It more or less looks like an ordinary vacuum tube, but if you look closer inside the glass, you can see a bunch of overlapping numbers(0 to 9). This kind of lamp was used a lot during the 60's.

This lamp comes from a big calculator(bigger than a typical modern computer) that I disassembled when I was 10 years old. This tube is 1" high, is model no. CD78 and is made in Japan. Nixie tubes like this exists in many sizes, even 6" tall.

I would like to have 6 identical tubes like this one, to build a clock. In my opinion, a nixie display is way nicer than a LCD or LED display.

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It took me ten years to learn how to make this tube work. It needs 130Volts, and I had never tried a voltage this high on it.

They are very easy to control. The positive voltage goes on the pin connected to the grid. Next, you just need to tie the negative wire to one of the number pins to make the same number illuminate.

I designed a circuit to make the lamp count continuously. Here is what it looks like:

Here is the schematic: nixie_counter_shema.gif. NOTE: The transistors are MPSA42.
And here is an image of the PCB layout in postscript: pcb.ps

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To learn more about Nixie display tubes, visit this site:
Couting & display tubes

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