Nixie Tube Trouble

[Dman777]

Well, I guess I have really bad luck. My clock is only like 3 months old. 

What is weird is that this issue, for this particle tube, is random. It's not specific to just some digits. Sometimes it goes away and sometimes it comes back....doesn't matter which digit. 

Is this the tube itself or the clock circuitry causing this?

[gregebert]

My first guess is a bad tube; I cant tell from the picture if they are socketed vs. soldered. If they are socketed, try swapping tubes.

Second guess is the high-voltage power supply is just a wee bit low. Not all tubes ionize at the same voltage. Try measuring it; should be

180V or more.

If your clock is multiplexed, it's possible though unlikely the anode driver for that digit is weak.

If it's direct-drive, it's possible though unlikely the anode resistor overheated and it's resistance increased.

I have a few tubes that have poorly-lit cathodes; they were in a batch of used tubes of unknown origin and I suspect they are

at the end of their life. I can't rejuvenate them, either. I doubt your tubes are in this condition being only 3 months old.

[threeneurons]

Sounds like cathode poisoning.

This is a very important thing that everbody using nixies must know: Just as running a nixie tube with too much current, is bad. Running a nixie with too little current flowing thru it, is also a bad thing.

There may not be enough current flowing thru the tube, to allow the "ON" cathode, to shake off the crud that coated it, when another cathode was ON. Eventually, that crud keeps the really nasty coated sections, of that cathode, from glowing.

A few months of running at "UNDERcurrent" (too little current) will do what you're seeing. I'd just change out the anode resistors, with lower values. If its direct drive, measure the voltage drop, and calculate the current. Find a datasheet for that tube, and see what the minimum current is. Assume the voltage drop will be the same for the replacement resistor. Use Ohms Law, to calculate a resistance value that will meet that minimum current. Pick a real resistor value that's ~20% smaller, and use that for the new resistors.

You can measure the supply voltage too. Maybe it was too low from the start, and it would have delivered the correct current, had it been at the proper voltage. Absolute minimum supply voltage for direct drive nixies, is 170V. For multiplexed operation, you want a higher voltage. The higher the voltage, the faster, the tube turns ON. Typically, nixie tubes take between 15 to 50uS to start conducting, after voltage is applied. 

[Niek]

Remember also (from the earlier discussion) that the anode drivers are completely out of spec on this design (which may have caused the flickering). So, you can expect anything with a badly designed clock. I would just not bother with this clock anymore, as its design seems to have too many flaws. Perhaps you can rescue the nixies and put them in a better designed clock. Good luck!

[Dman777]

Ya, your correct. I should start over with a different kit for the INI-12 tubes. What are my options for kits out there? I like to have multi colored leds if possible and the kit needs to have a case. Also, I have a carton of 50 spare IN-12 tubes. 

Thanks,

-Darin

[Nicholas Stock]

Buy a Maestro from PV electronics (6xIN12) or a Lena from nixiekits.eu (4xIN12, 2xIN17). Sometimes in life you get what you pay for...I have both of these clocks and they're great, reliable and have been running for at least 1 year with no issues whatsoever.

Nick

Sent from my iPhone

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[Dman777]

The clock  I bought was a $150.00...on the same price tier as others in this category. It needs to be a 6 digit In-12 Clock. nixiekits does not have them and Maestro is sold out.

[Paul Parry]

Hi Darin,

Tell you what, I've been following your thread, and all the problems you've had.

Here's a deal for you to consider:

I'll let you have one of my Stainless Steel clocks, which inside has a PV electronics kit - well made and assembled. It will have also 6 X of the GN-4 tubes and a spare, not that you will need it. I will take your box of 50 IN-12's in part payment. I sell these clocks easily for £199.99 each - you can have one for £99 plus shipping.

I don't think there's many in this forum that will think that is a bad deal.

Best wishes,

Paul

[Dman777]

Hi Paul,

Thank you for the kind offer, but I rather hang on to my box of tubes. I will be getting the Maestro when it restocks. 

Thanks,

-Darin

[Paul Parry]

No worries Darin,

 

The Maestro is a fine clock, and well designed.

 

Cheers,

Paul