. So far, kits for these tubes are not yet available on the market, especially since these tubes needs to be controlled as a Thyratron. So you'll get an unique piece of jewelery which also serves to "de-celerate" the everyday pace of life hectic as the time can not be read just with a glance.
The name "Strawberry" stems from the fact that in addition to the standard cover also face covers are offered with different colored mirrored acrylic glass and different motifs, including the strawberry as shown here.

But how can the clock display the time with only a single digit?

The clock displays the time in a sequence of four digits, each with a small pause between the individual numeral and a longer pause at the end of the sequence. It's really intuitive, and once you have understand the sequence, reading the time is very easy.

What are IN-28 Nixie-Dots ?

This tube was used earlier times in large size displays in Eastern European train stations. In addition to high brightness (influence of sunlight), it was also important to have simple control, high reliability and an extremely long service life - always with respect to the technology available 50 years before.
Therefore, the IN-28 was equipped with a "ignition electrode", like the gate of a Thyratron, the forerunner of today's Thyristor. Although the behavior of the IN-28 through this ignition electrode is similar to that of a switching tube (such as the small TX5-B Thyratron), the focus was more on brightness and easy driving than on the switching function.
The tube was in earlier times operated via a powerful series resistor to the unsmoothed bridge rectified mains voltage with an average current of up to 12 mA; by a burning voltage of 185 V this corresponds to 2.2 watts. At this power the tubes become fairly warm.
By choosing the "breakdown voltage" of 350 V, the tube does not ignite when the above-mentioned rectified full waves of the mains voltage is applied to the anode and cathode and the ignition electrode was not activated.
Only when about 170 V via a high-value resistor is applied to the gate, the glow discharge starts. And it persists, even if you take away the voltage from the gate.
You can only "extinguish" or switch off the tube if the voltage between the anode and cathode drops below the keep alive voltage. Therefore, a non-smoothed DC voltage was used in earlier days. The voltage zero crossings clears all tubes 100 times a second; and the tubes are ignited again when the voltage increases and if the necessary gate voltage is applied.


  • Displays hours and minutes in a sequence
  • Selectable 12 or 24 hour display modes
  • Thanks to the high brightness compared to Nixietubes the display is readable even in sunlight
  • Automatic brightness control for longer tubes life
  • Uses a Quartz Crystal Oscillator as timebase with software adjustable accuracy
  • Simple time setting using two buttons
  • Seconds can be reset to zero to precisely set the time
  • Optional GPS / NWTS sync. with status LED; prepared for fitting the ASK receiver module from the „Wireless Set“
  • Dedicated DST button for easy switching between DST and standard time
  • Super Capacitor backup keeps time during power outages for some hours.
  • For fixed installation the DC power jack can be replaced by a screw terminal with reverse polarity protection
  • Flushing box power supply TRACO TIW 24-112 available
  • Programmable night mode: Display and LEDs are blanked and the HV supply is turned off
  • Standard or fading display modes as an eye-catcher
  • All user preferences stored in non-volatile memory
  • No small SMT design but through hole components
  • Constant current drive of the tubes for extended lifespan
  • White 15 VDC EU wall mart power supply with white connection cable is optional available
  • Different designed clock faces made with different colour mirrored Acrylic glass are available

  • Dimensions with standard clock face: oval 188 x 166 mm, height with tubes: ca. 50 mm
  • Weight: ca. 450 g
  • DC input: 12...15VDC 2A via 5.5/2.1 mm DC jack (positiv inner) with reverse polarity protection
  • Power consumption: between 0.5 and 20 VA (display brightness depending)

What you'll need:

  • 3 hour of your evening time with no hurry
  • A clear, well-lit area in which to work
  • Soldering station and fine electronic solder
  • Multimeter to check the generated voltages
  • Electronic tools
  • A loupe may be helpful
  • TX10 (Torx) and PH1 screwdriver
  • Download of the manual
  • Enjoyment of your work of course
  • 9 x IN-28 tubes (offered separately)

RFT receivers

NTP receiver
The modern art of time keeping:
Via Internet and a domestic Wi-Fi the time data will be received from a "timeserver-pool", converted into a pseudo GPS format and interpreted by the clock.
  • Easy placement
  • The NTP must be able to connect to a 2,4 GHz Wi-Fi network
  • Only onetime configuration through Laptop / Tab or Mobile Phone with the web browser
  • No software or App installation necessary
  • World time (UTC) is transmitted, which means that the clocks have to be configured once for the corresponding time zone and need to be set between DST and Non-DST twice a year by pressing a button
  • Can be used worldwide


Wireless GPS
The wireless way of time keeping, specially with multiple clocks:
The data sent by the GPS satellite system is received (similar to the car's navigation system) and converted into a 433 MHz signal, then transmitted intermittently and received from an internal fitted ASK module.
  • Placement the Wireless transmitter on a window frame with a clear view to the horizont is required
  • Wall outlet for powering the Wireless transmitter necessary
  • 433 MHz signal strenght up to 20 m indoor
  • Every clock must be equipped with an internal ASK module
  • One Wireless transmitter can be received by any number of clocks
  • World time (UTC) is transmitted, which means that the clocks have to be configured once for the corresponding time zone and need to be set between DST and Non-DST twice a year by pressing a button
  • Can be used worldwide, but specially intended for Export, therefore the manual is only available in english speech
These wireless components consist of the following devices
1.: A wireless GPS receiver with USB power supply for placement on a window frame.
2.: An ASK module for fitting into the clock.

If you want to use Wireless GPS synchronization for the first time, we recommend to order a Wireless Set 3 as all necessary components are already included. Later, to expand to every new clock, you only need an internal ASK module.


Look at RFT Receivers


Pre Order - Shipping starts end of February 2018

Complete electronic kit incl enclosure and semi transparent clock face

Version / Shipping to

Extras (Power Supplies and Clock Faces)

This clock faces will made individually and have a slight longer delivery time

Optional RTF receiver

Please choose
Shipping costs
Flat shipping costs of 6.50 or 7.50 EUR are added to cart
The prices of the EU versions includes the German 19% VAT.
Handling fees
Higher handling costs for export are already included in the item price exept of import duties, taxes etc. These charges are the buyer's responsibility.
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