I've now tried with slower frequency, but to no avail - brightness decreases with every additional lit cathode. Gonna try a different power supply next.
On Sunday, October 6, 2024 at 10:10:11 PM UTC+2 gregebert wrote: > 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. 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