I use a mains-powered 2.5VAC center-tapped transformer for my NIMO clock,
and apply a DC bias to the center-tap. Basically the same as your approach,
but not running at 100kHz. The DC bias comes from a DAC (with an OP-amp
buffer), so I can use software to control the offset, rather than a pot.
I wanted to try to avoid having a AC line in my design if possible. I did
have to break out my old ECE notes, and I designed a different filter.
Turns out my original RC filter requires a much larger resistor to limit
the primary side current, but that raises input resistance too high for my
I'm playing around a bit more with some active filter designs so it won't
be load dependent, but 100khz seems a bit high for this application. Going
a lower frequency would require I select a different/larger transformer
since my current would be too high.
On Saturday, 15 April 2023 at 03:26:46
I agree 100kHz seems high, but I don't see any downside if you can drive
that OK. I also see no need for a filter : the only effect I can imagine is
either too low (certainly not at 100k) or possibly a beat frequency with
the multiplexing which i'd avoid carefully (or zero beat i.e. in sync, but
It is OK now, I got help, Thanks a lot !!!
Le samedi 15 avril 2023 à 19:23:29 UTC+2, Benoit Tourret a écrit :
> OK, so I know no one will ever have these tubes. The seller changes the
> name of the tubes, (calling them a 7-segment device, that's perfectly
> true...) but I can't get them, ebay
OK, so I know no one will ever have these tubes. The seller changes the
name of the tubes, (calling them a 7-segment device, that's perfectly
true...) but I can't get them, ebay says it's not allowed to sell in
France...
The seller is a little upset and gave it up. I can understand, he lost his
I uploaded a draft of the calculator manual. This will be the functionality
of the first public firmware release... still work in progress...
https://github.com/axtar/14-digits-nixie-calculator/blob/main/Docs/14-digit%20Nixie%20Calculator%20Manual.pdf
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