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!
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