I'm speculating that in order to get the higher current for multiplexed operation, the increased voltage was enough to coax a bondwire into glowing. I have a few 5031 nixies that are so worn-out that only the bondwires glow.
On Monday, October 30, 2023 at 1:43:57 PM UTC-7 Greg P wrote: > Interesting. > > On Monday, October 30, 2023 at 2:27:50 PM UTC-4 Craig Garnett wrote: > >> The directly driven tube is just 2mA and that doesn't light the pins. >> If I swap the tubes then it stays with the multiplexed tube. >> >> On Monday, 30 October 2023 at 14:58:31 UTC Greg P wrote: >> >>> How much current are you using in a directly driven tube? I’ve had the >>> same issue with the pins lighting up with as little as 1mA on the Z570M >>> tubes. >>> >>> >>> On Monday, October 30, 2023 at 10:31:57 AM UTC-4 Craig Garnett wrote: >>> >>>> Increasing the HT gave me 10mA and looks pretty good but is this an >>>> issue in the photo? >>>> It only occurs in the multiplexed tube. >>>> >>>> Thanks >>>> Craig >>>> >>>> On Friday, 27 October 2023 at 18:13:19 UTC+1 Craig Garnett wrote: >>>> >>>>> Thanks gregebert, >>>>> I'll have a play with the HT voltage and report back. >>>>> >>>>> Craig >>>>> >>>>> On Friday, 27 October 2023 at 16:33:12 UTC+1 gregebert wrote: >>>>> >>>>>> You can run nixie tubes at much higher voltages if you wish, it does >>>>>> no harm as long as you increase the series resistor to keep the current >>>>>> within spec. For example, my first nixie clock runs the B5092 tubes from >>>>>> a >>>>>> +340V supply, and I used a larger resistor (75K I think) to get the >>>>>> optimal >>>>>> 2.2mA current. Running at higher voltage gives you more design margin, >>>>>> but >>>>>> it does waste more energy as heat. Generally my HV supplies run between >>>>>> +200 and +220VDC; seems like every clock I make ends-up with a different >>>>>> power supply design. So far, I've designed and built nixie clocks with >>>>>> B5092, B6091, B7971, IN-18, and RZ568m tubes. >>>>>> >>>>>> I would bump your supply up to +200V, and adjust the resistor to get >>>>>> 8mA of peak current (6:1 multiplexing). That will give plenty of voltage >>>>>> margin as the tubes age. From the photo, 8mA looks nice. I recommend >>>>>> that >>>>>> you view your tube as you vary the supply voltage to get currents >>>>>> between >>>>>> 5mA and 12mA just so you can see the effect of current on brightness. >>>>>> You >>>>>> should see that once the tube is lit "normally", increasing the current >>>>>> doesn't make as much of a change visually. >>>>>> >>>>>> I dont run my tubes multiplexed for a variety of reasons. >>>>>> >>>>>> On Friday, October 27, 2023 at 1:38:06 AM UTC-7 Craig Garnett wrote: >>>>>> >>>>>>> Thanks gregebert >>>>>>> >>>>>>> My HT is a 12V module and is adjustable but the tube spec says 170V >>>>>>> so I left it at that. >>>>>>> Are you saying that it's safe to increase the HT to get maybe 10mA? >>>>>>> >>>>>>> Craig >>>>>>> >>>>>>> On Friday, 27 October 2023 at 05:06:34 UTC+1 gregebert wrote: >>>>>>> >>>>>>>> My concern is that over time as the tubes age your HV supply >>>>>>>> voltage might be too low to ensure proper ionization. If it's not >>>>>>>> adjustable, you can boost it with a series DC supply such as a >>>>>>>> wall-wart >>>>>>>> transformer or a small isolated DCDC converter. Anything from +12 to >>>>>>>> +24 >>>>>>>> should work fine, and the current is pretty low (12mA). >>>>>>>> >>>>>>>> Once you get the HV supply resolved, you will be able to get more >>>>>>>> current thru the tubes. BUT......you may want to stay with 8mA. From >>>>>>>> the >>>>>>>> photo, the tubes glow nicely. Tube wearout is an exponential function >>>>>>>> of >>>>>>>> current, so staying at the lower currents is better for longer >>>>>>>> lifetime. At >>>>>>>> some point, the current could be too low and you might see cathode >>>>>>>> poisoning, but that's reversible. My gut feeling is that 8mA of pulsed >>>>>>>> current should be fine. >>>>>>>> >>>>>>>> So, are you using rectified AC-mains as your DC supply ? No >>>>>>>> worries, I've done that on several clocks and it can be done safely >>>>>>>> with >>>>>>>> proper circuit design. >>>>>>>> >>>>>>>> On Thursday, October 26, 2023 at 7:28:18 AM UTC-7 Craig Garnett >>>>>>>> wrote: >>>>>>>> >>>>>>>>> The ongoing project of mine is coming on nicely but I need some >>>>>>>>> reassurance with the way I'm driving the Z570s. >>>>>>>>> >>>>>>>>> There are two banks of 6 multiplexed tubes, from what I see from >>>>>>>>> the datasheet these should run at 2ma static or up to 12ma as a 1 in >>>>>>>>> 6 >>>>>>>>> multiplex but that is using google to translate from the datasheet's >>>>>>>>> German. >>>>>>>>> >>>>>>>>> The problem is that even with a 1K anode resistor I can't quite >>>>>>>>> get 8mA from a 170V supply. >>>>>>>>> The photo shows two tubes, the left is static at 2mA and the right >>>>>>>>> is multiplexed at just under 8mA with a 1mS on time from a 170V >>>>>>>>> supply and >>>>>>>>> 1K anode resistor.. >>>>>>>>> >>>>>>>>> Is this ok or could I do it a better way? >>>>>>>>> >>>>>>>>> Thanks >>>>>>>>> Craig >>>>>>>>> >>>>>>>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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