Nixie calculator display

[Paul Andrews]

I have had a Canon X61884803 calculator display board for some time and I am in the process of trying to use this directly rather than pull the tubes from it. I figured out the basic circuit for it and put together a lash-up to drive it. Naturally it is multiplexed and LTSpice shows that 120Hz is a likely frequency.

I subsequently found an actual circuit diagram, for a calculator that uses this, here: http://madrona.ca/e/eec/calcs/Monroe650.html and it was interesting to see the voltages being used. I haven't tried to reproduce those voltages, instead driving it with a fairly standard set of 0V GND, 200V for VH-1, 100V for VH-2 (cathode pullup) and 12V 'logic level' input to the cathode transistor base resistor, though I have tried 8V through 20V for this.

I have only wired up a few of the connections to show I am on the right path with this, but now I am trying to figure out the ghosting. With that in mind, does anyone have the specs for the TMC1764 shown in the circuit diagram? Or, if anyone has access to a calculator that uses this display board, I would be interested to know the voltages on the outputs of this chip and perhaps even the timings?

It could also be that I need to actually wire all the connections up and see how it looks...

Thanks.

[Dekatron42]

Have you asked Brent Hilpert who owns the site you linked too if he has the datasheets? He has been very helpsome when i have asked him about other equipment with dekatrons and the E1Ts.

/Martin

[Paul Andrews]

On Friday, July 17, 2020 at 12:44:26 PM UTC-4, Dekatron42 wrote:
> Have you asked Brent Hilpert who owns the site you linked too if he has the datasheets? He has been very helpsome when i have asked him about other equipment with dekatrons and the E1Ts.
>
>
> /Martin

Hi Martin,

Yes - I sent him an email. Have not received a reply yet, but it is comforting to know that he is still active.

[David Forbes]

Ghosting is usually caused by changing the cathode value too soon after turning off the anode at the end of the display time for that digit. Try waiting a millisecond with all anodes off before writing the next cathode value.

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