Have now tried with a proper power supply, which does not sag voltage under load - does not make any difference. Seems, I've to live with the current reduced brightness...
On Thursday, October 10, 2024 at 10:34:00 AM UTC+2 Martin Kaufmann wrote: > 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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