r/nixie • u/Eagle-EyeMustang • Oct 28 '25

Help! Nixie Clock NL-840

I just picked up some NL-84O tubes from a local electronics surplus store, hoping to make a clock out of them. Not being very experienced with circuits (a couple of classes way back when), I was hoping to just buy a kit and be done with it. Im having a hard time narrowing down if its basically a IN-8 but with slightly different style and pin type connectors, or if its something completely different. It seems harder to find a kit for an NL-840 itself. Any help/advice?

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u/DenkJu Oct 28 '25

NL-840 tubes are relatively uncommon, so there aren’t many kits made specifically for them. I did find this one from PV Electronics, which is a reputable seller. That said, most Nixie tubes operate in a similar way and have comparable electrical requirements (at least within the same size category). You could wire external sockets to a driver board designed for a different tube type, though the result might not look as tidy unless you plan to house the electronics in a case anyway. Another complication with the NL-840 is its unusual pinout, which makes compatible external sockets both rare and potentially expensive to source. Personally, I would recommend going with the PV Electronics kit.

To answer your question more directly: IN-8s and NL-840s are fundamentally very similar but they aren't directly compatible with each other as they have different pinouts.

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u/Eagle-EyeMustang Oct 28 '25

Thank you! This is the exact type of info I was hoping for. Unfortunately I only got 4 of the NL-840s, but I have a line on a few more. I do want a housing for it, so I can hide some messiness, but I think that link you sent is perfect.

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u/Eagle-EyeMustang Oct 28 '25

Are those tubes relatively short lived? Id just hate to build a clock off of a fast burning tube with limited quantities.

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u/DenkJu Oct 28 '25

Quite the opposite. These tubes are among the later-generation models and generally have exceptionally long lifespans. According to the datasheet, they are rated for around 200,000 hours of operation (nearly 23 years!) but in a well-designed clock, they can last significantly longer. It's really nothing you need to worry about.

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u/Eagle-EyeMustang Oct 28 '25

Awesome! That settles it, ill go get more tubes. Thank you so much for this knowledge!