A Nixie, maybeWhether or not the type IN-9 linear indicator tube used in the project is really a Nixie device is debatable and some food for thought may be found in the above mentioned Q & A article. IN-9’s are normally filled with Penning-enhanced neon gas mixtures although some rare versions exist filled with argon-ish mixtures instead; these tubes have a somewhat higher ignition voltage, and the light column has more of a violet than a light red/orange hue.
The magazine article published on this thermometry project sets a standard by having a few excellent paragraphs on the history and basic operation of the IN-9 linear indicator tube. It also discusses some of the designers’ compelling reasons to go for the IN-9 instead of the better known IN-13.
A dozen IN-9’s pleaseOccasionally forced to harken "at the wrong end of the customers complaints line" here at Elektor I can safely say that “where can I get the %$@*& parts” ranks high in the Top-10 of queries we receive on the project publications in Elektor Magazine. When it the past it was necessary to recite a list of about 30 companies along with their telephone numbers, today the best, not necessarily flippant!, reply is: (1) Google and (2) Ebay. Sadly many of our older readers still fear ordering from abroad with the associated payment procedures. In the case of the Nixie Bargraph Thermometer project, if you insist on scraping all the parts together yourself instead of buying the kit, be advised that IN-9 tube device will not be available from “certain mail order companies” or local suppliers unless you live in the Ukraine, where these parts are still manufactured and stocked it seems. To the modern electronics industry, the IN-9 is dead, buried, or “obsolete”.
I decided to overcome my own hesitations on “Russian suppliers on the net and all that” by going on Ebay, find an IN-9 supplier and order one. Just for larks. The price seemed to be in the $5-$10 band apiece from several reputable suppliers mostly in Germany, The Czech Republic, the US and the UK. But I was intrigued to see one Ukrainian supplier offering 12 pieces for €27.95 including postage. Even if I scored three working pieces from that lot that would be a success and allow me to share out in the lab and among Friends of Retronics. An ‘expedited mail’ option was indicated on EBay but at a cost of €12.50 I decided in favour of some patience. I paid using my PayPal account and duly got a notice from the supplier about due receipt of payment at his end, along with a tentative delivery date about 3 weeks on.
The parcel actually arrived as scheduled and was not sanctioned by the (German) customs with an import duty.
The packaging is good & solid Ukrainian style with a type of brown wrapping paper I thought I’d last seen 40 or so years ago for bicycle parts. The IN-9 tubes were all intact though and the packaging note was, well, close to comprehensible.