If you direct drive them @ 12mA and you want to have them the same brightness when multiplexed, you will need to increase the current to 36mA (as they are only on for 1/3 of the time). Which means 12mA for 2 tubes at all times, 6mA per tube @ 33% duty = 2mA average current per tube.
Adam is right, you cannot measure that accurately with a DC multimeter. I even tried with a Fluke true RMS multimeter and that gives rubbish readings as well. Michel On Mar 5, 9:36 am, Imbanon <imba.a...@gmail.com> wrote: > I direct drived all 6 of them, delivering 12mA without a problem. > Tested only up to 15mA. Didn't want to go further.. > > Thanks again > > On Mar 4, 11:29 pm, Adam Jacobs <a...@jacobs.us> wrote: > > > > > > > > > Disable the multiplexing, so that only 2 nixies are lit (and those lit > > at 100% duty cycle). THEN measure the current draw. You will not be able > > to accurately measure the peak current draw of a multiplexed nixie with > > a multimeter. . and YES, you definitely need a current limiting resistor > > or you will break your nixies. > > > -Adam > > > On 3/4/2012 2:26 PM, Imbanon wrote: > > > > Hi all! > > > > I have a question about multiplexed nixies (2x3 - 2 turned on at a > > > time). > > > First of all.. I cannot get a 2mA (or at least I think so) on my > > > IN-14s. It lead me to completely remove the anode resistor! Can a > > > nixie tube be harmed if it does not have an anode resistor? Without > > > any resistors, I can get up to 1.8mA measured with my multimeter in DC > > > mode. > > > > So I figured to try to calculate it. I think that the multimeter in DC > > > mode shows average readings (that's true, right?). So with the formula > > > that the average current equals Vpp*T1/T, in which T1=4ma, T=13.6 and > > > Iavg=1.8mA, Vpp equals 6.12mA. > > > Is that really possible? I would say that the current would be much > > > higher. My 555 supply is capable to deliver at least 15mA at 200V > > > (tested). > > > So with Vpp I calculated that by the RMS formula Irms=Vpp*sqrt(T1/T), > > > RMS current is 3.32mA, which is impossible by my judgement of > > > brightness. > > > > I will hopefully get my hands on a scope this week to check out the > > > real peak current. But is there anything I can do before, or even if I > > > get a chance to use a scope? > > > > Many thanks! -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
