Nixies: stupid questions.

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. ]:smiley: