Blue Dot

[bcage]

Has anyone else experienced the blue dot phenomenon?  I just assembled my Arduinix and attached it to one nixie IN-18 tube for a test.  I used the test code for a one bulb setup from this site.  The nixie works correctly, but there is a blue dot that appears when the 1 digit is displayed.  A search on the net turned up a number of posts on this problem, but, to be honest, I don't really understand the issue.  The consensus seems to point the finger at the circuity, not the tube itself.  If that is the case, how would this be resolved?

Any insight would be appreciated.

[linux-works]

I have seen posts that talk about the russian driver chip having some problems.  it seems there are good and not so good driver chips (from what I can tell, the ground that they give is not very low and so there is not a 'strong' circuit for the tube.  not sure why the 1 numeral is the issue but I have also read about that.

do you see this blue dot when you manually connect a cathode to ground (not using chips; just literally powering the tube from the 170v supply, connecting its anode to + and the 1-cathode to gnd?

[Risen]

My understanding is that the 74141 (and Russian equivalent) which the ArduiNix uses is not suitable for driving IN-18s. You might find some tubes and some chips which work together, but this is mostly by coincidence and not by design. Unfortunately the fix is to use a different driver circuit than what the ArduiNix provides.

[bcage]

Ahhh... I hope that is not the case.  I will move on with the Arduinix, IN-18, blue dot (unfortunately) on the digit 1 combination for my first clock build.  Maybe I can get smarter and do a version 2 that is better.  Can you help point me to sources of information?