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I'm working on a design with some Nixie tubes (a clock, specifically to start, but I'm gonna have a ton left over for other things), and due to the rather expensive nature of the K155ID1/74141 ICs, I'm not real eager to just plug things in the way I think they should go and see if it blows anything up.

My understanding is that the ICs should take +5V and GND from my controller (Arduino, for instance) or directly from my power rail, as well as taking the BCD in the DCBA pins from my controller. To strike the Nixie tubes, I need 170+V at a relatively low amperage. From what I've read about the BCD decoder, my "outputs" (pins 1, 2, 8, 9, 10, 11, 13, 14, 15, 16) can be attached to the cathode pin on the Nixie tube corresponding to the number I want to light up.

I assume then that the ground pin on the BCD decoder needs to share a common ground with both the power source for the Nixie tubes and the power source for the IC itself. My question is, will that voltage (even with the low amperage) blow up my K155ID1's?

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  • \$\begingroup\$ I have Nixie clocks with 6 of K155id1 and IN-14 running continiously since 1994, nothing happens to them. Also, you can easily replace k155id1 with 300V or so sot23 transistors and low voltage decoder. \$\endgroup\$ – Nikolay Feb 8 '17 at 23:04
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Yes, all the components need to share a common ground (if you're paranoid you can have the high voltage ground connect to the low voltage ground in one place through a ferrite bead). The "outputs" you're talking about for the BCD are just acting as switches to ground, so they don't experience the high voltage and small current on the same time. When turned on (switched to ground), most of the voltage is dropped on the Nixie tube segment and series resistor. When switch off however, they'll see the full voltage. It's difficult to tell from the linked data sheet what voltage they can handle, the part that's in English talks about a DM54/DM7441A, while the Russian part looks like it's about the K155ID1s. The two parts of that datasheet can also be found independently online, so I'm not sure if they're supposed to be pasted together. It certainly looks like people have been using these with 170VDC, so they very likely work, though the lifetime may be degraded. I'd say go for it, the chips are only $0.90 some places.

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  • \$\begingroup\$ Yeah, $0.90 with $8.00 S&H... :( That's where I ordered them from, but I ordered enough stuff to make the S&H worth it. Ordering the only similar part I could find from Mouser was ~$7.50. Prices everywhere relevant to shipping puts them $6-8 depending on quantity. But your answer seems to line up to what I had thought, the degraded ICs will probably still last longer than the tubes. \$\endgroup\$ – Nathan Wheeler Nov 14 '12 at 5:37

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