I've found that the larger DR2000-type tubes do run stone cold, but the IV-9 and IV-16s will heat up a bit (warm to the touch) in continuous use. I've only made devices with a few digits - up to six. Sixteen could dissipate a reasonable amount of heat, but consider that there also must be a fair viewing area for that many tubes, even if there is a bezel with a thin lens, through which heat can escape. Twelve watts shouldn't be too bad at that size - perhaps 1" x 6" (25mm x 150mm) or so? especially if there are cooling vents somewhere in the bottom and top of the enclosure. ~~ Mark
On Saturday, May 9, 2026 at 12:09:57 AM UTC-7 newxito wrote: > To keep the segments warm, my plan was to use just PWM. Maybe it would be > easier to add just a bias resistor for each segment. On the other hand, > there are 128 segments, so it wouldn't be that simple after all. > To limit the current I will configure the TLC5921 to deliver 19mA on the > outputs. > For the 4.5V 3A power supply I've found the AP62301WU-7. It needs just a > few external components and is cheap, small and easy to solder. > > gregebert schrieb am Samstag, 9. Mai 2026 um 01:56:23 UTC+2: > >> I also recommend current-limiting so that you dont get surge-current on >> cold filaments. I put preheat hardware and software in place; during >> preheat, all segments get just enough current to make them warm, but not >> glowing. This reduces the thermal shock when turning them on as well as off. >> >> I dont have enough numitrons to generate any lifetime data, and I dont >> run those clocks very often...only to gawk at them every few months. Then >> back to standby. >> >> >> On Friday, May 8, 2026 at 9:02:34 AM UTC-7 newxito wrote: >> >>> Good point. I will add the thermal monitoring to the firmware. I will >>> use the same firmware as for the nixie calculators, I just have to add a >>> numitron display driver. >>> The idea is to also reuse the same case, which already has ventilation >>> slots at the top and bottom. >>> This is my first numitron project. I'm now designing a 3A 4.5V power >>> supply that will replace the HV PSU and a new driver board with 8 x >>> TLC5921. >>> I'll upload a thermal image once I've finished the project. >>> >> -- 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/645f0464-9d38-4351-af98-8d2c827226efn%40googlegroups.com.
