# Nixies: stupid questions.

wyager: Are you using an anode resistor? That's crucial. It sounds to me like something's up with your driver IC. Can you post a schematic?

No, what size resistor?

My circuit is as described - no resistors or caps or anything. The nixie plugs into the IC and 180v+, the arduino plugs into the four IC logic pins and the IC is also linked to +5v and GND. All the grounds are linked.

OK, that's a problem, but I'm not sure it's causing your problem. What nixies are you using? Most people reccomend between 15 and 33k resistors, but it really depends. What you want to do is find a resistor (and you will have to experiment between those two values) where when you measure the voltage across the resistor and divide it by its resistance to find the current passing through it, and it should the recommended (you could go a little under and be fine) current for the nixie tube (small tubes tend to be around 1.5mA, medium tubes 2.5mA, and large tubes 4+mA. A model number would help). You have to experiment because of the variable nature of the nixie tubes, no one is exactly alike. So if you use a 15k resistor and find that the voltage dropped over it is 30V, you know that you are passing 2mA through your nixie tube which should be fine.

Also, what are you using as a power supply? If your 180v power supply does not have a built-in output filter cap, you will want to install one. 1µF @ 250v is probably enough to adequately filter the voltage.

Also, one possibility is that your tube has a severe internal short or something (but this is very unlikely). I recommend (after installing the resistor) individually testing each digit (without a decoder IC) to make sure the tube works well.

Good luck with your nixie project, as I think you know I am doing the same thing. ]:D

CowJam:

wyager: Are you using an anode resistor? That's crucial. It sounds to me like something's up with your driver IC. Can you post a schematic?

No, what size resistor?

My circuit is as described - no resistors or caps or anything. The nixie plugs into the IC and 180v+, the arduino plugs into the four IC logic pins and the IC is also linked to +5v and GND. All the grounds are linked.

For what I know this should work. I have a couple of nixies here and I am starting to work with nixies those days. I will give a try to this setup (that should work, in my opinion) F

CowJam:

wyager:
Are you using an anode resistor? That’s crucial. It sounds to me like something’s up with your driver IC. Can you post a schematic?

No, what size resistor?

My circuit is as described - no resistors or caps or anything. The nixie plugs into the IC and 180v+, the arduino plugs into the four IC logic pins and the IC is also linked to +5v and GND. All the grounds are linked.

The resistor depends on the specs of the Nixie in question. For instance I have some sub-miniature Russian IN-17 nixie clones that are speced for 170V and 47k series resistor. The sheet I have says they will work at lower voltages and upto 82k series resistor. The series resistor goes on the anode to avoid having resistors for every cathode (which can directly connect to the driver).

That said I haven’t tried interfacing these tubes yet, I’ve merely verified they light up.

Thanks. They're number 12s. I got a dozen of them, sockets and the ICs from Ukraine (gotta love ebay!) - they look Russian (cyrilic writing on them).

I'll have a play tonight and see what else I can break ;)

I've got them working, thank you everyone (especially wyager).

I slapped a 33k ohm resistor on the anode and it's working fine now using a fresh IC (I've permanently damaged the first one).

Excellent! It was probably just too much current that damaged the old IC.

Yeah. I'll get the hang of this electrickery stuff eventually!

Spoke too soon! http://arduino.cc/forum/index.php/topic,50274.msg358237.html

No! That's awful! =(

I am following your experiment and as soon as I finish my pov experiment I will apply them to nixies... Where did you find the datasheet for yours? I have just tried to light up my IN-14 from my DCDC power supply but I am quite sure that the others little blulbs that I have, IN-3 (just neon bulbs) can't work at 170v...

I googled for it. Not sure I had a datasheet for my actual nixies, but I got the datasheet for the chips (which came with the nixies) by googling, and this is it: http://cowjam.co.uk/arct/k155id1.pdf

I've got some IN-35s which are just neon bulbs and they run fine at 180v (or whatever my circuit is running at) and ran fine with or without a 33k ohm resistor. These ones: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=390206146006&ssPageName=STRK:MEWNX:IT#ht_864wt_905

We bought nixies from the same vendor
Mine are those
http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=400174245756&ssPageName=STRK:MEWNX:IT
I am going to try to drive them at 170v and see…
After reading about your experience I was thinking that multiplexing and optocouplers should be the safest way…

Yeah, optocouplers are the way to go!

If I figure out what happened I’ll report back on here.

BTW guys, small neon bulbs should have at least 100K resistors (some use 200K) at 170+V or else they could burn out themselves or your circuit. I am able to multiplex them at 170v with a 100K resistor. Remember that the gas inside them will change its resistance until the voltage across the lamp is the sustaining voltage. A 200K resistor (which is probably better for long life) makes them look a little sputtery.

My A1As regulate themselves at 60V, which means that 110V gets dropped over the anode resistor. 110V/100000?=1.1mA. Almost twice the recommended amount, but I figure since I'm multiplexing... Still probably not healthy.

wyager, thanks a lot for the advice. I am going to follow it!

Federico: wyager, thanks a lot for the advice. I am going to follow it!

This ^ !

No problem. Also, 666 posts cowjam. 8)

the number of the beast ]:D

By the way i see that you (wyager) use a lot of transistors for driving your project. Don't you have a 74141 off hand?

ps. the optocouples i need, TLP627, are damn expensive :fearful:

Federico: the number of the beast ]:D

By the way i see that you (wyager) use a lot of transistors for driving your project. Don't you have a 74141 off hand?

ps. the optocouples i need, TLP627, are damn expensive :fearful:

I was basing my project off parts I could get from digikey and I couldn't find any HV nixie drivers. The MPSA42s were only like 5 bucks for 25 IIRC, so I just went with those. I suppose after the shift registers and resistors and perfboard, the 74141s off ebay would have been cheaper, but it was a learning experience anyway. :P

BTW, are the optocouples to protect the rest of the circuit from high voltage?