The TI CD4511B datasheet lists the lists the *minimum* high level output (at 5v VDD) of 4.1v but typical is 4.55v, maybe others are different?
https://www.ti.com/lit/ds/symlink/cd4511b.pdf At 4.55v the segment current on the IV-9 is going to be about 25ma. Typical IV-9 segment current is about 20ma I believe, so that would be a 25% overdrive. I've put up a drive voltage vs segment current table on my site, maybe it's useful to someone: http://www.neonixie.com/IV-9-6D-RR/#tech I settled with powering the tubes in my designs in one of two ways.. 5.0v direct with a recommended PWM of about 65% (the 165 (out of 255) value in the table) OR 5v through a regular silicon diode, dropping the voltage to about 4.2v at the tube and PWM that to 76%. Both result in a segment current of 20ma. Don't know if one or the other is better in regards to lifetime, I was not able to find any official sources of information. I experimented with driving them using a 3.3v regulator.. but at that voltage they were a bit dim. NOTE: The IV-9 datasheet does mention to avoid running the tubes at a frequency between 105 and 1000 Hz, presumably to avoid mechanical resonance. I elected to run them at 1600 Hz. I looked through some of my testing data.. at a segment current of 3mA the segments are visible, 2mA they are "barely visible" and at 1mA I noted them as not visible. Keeping the unlit segments warm with a slight current seems to make the most sense to me. It's all software on my clock so maybe an option for the next revision. That's all I know so far. Regards, -Moses On Saturday, March 4, 2023 at 5:52:05 AM UTC-8 [email protected] wrote: > Hi Chris, > > > > The numitrons are driven by a 4511 decoder, and according to their data > sheets the max. output at that voltage is 4.1 V, so that is well within > specification for the tube. Yes, I agree, lowering the voltage even further > should increase lifespan. > > > > Bill v > > > > *From:* [email protected] <[email protected]> *On Behalf > Of *Chris > *Sent:* Saturday, March 04, 2023 8:19 AM > *To:* neonixie-l <[email protected]> > *Subject:* [neonixie-l] Re: IV-9 numitron lifespan > > > > Hi, > > While i am not sure for the IV9 numitrons have a look at the DA2300 > lifetime expectancy, > > > > Basically reducing the voltage increases the life expectancy > exponentially. > > So i usually run my numitrons at 4.5V or lower and have had no issues so > far. > > On Friday, March 3, 2023 at 8:05:48 PM UTC+1 [email protected] wrote: > > I seem to recall there was some discussion on the life expectancy of IV-9 > numitrons some time ago. > > > > In 2015 I built a number of clocks with these tubes, and they started > failing last year. The clock in the picture is on my bench now, the three > good tubes were replaced in November last year. So today all 6 tubes will > be replaced. I have replaced all 6 tubes on a few other clocks also. One or > more segments will no longer light up, and I do not see any blackening of > the glass tube (The black you see in the picture is my permanent marker, s > I will not replace the wrong tube when I disconnect the power). > > > > The tubes are driven directly from a 4511 chip on a 5V power line. > > > > There does not seem to be any order in which they fail, so I do not have > the feeling that any of the tubes are significantly impacted by thermal > stresses from flashing on and off. I would say based on my experience with > them, the expected lifespan is about 7 years of continues use. > > > > Bill v > > -- > 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 on the web, visit > https://groups.google.com/d/msgid/neonixie-l/81b5b7e6-d476-4b83-9a8e-c9d6cc468db9n%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/81b5b7e6-d476-4b83-9a8e-c9d6cc468db9n%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 on the web, visit https://groups.google.com/d/msgid/neonixie-l/92508839-33de-4b2b-8603-e3e6cb686b29n%40googlegroups.com.
