If you mis-spent your teenage years fishing broken televisions from dumpsters and either robbing them for parts or fixing them for the ability to watch The A Team upstairs rather than in the living room as I did, then it’s possible that you too will have developed a keen interest in analogue television technology. You’ll know your front porch from your blanking interval and your colour burst, you might say.

There was one piece of television technology that evaded a 1980s dumpster-diver, no 625-line PAL set from the 1970s was ever going to come close to the fascination of the earliest TV sets. Because instead of a CRT and its associated electronics, they featured a spinning disk with a spiral pattern of holes. These mechanical TV systems were quickly superseded in the 1930s by all-electronic systems, so of the very few sets manufactured only a fraction have survived the intervening decades.

The spinning disk in a mechanical TV is referred to as a Nipkow disk, after its inventor, [Paul Gottlieb Nipkow]. [Nipkow] conceived and patented the idea of a spinning disk with a spiral of holes to dissect an image sequentially into a series of lines in the 1880s, but without the benefit of the electronic amplification that would come a few decades later was unable to produce a viable system to demonstrate it. It would be in the 1920s before [John Logie Baird] would develop the first working television system using [Nipkow]’s invention.

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