Polarity and current limiting resistor for INS-1 Nixie Lamps

[Paul S]

Hi! I've been using INS-1 nixie lamps for a while and they have always ended up flickering after a while. I think i might be doing a couple of things wrong. 

A) Polarity. They light up any which way you wire them. from the Datasheet (link) i can't definitively tell what is the anode and what is the cathode. I know the dot means something, but what it does I don't know. (Picture of INS-1)  I have tried wiring them either way and they still flicker... This is what I think it should be http://f.cl.ly/items/2u1p3x3V263X3e3M0s3o/Image%202012-09-29%20at%205.34.01%20PM.png, is this correct?

B) Current. I have a 170 VDC power supply with a 221k Ohm current limiting resistor. It has been been running at 0.55mA. 

I'm now trying a higher current limiting resistor that brings the current down to 0.45mA. Seems to be working, but I've had ones that worked before and then they start flickering. Thanks for any help!

[Michel]

Someone else might be able to confirm this but it looks to me like you
connected it up the correct way.

I just wonder one thing, if you see the light flickering as you say,
can you actually measure (with a scope) that the voltage across the
tube changes? If the voltage doesn't change, the tube is still doing
it's normal zener function.

Michel

On Sep 30, 8:20 am, Paul S <paul.c.sam...@gmail.com> wrote:
> Hi! I've been using INS-1 nixie lamps for a while and they have always
> ended up flickering after a while. I think i might be doing a couple of
> things wrong.
>
> A) Polarity. They light up any which way you wire them. from the Datasheet

> (link) <http://tubehobby.com/datasheets/ins1.pdf> i can't definitively tell

> what is the anode and what is the cathode. I know the dot means something,

> but what it does I don't know. (Picture of INS-1<http://f.cl.ly/items/2g0Z301L1c3f2y1R0n1e/Image%202012-09-29%20at%204...>)

> I have tried wiring them either way and they still flicker... This is what

> I think it should behttp://f.cl.ly/items/2u1p3x3V263X3e3M0s3o/Image%202012-09-29%20at%205...,

[pwalnuts]

I'm running the display under a PWM scheme for brightness. Right now even on full bright the duty cycle isn't 100%, more like 99%, so it's not flat. The voltage looks flat while it is on though.

[NoCampersFluffy]

Hello

I have the same issue occasionally with IN-3 neon bulbs.  Only some of the IN-3s flicker, the rest produce a constant glow.  The circuit I use is direct drive, no pwm and there is no variation in voltage.   I've played with both current and voltage but they still flicker after a few minutes, stop and flicker again.  They still work after a couple of years as part of logic circuits  so I think of the flickering now as a "feature".  My though was manufacturing variations are causing the effect.  Sorry no other insight for you.
Kind regards
Michael    

[Mike Mitchell]

There have been several topics in this group discussing the "wobble" problem with INS-1 neon lamps.

I've run into this problem myself using the INS-1 lamps as colon indicators for clocks.  One clock's colons are fine after six months, another has only one lamp working after 4 months.

Like you, I assumed that the dot/arrow indicate the cathode (negative) terminal.  Several other posts say that the dot/arrow indicate the anode (positive) terminal, like

https://groups.google.com/forum/?utm_source=digest&utm_medium=email/#!searchin/neonixie-l/INS-1/neonixie-l/KZccbl9bFIg/zffZFEdK1PQJ

or

https://groups.google.com/forum/?utm_source=digest&utm_medium=email/#!searchin/neonixie-l/INS-1/neonixie-l/awtYADE5WKo/b42oQ_JhfYIJ

I recently received a bag of 100 of the INS-1 lamps so I decided to experiment.  I rigged up a breadboard with a full-wave rectifier, 68uf of filtering and a bank of  220K current-limiting resistors. I connected the dot/arrow leg of the lamp to the negative supply, and the other leg through the current limiting resistor to the positive supply.  After several hours I would check for flickering/wobble.  If a lamp was flickering, I would reverse it's polarity so the dot/arrow leg was positive.  If the lamp still flicker after that I would remove it, move the lamps below it up one position on the bread board, and place a fresh lamp in the last position (dot/arrow to negative).

After performing this test I found twelve of the one hundred lamps did not flicker, and every one of them were connected with the dot/arrow to the positive supply.

On some of the flickering lamps I tried a 180k resistor instead of 220k, connecting positive to the dot/arrow.  The higher current through the lamp made no difference, the lamp still flickered.

   

[Tidak Ada]

You also can consider to use ac (directly from your hv-source)  for neon lights and triac optocouplers to drive them.

 

eric

---

From: neoni...@googlegroups.com [mailto:neoni...@googlegroups.com] On Behalf Of Mike Mitchell
Sent: zondag 14 december 2014 17:38
To: neoni...@googlegroups.com
Subject: [neonixie-l] Re: Polarity and current limiting resistor for INS-1 Nixie Lamps

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[Alejandro Logreira]

Hi all!

Regarding to this issue, i'd point out that, according to how Nixies work, the characteristic orange glow of nixies is produced very close to the cathode, and far from the anode. That's the same in the popular IN-12 and all others. http://www.explainthatstuff.com/how-nixie-tubes-work.html

By looking at the INS-1 glow, it seems to me that the orange  glow is produced very close to the cup-shaped electrode, that is, the one marked with a dot/arrow. So that one should be the cathode...

[threeneurons]

I'm of the opinion that the dot marks the anode, not the cathode, like this drawing which is alleged to be for the INS-1:

I'm not quite confident that it is, however. If you look at a regulator tube, such as an 0A3, you'll see that the largest surface makes up the cathode, and only a thin rod is used for the anode. The cathode after all, loses material during normal operation. If wire such that the cup, at the bottom is the anode, and the larger cylinder is the cathode, the sputtered material will come off the cathode and head towards the anode. This is away from the lens, so it should help keep it clear longer. Now this is all speculation. What would really be good, is if someone translated the known INS-1 datasheet:

[Dekatron42]

Using Abbyy Finereader and Google Translate it says:

----------

electrode output

1 - output of small cylinder : anode 

2 - output of large cylinder : cathode 

----------

to the right of the symbol.

/Martin

[RobG]

This translates to: indicator arrow is on the side of anode.