You should calculate the anode resistor you need for one segment. Use that, then connect all the cathodes to ground. I have done this many times accidentally. Now the hand waving part: Imagine the connection between the anode and cathode is a resistor and you connect all of the cathodes together - you are putting all of those resistors in parallel. You are limiting the current on each one to 2.25mA, so you are pumping 22.5mA through the one tube. I get that to be about 2W - (230-140)*0.0225.
On Wednesday, March 31, 2021 at 4:11:49 PM UTC-4 gregebert wrote: > Very interesting; thanks for posting. > > You might want to try successive numbers of lit cathodes, say 01, then > 012, then 0123, etc and see how the current increases, and also see if it > changes over time due to heating. > > I dont recall seeing this behavior with segmented tubes, like the 7971. In > fact, on my clock I have a current regulator on each cathode, and another > one for the anode, for every tube.....that works out to 128 current > regulators on that clock. > > On Wednesday, March 31, 2021 at 12:18:08 PM UTC-7 Bill van Dijk wrote: > >> Just a guess, but I think by lighting them all up you get some kind of >> “super ionization” in the tube, which could then increase the current and >> heat dissipation. >> >> >> >> Bill >> >> >> >> *From:* [email protected] [mailto:[email protected]] *On >> Behalf Of *Yohan Park >> *Sent:* Wednesday, March 31, 2021 3:15 PM >> *To:* neonixie-l <[email protected]> >> *Subject:* [neonixie-l] Lighting all digits at the same time: Why does >> this happen? >> >> >> >> I have a few Chinese QS30-1 tubes lying around which don't have much >> value for me and was wondering how it would look to have all digits lit at >> the same time. >> So I looked up the specs which say 170V and 2.25mA >> So I calculated the needed resistor to have it hooked up to 230V which is >> a little below 27K >> I then connected a 27K resistor to one cathode and it lit perfectly fine >> (230V AC so the anode also glows). >> So I then connected 10x 27K resistors to all the cathodes and plugged it >> in. >> Holy Moly! The thing lit up like crazy and was drawing over 9 Watts and >> was getting VERY hot. So I turned it off again after a few seconds. >> Can anyone tell why it's behaving like that? >> >> -- >> 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/bffb114c-9810-4d65-8e98-ee13f6c860fcn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/neonixie-l/bffb114c-9810-4d65-8e98-ee13f6c860fcn%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/a507adb6-6ea1-4c4f-b5b5-40b3fdc568a7n%40googlegroups.com.
