On 3/8/11 11:36 PM, Jarek wrote:
I've received my nixie power supply from tayloredge, and I set up a
small circuit to test what value anode current limiting resistor I
need. I set the voltage to 180v, and found that the optimal current
for my IN-14 tubes (which is 2.5mA) is achieved at 14k ohms. I
soldered up my full circuit, which includes 15 IN-14 tubes, with a 14k
resistor at each anode, 15 in all. When I plugged in the same power
supply, my ammeter saw a 40mA draw, which equates to 2.66 mA per tube.
Would a +0.16mA increase over optimal current harm the tubes? I'm a
little paranoid due to the scope and expense of this project, and I
would like the tubes to last as long as possible. Each tube is driven
directly, no multiplexing, with a standard Russian 74141 clone chip
per tube.
There is a natural variation in the sustaining voltage of the tubes,
both from tube to tube and between cathodes in the same tube.
A difference of 0.16mA is on the order of 5%, which is nothing to worry
about. I suspect that if you made the tubes display a different 15
digits, you'd see a different current draw.
--
David Forbes, Tucson AZ
http://www.cathodecorner.com/
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