| Made | Soviet Union |
|---|---|
| Digit height | 18 mm |
| Read from | the end |
| Decimal point | none on the IN-12A, one on the IN-12B |
| Size | 21 × 32 mm, 35 mm tall |
| Pins | 12, in a socket |
The IN-12 is the other Soviet Nixie tube I build clocks around. It works the same way as the IN-14 — ten wire digits in a neon-filled bulb, glowing orange — but it is read through the end of the tube rather than the side, and the envelope is shorter and wider. There are two versions: the IN-12A has no decimal point, the IN-12B has one.
Where they come from
Like the IN-14s, they are Soviet new old stock, made before the factories stopped and never used, and every one is tested before it is fitted or sold.
How long one lasts
The factory guaranteed 5,000 hours of operation and six years of storage — a floor, not an estimate. Beyond that the same rules apply as for the IN-14: hours lit, and whether every digit gets used. The six-tube acrylic clock cycles through all the digits every night so they wear evenly and stay bright.
How to change one
Socketed, never soldered: out with the old, in with the new, about a minute, no tools. The four-tube IN-12 walnut clock ships with a spare; the six-tube acrylic clock does not, and tested IN-12 tubes are sold separately.
Buying a spare
Tested spare IN-12 tubes fit every socketed Nixie Star IN-12 clock. They do not fit IN-14 or IN-18 clocks.
Clocks with IN-12 tubes: IN-12 clocks.
Figures are from the original Soviet factory labels in the tube-tester.com datasheet archive.