Hey Mark, thanks for this info - a useful data point! I have a couple of these incandescent displays, but was always a bit wary of driving them directly. With all that said, keeping the filaments warm is definitely a good idea.
-Peter On Wednesday, April 29, 2026 at 2:32:10 PM UTC-7 Mark Moulding wrote: > For me anyway, the jury is *not* out on driving Numitrons (or Russian > equivalents) directly from TTL. In my case, I've made many clocks directly > driving the filaments from 74HCT595s, with precisely zero failures of > either the tubes or the drivers. On my newer devices I use PWM to control > the brightness, andalso keep the filaments warmed to just below visibility > when off, but I didn't do that at first, and a couple of those 15-year-old > units are still working just fine. > > This is true with a variety of tubes, too; I've used a lot of the Russian > IV-9s and IV-16s, some DTF104Bs, and some of the Aurora/Apollo flatpack > devices. I fully realize that the '595s are operating a bit out of spec, > but they stay cool during operation, even in less than ideal conditions > (110 degree heat at BurningMan, for example). > ~~ > Mark > > On Sunday, April 26, 2026 at 7:38:51 AM UTC-7 Mitch wrote: > >> I believe that I searched those archives. Thanks for the suggestion. I'll >> try again. >> >> On Saturday, April 25, 2026 at 1:57:01 PM UTC-4 Peter Csaszar wrote: >> >>> Well, maybe you'll just have to design it from scratch yourself. :-) The >>> jury is still out though whether the Numitorns can be driven from a regular >>> TTL (or LSTTL) output. One opinion is that they can, as long as there is a >>> diode in series with the Common, to lower the voltage on the filaments a >>> bit. Another concern is the inrush current when a cold filament is lit up, >>> jeopardizing the output driver of the IC - but based on some accounts, it >>> is not a real problem. >>> >>> On Saturday, April 25, 2026 at 9:32:18 AM UTC-7 Instrument Resources of >>> America wrote: >>> >>>> Just a wild guess on my part, due to the topic, and the year, but could >>>> it have been a Pop Tronics (Popular Electronics) article? >>>> >>>> Ira >>>> >>>> >>>> >>>> On 4/25/2026 6:07 AM, Mitch wrote: >>>> >>>> Around 1973 I build a clock from what I think was a magazine article. >>>> I've been looking for that article for years. I've searched archives with >>>> no luck. Here is the description: >>>> >>>> The clock was point to point wired on two stacked pieces of breadboard, >>>> around five inches square each. It included two incandescent seven segment >>>> displays on the top board, and was built with 7400 series ICs. It flashed >>>> hours, minutes, and seconds. >>>> >>>> Does anyone remember this project? I may have asked this question years >>>> ago. Thanks in advance. Mitch >>>> >>>> -- >>>> 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 view this discussion, visit >>>> https://groups.google.com/d/msgid/neonixie-l/ba633cd5-7f1e-4877-83a3-541112213122n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/neonixie-l/ba633cd5-7f1e-4877-83a3-541112213122n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>>> -- 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 view this discussion, visit https://groups.google.com/d/msgid/neonixie-l/71ac0e41-aee7-48f0-9c19-2167d07b2b3fn%40googlegroups.com.
