I tested all 12 tubes with my Wandel & Goltermann 0–300 V, 0-100 mA adjustable power supply normally used for repairing tube radios and reforming electrolytics. The total investigation time was about 1 hour. Of the 12 (old school: one dozen) IN-9 tubes I received from my Ukrainian “frriend”:
  • one failed to light to the top of the bar;
  • two were argon types (blue readout); hey ho!!
  • one has a 2-cm permanent dead section at about 70% up the bar.

Try as I might to get all tubes to work using a lean & mean version of the burn-in process described in the magazine article, sadly the 2 patients could be restored to normal life, which leaves a net investment of €27.95 / 10 = €2.80 apiece, compliments from the Ukraine and Ebay.

The Elektor kit

A good deal of the success of the Nixie Clock and the VFD-Tube Clock publications must be due to Elektor supplying pre-cut acrylic sheet (Perspex®) parts to build a transparent housing for the electronics. The effect together with LED colour lighting is just right to reinforce the totally retro look of the Nixie tubes with their soft, charmingly imprecise numbers indicated by mesh structures. The effect is alluring to non-electronicists. A sort of old James Bond tech. In the case of the thermometer, the vertical bar imitating the mercury column in a traditional thermometer is the electrically activated section of the neon gas column inside the IN-9 tube. The height (i.e. C/F value) is controlled by periodically interrupting the current through the IN-9 tube. A small drawback of this technique is that it slightly degrades the linearity of the tube as a readout device, but reportedly can easily be corrected in the software. In practice, the readout is charmingly imprecise.

The kit is well packaged in a sturdy cardboard box (190 x 110x 50 mm) and has separate plastic bags for:
  • Arduino Nano
  • connectors, jumpers and trimpot
  • passive parts (R, C)
  • inductor
  • ICs, IC sockets, transistors, diodes, LED
  • three 15-cm long prefabricated wires;
  • nuts, bolts, standoffs, case feet;
  • small acrylic sheet parts, rubber parts, heat shrink tubing.
The 70x 70 mm PCB comes wrapped in light paper and the larger acrylic sheet parts are not packaged separately. The finish of these parts is excellent and they are protected by light green adhesive film you can peel off with some effort. The IN-9 tube comes rolled in two layers of bubble wrap.
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About Jan Buiting

Jan Buiting (1958) has been active in electronics and ways of expressing it since the age of 15. Attempts at educating Jan formally have so far yielded an F-class radio amateur license, an MA degree in English, a Tek Guru award, and various certificates in ele... >>

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