On Wednesday, February 21, 2018 at 1:39:24 PM UTC, Terry Kennedy wrote: > I have a pair of Numimini clocks (from Jon Ellis here) with IV-9 tubes >> which have been running continously here for over 8 years with no issues. >> They are powered by the host PCs' USB ports, so there is some magic >> involved in staying under the available 500mA available when driving the >> filaments. >> >
Nice to hear they're still running well! Having liberated 50-odd Numiminis into the wild over the years, I'd say that your experience seems to be widely shared. I don't recall any reports of either IV-9 or IV-16 failing in use, though a few tubes have suffered terminal mechanical trauma (cats, office cleaners etc). As we've discussed here a few times, the lifetime figures quoted on the datasheets for the Russian indicator tubes (nixie and numitron at least) seem to be pretty conservative. Not sure I'd claim much magic in the design - though might confess to having given it a little thought :) It uses a pair of A6279 LED drivers which have constant current sink outputs to help with the filament inrush current issue. Total current management is achieved by having the clock operate in direct drive mode if it's being powered from a wall wart USB charger or as a 2x2 multiplex when being powered from a standard USB port. The PIC that runs the show can tell what the power source is and configures the display mode automatically (can also be fixed manually if you like). It also actively controls the sink current setting on the A6279s, and that's used to govern overall display brightness in response to user preference or ambient light. In practice I think the design results in the tubes almost always being significantly under-driven, except maybe if you deliberately max out brightness with a wall wart power supply. Jon. -- 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 neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/bdc0b6c4-78ff-434f-b276-3a38ac846b6a%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
