ZM1370

This is a very rare planar neon display tube made by Telefunken. It is a 15 segment display that they called a ‘Varisymbol’. The only data sheet that even mentions this model does not contain much information about it (such as the pin geometry and current requirements for each segment). For this display I used values of 1/4 those for the ZM1350, my reasoning being that the segments were half the length and probably half the width. It looks about right.

An interesting thing about these displays is that the anode is a transparent layer of tin oxide deposited on the inside of the glass. Apart from giving an uninterrupted view of the segments, it also causes some interesting colors to appear because of selective refraction/reflection when lit just right by incident light

This is the most complete data sheet I can find:

ZM1350

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