[neonixie-l] Re: VFD filament resistance when hot/cold?
For my VFD filaments, I've settled on using a power supply module with a configurable soft-start time. I've set it to something huge, like 10 seconds, to try to limit the inrush current. -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/8fd8b86d-7254-4a08-95c5-06a4566db269o%40googlegroups.com.
Re: [neonixie-l] Some neonixie-l changes...
Movember is a good cause, I've done a few of those campaigns myself and grown a pretty outrageous handlebar much to the horror of all those around me... :) Only I have the photoLOL. But for a couple of CD47's, I'd post it here ha ha!! Cheers, (Pharma) Nick On Tue, Jul 14, 2020 at 8:16 PM Nick wrote: > Argh! That dodgy, 70s porn star moustache !! > > I need to explain. Really, I do... > > It started during a "Movember" men's health fundraising effort - for those > that don't know, Movember is where (mostly) guys try to grow an outrageous > moustache during the month of November - the wilder and more unlikely the > better - mine ended up like Zapata's. All for charity... > > I was working for a financial services company in London and they agreed > to double the money if you got your photo on an official document... > driving licence and passport in my case... It was worth a lot of money for > charity - many 1000s of GBP... > > Thankfully, sanity was restored and it's long gone now - even it's absence > caused problems. Passports last 10 years here and the last few years I've > been based in the Gulf (UAE) and doing a lot of travelling. Every border I > crossed they had problems with the passport photo vs. reality. It was a > silly idea. > > -- > 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 view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/8a88b83e-ffd4-445c-adaa-63b69a05d2f1o%40googlegroups.com > . > -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CAOX%2BRHLWoLziUJcfbGsGw8e3Syz5p0-GxrbjSy6DmXJtec8X2w%40mail.gmail.com.
Re: [neonixie-l] NIMO
I‘m using Eagle to layout. It takes time for me to feel comfortable with it. And Fusion360. -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/76cb4ec4-1d3f-4d8b-a406-deb523a6cd65o%40googlegroups.com.
[neonixie-l] Re: VFD filament resistance when hot/cold?
Absolutely! The difference between operating and inrush-current is a leading cause of burnout. If you recall, incandescent room lights generally fail when you turn them on. It's the same mechanism. If you dont plan on power-cycling the filaments very often, you can just leave it as is and replace tubes every few years. You will probably have phosphor degradation before the filaments burn-out. If you like doing reliable designs, you can limit the inrush current with a series resistor, and driving from a higher voltage. Or you could use a triac to control the filament transformer, and gradually increase the proportion of the AC-cycle to soft-start the filaments. Here's a table of filament resistance vs current, once temperature had stabilized, from a BAP31 NIMO tube: [image: ScreenHunter_28 Jul. 15 07.16.jpg] - I faced a similar issue when designing my NIMO -tube clock. NIMO tubes are very rare, so every means must be incorporated to protect them. I chose to drive the filaments from a higher supply voltage and some series resistance. In my case, I was able to reduce the peak current from 400mA to 250mA, while keeping the operating current at 180mA. The datasheet specifies 200mA. In addition, I have a 250mA fuse for each tube, and hardware+software to check each filament, fuse, and dropping resistor. The last part is what algorithm should I use for shutting-down the filaments ? Leaving them on continuously will eventually lead to burnout, but turning them on/off too frequently will also cause wearout. Right now I'm using a 30-hour timeout on my IR motion sensor, so if nobody enters the room for just over a day, they shut down. Furthermore, it takes a bit of extra movement to turn them on so if you tiptoe into the room, they stay off. On Wednesday, July 15, 2020 at 6:20:16 AM UTC-7 Jasper C. wrote: > I'm working on a project using some IV-17 tubes, and I cam across > something I need advice on. The datasheets I've found say that the > filament current is 47 mA at 2.4 Vac, so an effective resistance of about > 51 Ohms. But on 3 tubes I've measured, they're all about 20 Ohms. Does > the filament resistance change when hot? Because that seems like a huge > difference... > -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/cc559484-d502-4866-81f0-88566758d52dn%40googlegroups.com.
[neonixie-l] VFD filament resistance when hot/cold?
I'm working on a project using some IV-17 tubes, and I cam across something I need advice on. The datasheets I've found say that the filament current is 47 mA at 2.4 Vac, so an effective resistance of about 51 Ohms. But on 3 tubes I've measured, they're all about 20 Ohms. Does the filament resistance change when hot? Because that seems like a huge difference... -- 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/1aa2a39c-df1e-462b-b271-79d8bebf796co%40googlegroups.com.
