# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/Db8U_FqASMR
- **Gondola URL:** https://gondola.cc/posts/69054409-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/3fea576f46.jpg
- **Posted:** 2026-08-12T14:06:32.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

A Nixie clock does not light up. It ionises.

Inside every tube sits a stack of wire cathodes, each one bent into the shape of a numeral and suspended in a low pressure neon and argon Penning mixture behind a fine mesh anode. Apply roughly 170 volts across the gap and the field strips electrons from the gas. The discharge collapses onto whichever cathode is pulled to ground, wrapping that single digit in a sheath of glowing plasma sitting a fraction of a millimetre off the metal.

The colour is not a coating or a filter. It is neon relaxing back towards its ground state, radiating on characteristic lines between roughly 585 and 640 nanometres. No pixel grid. No backlight. Just excited gas doing what excited gas does.

Building one is a genuine high voltage exercise:

- Boost stage: a switching converter lifts 5 or 12 V DC up to 170 to 200 V, classically an MC34063 or a 555 driving an inductor and a fast diode
- Anode resistor: a series resistor on each tube limits current to a few milliamperes, because a glow discharge is a negative resistance load and will otherwise run away and destroy itself
- Digit switching: a high voltage BCD driver such as the K155ID1 sinks the selected cathode
- Timekeeping: a DS3231 real time clock with a temperature compensated crystal holds a couple of parts per million
- Multiplexing: tubes are strobed faster than the eye integrates, so persistence of vision fills the gaps

What you end up with is display technology from 1955 sitting under a modern microcontroller, and the reason it still outclasses anything backlit is depth. Each numeral occupies its own physical distance from the glass, so the digits genuinely stack in three dimensions.

Full kits and build guides are linked in bio.

Screens imitate light. Nixies make it. (For reference the diy kit works on different principles, but og clocks function as above) 

#stemantics #nixietubes #diyelectronics #vintagetech #engineering

## Stats

- **Views:** 12,813
- **Likes:** 134
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- **Comments:** 2

## Tags

vintagetech, engineering, diyelectronics, nixietubes, stemantics

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