Joshua Coleman's Nixie Tube Art Project Makes Clever Use of Gazotron's Symbolic IN-7 Tubes
Originally designed for multimeters and other measurement tools, IN-7 tubes are in plentiful supply — as this "MAKE" demonstrates.
Maker Joshua Coleman has been diving into the world of Nixie tubes, but what he's created isn't your common or garden desktop clock — making use, instead, of non-numeric tubes all too often discarded by Nixie enthusiasts.
"[This is] a simple build that I did which cleverly uses the plentiful IN-7 symbolic Nixie tube to make something a little more interesting," Coleman explains of his creation. "These tubes are plentiful because most people just want number Nixie tubes for clocks and other projects that require numeric digits. However, with some clever rearrangement of one of the symbols we can eke out the word 'MAKE' from these tubes — and as I facility a maker space, I felt it fitting that this word could be wrangled out of some old tubes meant for other purposes."
Makers the world over will be familiar with the classic Nixie tube, a display technology dating back to the 1950s in which a vacuum tube holds a wire-mesh anode connected to multiple stacked cathodes. By running power through only one of the cathodes, you can pick which of the stack illuminates in a cheery glow — and, in most cases, that's the numbers zero through nine.
The tubes Coleman has been using, though, are less popular: rather than the more broadly applicable numerical digits, the Gazotron IN-7 tube was designed for use in multimeters and other measurement tools — offering symbols, rather than digits. With the stacked cathodes shaped to deliver the symbols +, -, Ω, к, П, m, M, A, V, they're understandably less popular than the numeric versions, but that doesn't mean they can be used for purposes the manufacturer had never intended.
Coleman's hack: uses the M, A, к, and m symbols, but turning the final tube 90 degrees — turning the milli symbol into a somewhat stylized capital E. All together, the tubes now spell MAKE, housed in a chassis of laser-cut acrylic and driven by a custom home-etched PCB with a 555 timer and adjustable pulse speed via a potentiometer.
The project is detailed in full in the video above and on Coleman's YouTube channel.