I'm finally posting this question, because I've been struggling with this problem for weeks, and even I'm quite familiar with "standard" electronic devices, I just can't work this very basic problem out I hope you can help me.
I retreived several Nixie tubes IN-14, and wanted to use them as a counter. I started with very basic installation on a bread board, and I wanted to control the display with a K155id-1 decoder. But my problem is : the tube seems to have an inverted polarity ! According to the data sheet, you normally connect 170V to pin 1 (anode), and ground to the pin corresponding to the selected digit. When I do it this way, the tube is light up completely, no figure on display, but when I invert the polarity, it works normally and I can get the right digits.
The problem is I cannot drive 170V throught a K155id-1... I'm certainly doing something wrong, but I really don't understand. All schematics I could find specify it should work with 170V on pin 1... my tube doesn't work like this.
I would really appreciate some help, I really don't see what I'm doing wrong.
The tube looks extremely bright with one digit lit (the 4). You must ensure that the current is limited to around 2.5mA with a series resistor in the anode circuit. Around 20k may suit and ensure that the voltage does not exceed 170v.
Hello there,
Thank you for your answer. As a matter of fact I did put a resistor (variable), around 40k Ohms in serial. You can see it (black round thing in the middle of the breadboard).
So I don't think it's cause of my problem...
Thanks and best regards,
Guy
Yes, I saw the variable resistor but could not of course see how it was set. The data for the tube is here including how to determine the common Anode and the cathodes for the digits/decimal points: IN-14 (Gazotron) Nixie Röhre - Nixie Tube . A manufacturing defect whereby the polarity of the device is somehow inverted would be extremely unlikely and more plausible would be a user error in interpreting the pinout (the illustration in the linked document is the view from the underside).
Hello,
Yes, I double-check the resistor is tuned to 40k Ohms.
I had the datasheet you mentioned in link, and I put the +170V wire to pin one ("Anode", shown by the arrow at the bottom), and the - wire to the dedicated pin ("Cathode 6"). Doing so, the grid is entirely illuminated, no digit displayed (see picture). When I swap the two wires, then I have a proper digit ("4") displayed.
I really don't understand what I'm doing wrong...
Thanks again for your help.
Guy
I thought about this also, but even if I can swap the wires, the problem is I cannot drive a +170 Volts through a K155ID1... +170V has to be fixed to the anode, and the ground pin is decoded by the K155ID1 chip. I really don't see how I can do it the other way round, with the ground fixed on the anode and the +170V decoded to the right pin !
Maybe I didn't make myself clear. I see a red and a black wire coming from what I assume is the power supply. What I meant was, how can you be sure that the red wire is in fact positive and the black wire negative ? Did you test this with a multimeter? A picture of the power supply also might help. Is it possible that the outputs are marked 0 and -170v.
Do you get the same effect when you attempt to light other digits on the tube or even with other tubes ?
Of course the polarity of the K155ID1 must be correct.
I tested the voltage from the power supply with a multimeter. There is a small screw on it for tuning the output voltage, and I set it on +170 Volts on the multimeter (red wire on red probe, and black wire on black probe).
I also tried with a second Nixie tube, same behaviour. The problem is certainly on my conception, but I just can't find where...
A K155ID-1 cannot work with 170V, can it ? I really don't understand, all schematics I found on Internet show the same set up.
The K155ID-1 must share a common ground between the Arduino and the 170v power supply and is connected to the cathodes of the IN-14 Nixie tube. It is not directly connected to the +170V power rail or Nixie anode. I don't see the common ground between the 170v power supply and the Arduino in your illustration. A missing common ground could certainly cause strange effects with a Nixie tube and cause multiple digits to be lit simultaneously as alternative ground paths are found.
Can you supply a link to the vendor page of that Nixie power supply if it is not similar to this one. High Voltage DC Step Up Converter Power Supply Module For Nixie Tube Board | eBay
Hello there,
Here is the power supply I'm using : 512V to 150220V Boost Converter Module MAX1771 Drive SZ31 QS301 Voltage | Fruugo UK
I chose that one because it takes 5V - 12V as input and I wanted to use an USB power supply in the final version.
But I will try the one you mentioned, I think you're right blaming the power supply...
Thanks for your help !
Guy
i use this one which i think is quite similar. And that has no problem.
I was following this thread and then looking for the schematic of my alarm clock, but i somehow couldn't find it.
I don't really want to take it apart to investigate, but what i do remember is that i use MPSA42 on every channel and i drive them through a simple bitshifter.
I never considered sinking that straight into a multiplexer though i know it can be done.
But anyway i am confident that the powersupply is not at fault here.
Hello,
Ok, I think I found the problem, big thank to all of you for your support !
It was so stupid... The power supply was effectively guilty, but it was simply the wires which were wrong : red was ground and black was +170V !!!
I checked again with the multimeter (I did it already, but I probably did it wrong or didn't notice the "-" sign on the multimeter !), and it's quite obvious...
So problem solved, sorry for bothering you with such a stupid problem, and thanks a lot for your support !
Best regards,
Guy
Usually I fix those by carefully releasing the pins and wire from the plastic connector housing and swapping them.
With pesky smaller versions that also have no well followed standard, I tie an overhand knot with both red and black wires, this is my reminder which might mean don't use, or use carefully, just something so I stop and think, like a string ties to my finger.
nb. Actually i bought 1 unit initially but it stopped working after about a year, probably because during construction i accidentally had the input polarity inverted briefly.
Hello,
Yes, for sure, I'll check properly next time. I'll go to bed cleverer than when I woke up this morning
Thank you very much for your help !
Best regards,
Guy
I hope you can help me.
It's now OK !