ESP32 nixie “four letter word” (alphanumeric display)

Following my 6 digit numitron clock using the ESP32-WROOM module (here), I wanted to use this experience combined with my high voltage power supply projects to build a full fledged, large size nixie tube display.

This project combines many aspects of embedded design into one product. Inspired by the modular design of the MOD-SIX clock (here), I planned my electronics package to be separated into 3 different modules; a power supply unit (PSU), tube driver unit (TDU), and a central processing unit (CPU). However, I did not want to simply “redo” the MOD-SIX using the Burroughs B7971 alphanumeric tubes. Without sacrificing alphanumeric capabilities by using regular numeric nixies, I found a tube which would suit my needs: the Telefunken ZM1350. It functions exactly the same way as a B7971, as it is a 14 segment cold cathode display. It has several advantages over the 7971; namely being much smaller and less fragile for a modest reduction in display size (40mm digit height for the ZM1350 vs. 63.5mm for the 7971). The ZM1350 also does not have an anode grid over the segment cathodes, in addition to an extra decimal point cathode which the 7971 does not have.

Without further adieu, I set about using the existing 10 watt power supply design I already had for the MOD-SIX. The tube driver unit and the CPU had to be designed specifically for this project.

Some notes on the ZM1350 TDU (Tube driver unit). In order to create a surface mount receptacle for the 0.8mm diameter pins of the ZM1350 with enough strength to hold the tubes and not rip pads off of the board, I used two different pin receptacles. The 0.8mm pins of the ZM1350 nest into mill-max part #‎6857-0-15-15-47-27-10-0, which then plug into harwin part #‎S9111-45R.

First and second revision hardware:

If anyone is interested in KiCad footprints for the unique ZM1350 mounting system, feel free to contact me through the “contact” tab on this site. More updates will come as software development and case design progresses.

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