I got an email from amzfx<at>email.com with a link to this picture. I thought it was cool enough to blog. I figured that most Nixie tubes are driven by high voltage transistors such as the MPSA42, which are only a few cents apiece. In this case, it looks like the tube is driven by ten optoisolators. I didn’t think that most optoisolators were able to handle 150 volts. Maybe these are optoisolated SCRs? Nah, SCRs don’t work on straight DC. The opto’s are superior to the high voltage transistors because they isolate the Nixie’s high voltage from the rest of the circuit. But it’s hard to justify using them since they cost a lot more than high voltage transistors and the transistors do the job okay.
Another thing I hadn’t thought about is that since Nixie tubes don’t have filaments, they don’t take much power. In this case, it looks like the AAA cell is powering a single transistor DC-DC converter in the lower left, which supplies the high voltage. Since only a single digit is on at a time, I would guesstimate that the high voltage has to supply a current that is much less than 1 milliamp, or much less than 100 milliwatts from the battery. The controller doesn’t take much power, so the whole thing is really not a strain on the single AAA cell.
However, I will say that it’s impossible to beat the LCD displays for efficiency. I bought an indoor/outdoor thermometer with a LCD display from Ratio Snack over ten years ago and it’s still displaying the temperature 24/7 on the same AAA battery I installed the day I bought it.