This is a current regulator circuit. It's pretty much the same as the one I use in my Nixie watches. The voltage developed across R1+R2 due to anode current serves to reduce the forward bias of the active anode transistor.
It's tricky, but not that tricky. On Tue, Jun 11, 2019, 2:11 PM Dekatron42 <[email protected]> wrote: > I've seen similar circuits when the Nixies have been driven from digital > clock ic's like the MM5309-series but then the Nixies have had separate > anode resistors too. > > /Martin > > On Tuesday, 11 June 2019 22:45:22 UTC+2, Paul Andrews wrote: >> >> I just came across this: http://www.glowbug.nl/neon/944125938_2356.gif >> (which seems to be an excerpt from >> https://archive.org/details/ElectronicCircuitsManual/page/n209) and >> would be interested in a critique of it from people who know more than I do >> about electronics - which is just about everyone here! >> >> The cathode controls are pretty standard fare for multiplexed tubes - >> including clamping the off cathodes to 75V (it is low enough to stop them >> acting as anodes, but high enough that they won't glow). I'm more >> interested in the anode controls. In particular: >> >> >> - Using capacitors to de-couple the 5V signal from the 200V rail (I >> assume)? >> - Tying the collector of the transistors to 110V, presumably to keep >> the voltage across the transistor within its limits, though I'm not sure >> what actual voltage would be present across them, because: >> - The anode resistor, which is shared by all anodes here, apparently >> varies from 180 to 300 Ohms. Is that a misprint? Can it be that low >> because >> of the multiplexing? Or is there something else going on here. >> >> Naturally now that I've seen it, I want to build it. Like I don't have >> enough projects going on. >> >> -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/ab43bb42-40ad-4ca4-a510-e594a043cebd%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/ab43bb42-40ad-4ca4-a510-e594a043cebd%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAPbqtveEQt%2BbV%2BjgykpuU5k0fNXRr_J8V-T_pcvnS_JeN5FvEw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
