z5900 Nixie Tube - Two Anodes

Thread Starter

TheMobius40

Joined Sep 13, 2018
28
Hello there,

I am testing a few z5900 German-made nixie tubes, and they each have two anodes. Datasheet here.
I have tested them with each anode connected independently, and with both at the same time, and there is no noticeable difference (brightness, current draw, etc.). All digits light in all cases.
It seems to me like a redundancy in case one of them fails, but I don't know of any other tube that has this characteristic, so it seems unlikely.

Does anyone happen to know the purpose of the two anodes for this particular tube?
 

ebp

Joined Feb 8, 2018
2,332
I wonder if the intent might be for controlling brightness. If the anodes were switched you could use two resistors and get at least two probably fairly distinct brightness levels. You might get three levels by using different values for the two resistors.
 

Thread Starter

TheMobius40

Joined Sep 13, 2018
28
Z590 show two rows of cathodes.
Max.
It does have two rows of cathodes, but its not bi-quinary. Either of the anodes can light all digits independently.
The only difference between the z590 and z5900 is the color.
 

Thread Starter

TheMobius40

Joined Sep 13, 2018
28
I wonder if the intent might be for controlling brightness. If the anodes were switched you could use two resistors and get at least two probably fairly distinct brightness levels. You might get three levels by using different values for the two resistors.
I tried switching between 20K and 40K resistors (the highest and lowest possible while remaining in safe current range), and there is no noticeable difference that I can tell for sure. There might be a minuscule change, but it might be my eyes telling me what I want to see. Nothing worth trying to use.
 

Thread Starter

TheMobius40

Joined Sep 13, 2018
28
I was just keeping the current between 1 and 2mA, as the datasheet specifies.
There is a distinct brightness difference with a higher resistance; it began losing uniformity after about 100K. Current obviously drops pretty low with this resistance.
I was able to switch between the two brightness levels for each anode, and it worked fine.

This is the only nixie I've found that has this "feature" without being bi-quinary. Curious.

I suppose that answers my initial question. Thank you everyone.
 
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