> On Mar 8, 2026, at 5:18 PM, Holm Tiffe via cctalk <[email protected]> > wrote:
> <snip> > > ..so I have an working ring counter here next to me on a breadboard. :-) > > There is still an MPSA42 used as an pulse former in the clock circuit > that I want to change agains a trigger tube. I need an Ide of an circuit > that gets triggered on approx. 30-40V and outputs an rectangle pulse of > lets say 60V and 10-30µs duration to properly trigger the ring counter, > using possibly only one trigger tube. > I think no one knows that for now..but I'm very grateful for links > to older literature on this topic. > approximately in 2000 I'm parted out old hp tube counters, the displays > where "thermometer Displays using 10 pcs. of neon lamps, one for each > number. The counters used 4 12at7 type "digital" tubes (don't remember > the exact type for now) with biquinary output to the neon lamps. > Later hp counter modules used the very same schematics and the neons and > one hybrid photoresistor module in front of the neons as decoder to > drive nixie tubes. I've tried it already in the past with the neon bulb > ring counters.. a cheap photoresistor in a balc schrink tube that was > put onto the neon lamp can switch a nixie..it works flawlessly. > Tried this on the TX4b .. works too. :-) > ..other schematics ad an additional trogger tube for each nixie > cathode..the effort pretty much explodes... > > Hope someone can help with some hints or links. > > Regards, > Holm Hello Holm, I very much recall when Friedhelm completed his clock. Ironically, I was building my own version in parallel initially unaware of his project. For mine, I used Beckman modules which I modified for proper roll-over, and drilled out the “thermometer” indicator fronts to mount CdS cells for the Nixies. The timebase was a dekatron “Phantastron” circuit operating at 1 PPS. Black crinkle paint and IBM toggles with proper trim nuts completed the package. A slightly lower power bill, but not by much, haha. Here’s a 20+ year old photo. https://linearlook.com/eldocountry/projects/tubeclock/tube1lrg.jpg I have considered using neons in a ring circuit for a sequencer in my home-brew relay computer, but will probably go a different direction. Some folks have had success, but it requires much binning to get the desired characteristics for reliable operation. You were curious about links, I highly recommend this one: https://www.worldradiohistory.com/Archive-Catalogs/Suppliers/GHI/GE-Glow-lamp-manual-Theory-Circuits-Ratings-2nd-Edition-1965-118-pages.pdf Best Regards, Cory Heisterkamp
