The circuit is simple, the board was certainly hand drawn and it has a comfortable 25+25 pins 0.1" pitch edge connector.
I chose to reverse engineer connections with my picture-over-picture method rather than probing with the continuity tester:
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| Front, back and numbered neon lamps. |
Each lamp leg was mapped to a connector pin and everything went into a final table that looks like this:
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| The result of reverse-engineering the PCB. Click to zoom-in. |
Two lamps ("q" and "1") go directly to the connector, probably because who drew the PCB didn't have time to look for a better routing layout. I think their "anodes" (neon lamps don't have proper anode and cathode) were tied to another "anode" pin, or at least that's what I did when looking for a connection layout that makes sense. In the end I came up with four groups almost ten of lamps, marked as A_ in the table. Lamp cathodes are connected to K_ pins.
Wait a minute. 4 anodes, 10 cathodes: that's the layout of a 4-digit multiplexed Nixie clock! I can drive the blinkenlights gizmo with one of my Nixie clock boards and a bit of custom firmware! How cool is that? It will need a heavier multiplexing strategy than 1:4 of a clock because in each "configuration" there can be more lamps "ON" for each anode. And you cannot have two lamps in parallel "ON" at once for some physics of Neon gas :)
Some cathodes "cross" just one anode, others three or four anodes. Well, that adds some extra randomness to the light show.
