Measuring the current is tricky if you are doing it while the dekatron is spinning (need a scope); a meter will only give an accurate reading if it's stationary. Even then, the apparent brightness as judged by your eye is not linear relative to current because there is a plateau effect where large current increases have small visible impact on the brightness. Only at the low-end is the brightness vs current effect most visible. So, if the current is in the right ballpark, your only other option is to experiment with the timing.
If you are using 200usec steps, and the pattern uses overlapping (best option in my opinion), it will take 60 steps for 1 full revolution. That works out to 2.5kHz, which is near the upper limit for most dekatrons. I think the A101 is rated at 1Khz, but I've never run mine anywhere near that. I would try running it at lower speeds to the point where the flickering just starts to appear. On Sunday, October 6, 2024 at 7:51:05 AM UTC-7 Martin Kaufmann wrote: > Have tried now with the series resistor (used a pot). but it does not > affect brightness. Also current stays between 280-300uA, regardless which > value the series resistor has. Did expect current to either rise or fall > when changing the resistor value (ohm's law), but it just stays the same. > funny. > > I have a feeling my "problem" is related to the hv supply, which is > probably better suited to charging a capacitor than supply a load. > > Have yet to try with reduced driving speed... > > On Sunday, October 6, 2024 at 9:08:01 AM UTC+2 Martin Kaufmann wrote: > >> Thank you very much for your explanations. >> >> The OG-4 type draws 400-450 uA according to specs. I'll try to see, if >> there is potential with optimizing the series resistor. >> >> As for the drive speed. Currently I use 200us - if my math is right, I am >> more in the range of 5000Hz with this (probably divided by two, due to the >> nature of my isr stepper routine). Maybe I have to reduce speed as much as >> possible without getting into "flickering" in order to max. out brightness. >> Gonna try this too. >> >> Alternative tubes or leds are not an option - it just matches perfectly >> with the in-4 nixies I will combine the dekatron with. I really love the >> optics here :-) >> I've seen this sort of dekatron-animation with clear bright glows on all >> of the cathodes - this tells me it should be feasible... >> >> On Sunday, October 6, 2024 at 6:17:19 AM UTC+2 gregebert wrote: >> >>> Brightness is a function of current; more current=more brightness, but >>> also causes more wear out of the tube. It's important to stay within >>> datasheet recommendations, otherwise your tube will fail prematurely. >>> Brightness is increased by increasing the high-voltage supply or reducing >>> the series resistor value, or a combination of the two. I have a single >>> A-101 dekatron in one of my clocks, and it's been running 27/7 for 11 years >>> now with no visible degradation. I think my supply voltage is around >>> +500VDC, and the series resistor is around 470K [sorry, that's from memory >>> from 2013...] >>> >>> Brightness is also a function of how much (or little) the pattern >>> changes. If you are trying to get a full-circle on a dekatron, it will need >>> to be spinning about 30 times/second to trick your eyes. There are 30 dots >>> per revolution on a dekatron, so that's around 900Hz. Since the individual >>> dots are only glowing 1/30 of the time for a full-circle pattern, they are >>> going to be noticeably dimmer than a stationary dot; you can see this in >>> your photos. >>> >>> If brightness is paramount, then you would be better off using 30 LEDs >>> (or 30 neon bulbs....) in a ring and drive them individually so they can be >>> on 100% of the time for max brightness. It's not as cool as a dekatron, but >>> it is brighter. >>> >>> On Saturday, October 5, 2024 at 2:21:25 PM UTC-7 Martin Kaufmann wrote: >>> >>>> https://threeneurons.wordpress.com/ - yes, this was/is my main info >>>> site regarding these tubes. being a noob, I did not fully understand >>>> everything though. Also cannot recall to have read something about >>>> controlling tube brightness, but I might have missed it and will check >>>> again. >>>> >>>> On Saturday, October 5, 2024 at 11:08:38 PM UTC+2 Mac Doktor wrote: >>>> >>>>> >>>>> On Oct 5, 2024, at 4:50 PM, Martin Kaufmann <[email protected]> wrote: >>>>> >>>>> maybe one of you who truly understands dekatrons, can explain to me or >>>>> give me a hint, >>>>> >>>>> >>>>> Just to be clear, have you seen/devoured this site? >>>>> >>>>> https://threeneurons.wordpress.com/ >>>>> >>>>> >>>>> I take it that Mike is one of leading lights in the Dekatron realm. >>>>> >>>>> >>>>> Terry Bowman, KA4HJH >>>>> "The Mac Doctor" >>>>> >>>>> https://www.astarcloseup.com >>>>> >>>>> "If only you could see what I've seen with your eyes."—Roy Batty, *Blade >>>>> Runner* >>>>> >>>>> -- 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/c8428bc1-33bc-444e-bd29-aa4d244db29en%40googlegroups.com.
