IN-13 currents

[Joe Croft]

Hi Yall,

 I am playing with IN-13 nixie indicator tube. I am driving them with a similar circuit as I found here: http://forum.arduino.cc/index.php?topic=158113.0 Unfortunately, I have a few issues. First my tubes don't all light up unless I put 150V across them and it's much more reliable if I have 160V. second, the resister from the emitter to ground has to be 220 ohms instead of 620 ohms. This of course puts the current when fully lit at >13ma. The specs on the sheet say the absolute max is 4.5ma for a long and healthy life. 5.6ma is a short life :(

What am I doing wrong?

Thanks,

   Joe

[gregebert]

I've briefly experimented with IN-9's, and I found them to be erratic. Other people on this group have had better results, so I would conclude there was inconsistent quality when these were manufactured. You might get luckier with another batch from a different seller.

I,too, found that I needed a lot more current than the spec limit to get the tube more than 50% illuminated. Afterwards, I found that the tube would illuminate from the opposite end. Off to the junkbox....That was about 4 years ago, and they've been there ever since.

In the end, I used strings of NE-2 bulbs instead of the linear tubes for my project. They are plentiful, better quality, inexpensive, and much brighter than linear tubes. If that's an option for you, you may want to consider it.

[Jon]

I don't see a circuit in the link - it links on to a dead site. Can you post here? Some thoughts...

Are you sure you are using IN-13 not IN-9 ? 13mA to fully light the tube is around what might be expected for a slightly cathode poisoned IN-9. It's easy to check even if the tube markings have worn off: IN-13 has three terminals, IN-9 has two.

I would expect both tube types to require about 150V to strike reliably, and then the voltage across the tube will drop down to the maintenance or running voltage in the 95V - 105V range. Were you anticipating something different?

Jon

[Joe Croft]

Hi Jon,

I have embedded the picture below. It's a good guess if you post the circuit on a forum, you don't mind others re-posting it. I am definitely using in IN-13. 3 legs vs 2, it's hard to miss the 3rd leg ;).

Gregebert,

Sadly, for the 'art' of the clock, it has to be an IN-13 if for no other reason, to keep the size of the board in check, not to mention the drivers!

-joe

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[Jon Jackson]

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[Joe Croft]

Once more, but this time with feeling....


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[Jon]

OK, that's better. Your problem is the 4K7 base resistor I think - not needed for this configuration. Base current is limited by the emitter resistor (620R).

Jon. 

[gregebert]

What purpose does the 3rd connection of the IN-13 serve ? According to the schematic it should be sourcing around 100uA. There is no such terminal on the IN-9; I'm wondering if the 3rd terminal results in more-stable operation ??

[Joe Croft]

My guess is that it keeps a little pool of ionized gass at the bottom of the tube so the line will always start at the bottom. That's just my guess though.

-joe

On May 18, 2016 1:32 PM, "gregebert" <greg...@hotmail.com> wrote:

What purpose does the 3rd connection of the IN-13 serve ? According to the schematic it should be sourcing around 100uA. There is no such terminal on the IN-9; I'm wondering if the 3rd terminal results in more-stable operation ??

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[threeneurons]

Though, the 4K7 is not needed, it does no harm. Even if the xstr had the minimal hfe of 25, there would be less than a 1V drop across that resistor.

I have a IN-13 running right now, on my nixie thermometer. The drawing of the pinout, is correct, from the viewed side of the tube. The aux cathode, specifies cathode, so it should be wired as shown. 

[Joe Croft]

Hi threeneurons,

What current does your in-13 draw to get it to show fullscale?

-joe

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[threeneurons]

~4.5mA. Just as advertised.

Just a note. These tubes do fail, in weird ways, after many hours of use. They may still glow, but it shows up at odd spots. I've noticed in the last few years, a lot of used tubes coming from Eastern Europe, being advertised as NOS. Its easy to spot with nixies and dekatrons, but not visibly obvious with these bargraphs.

[Jon]

I'm wondering if there's something we're not seeing on the diagram which is responsible for the observations - either on it's own or in combination with the 4K7.

So, short out the 4K7 - does that materially alter what you see? Second, tell us more about how Vc is generated - is it a reasonably stiff source for the kinds of currents needed here? Are you sure the voltage applied to the base is actually the value you are expecting it to be?

I've played extensively with these tubes and also the IN-9, and my experience is the same as Mike's with respect to the current - I can't think of an example where I didn't get a full scale signal out of an IN-13 with 4.5mA to 5mA going through it. They get a bit non-linear right at the top end, but other than that work fine.

Jon.

[gregebert]

Best thing to do is gather data for several tubes, and plot it. Inconsistent data suggests problems with the tubes; maybe they are used, out-of-spec, reject, etc units.

I would use a voltmeter and measure the voltage at the following locations, while adjusting Vc to obtain

(a) First speckle of light on the tube, (b) 25%, (c) 50%, (d) 75%, (e) maximum, which might not be 100%.

Measure Vc, Voltage at emitter, voltage at collector, voltage at the AUX pin, AND the +120V supply (it may not be constant, due to loading). Obviously you would enter this data into a spreadsheet because there are calculations that need to be done (tube voltage and current), and it does a good job creating plots.

Once you have that info, we can figure out what's going on.

Is the transistor getting warm ? Depending upon the case style it may only be capable of 625mW. From the circuit, I can see scenarios where you could exceed this if you're running at 160V and above 13mA.

[Joe Croft]

I do seem to have a problem with my board. I have pulled one of the tubes and just tried it on a bread board and life is good. Though in the board, not so good. I will have to dig harder on the layout. Something is just not right.

-joe

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