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IN9 Nixie Tube - Getting a Full Scale

Discussion in 'General Electronics Chat' started by micr0man, Sep 15, 2014.

  1. micr0man

    micr0man Member

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    Hi,

    I do not use this forum very often, and mostly just hide in the chat, but I have come across a problem which I can't figure out what the problem is, so I'm hoping maybe somebody could give me a bit of help. I have a few IN9 bar-graph nixie tubes sitting on my desk which I decided to attempt to interface. I created a HV supply, from stepping down the 230v mains to 50v, rectified to ~71V and then doubled using a voltage doubler to 141V. The datasheet says that the max firing voltage is 140V, but due to the low current I am getting more like 160V on the transformer output which is good.

    I am controlling the current with a transistor giving me a variable current of around 0-20mA, but here is where my problem lies. For some reason, I am not getting a full bottom to top scale on the tube, even when the multimeter is saying up to about 19mA. At about 12mA, the tube is just getting brighter as is expected to do when at the top of the scale. I have tried multiple tubes with the same outcome, so I was wondering if I am doing anything majorly wrong.

    I know quite a few of you dislike the java circuit simulator, but I have here a basic simulation of the circuit and it seems to work well enough: Falstad Circuit Simulator - Nixie Control

    This is the schematic:
    [​IMG]

    It could be the worst video you've ever seen, without any explanation but you can quickly see what is happening in this video:



    Thanks again for the help anybody can give,

    Dave
     
  2. killivolt

    killivolt Well-Known Member

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    You might not be sinking enough current. Here is a schematic of a IN-13 nixie the IN-9 is more difficult than the 13. Interesting project looks fun:)
     

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    Last edited: Sep 15, 2014
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  3. dr pepper

    dr pepper Well-Known Member Most Helpful Member

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    I had the same problem with an iv13 tube, the 2 wire one, not enough current can cause it but if its new then it might not be burned in, there are different ideas on this but i left mine for an hour on full scale, been ok since.
     
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  4. dave

    Dave New Member

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  5. micr0man

    micr0man Member

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    Hi, Thanks for the reply KV,

    Thanks for the reply, from what I can tell he seems to be doing almost the same thing as I, just a slightly different value resistor accounting for the in-13's wanting a little less current and only having 5v on the transistor base.

    However dr pepper you seem to have hit the nail on the head. I've been giving it a steady 11.77mA for the last 10 minutes and I'm watching it slowly creep up the tube. I'm presuming this will stick and will not creep in the future?

    Thanks again for both of your suggestions. Looks like I'll just have to break them all in
     
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  6. dr pepper

    dr pepper Well-Known Member Most Helpful Member

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    Burn it in then see how it goes, with a bit of luck it'll be fine.
     
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  7. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    Line 4 is the ionizing voltage. 140V ( THIS IS THE TRIGGER VOLTAGE)
    Line 5 is the maintenance voltage. 70V ( THis IS THE FOLDBACK VOLTAGE DROP VALUE USED TO CALCULATE CURRENT)
    Line 6 is the maximum milliamps at which the bar is fully lit. 12mA (!!@ mA WITH ADEQUATE VENTILATION GIVES 2000 hr LIFE, 10mA is longer, stacked hot tubes is shorter life.)

    To minimize power waste across the current limiting resistor, it is important to be more efficient with 100 tubes.
    A more efficient design would require a 140~200V trigger pulse and high current 100Vdc regulated to give 10mA for operation and maybe 150V for burnin. Power resistors with 10mA and 30V drop from 100V are 300mW but with 80V drop @12mA is 1Watt wasted * 100 tube resistors. More complex but more efficient.
     

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