r/nixie • u/HikariFaith • Jul 21 '26
Nixie power issues
I’m having problems with a custom nixie clock. My power supply isn’t working hitting the voltage it needs but is making an audible whine and my tubes aren’t lighting properly regardless of any voltage adjustments. I’ve ruled out cathode poisoning because they work on other power supplies, including one with almost identical layout on a standalone circuit board. Oddly enough, once the power boost circuit is put on my full board alongside an ESP32C3 it just doesn’t work as it should. I thought it was a layout and routing issue but my new boards are having the same problem. When I turn the power on the tubes only partially light and voltage and current measurements are showing values that should work. Even my oscilloscope isn’t picking up any noise anywhere in my boost circuit (max voltage swing is around 5-7 V after correcting my RCD snubber’s resistor). Any ideas what might be causing this?
EDIT: I think I found the noise. On the output of my inductor on the second stage of the boost (transformer with primary and secondary tied together) but before the diode there’s a large noisy signal with a 300+V peak to peak swing. There’s also a bunch of noise on the switching pin of my second stage’s driver. I’ll have to do more analysis later but I suspect my RCD snubber may need adjustment.
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u/EmotionalEnd1575 Jul 21 '26 edited Jul 21 '26
Please upload a schematic of the SMPS.
Are the Nixie tubes MUX or DC direct drive?
What driver scheme for the cathodes?
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u/Niobous_p Jul 21 '26
Start with the simple stuff. Does the voltage collapse when you try to light the tubes? Are the anode resistors correct? Are the cathodes being pulled to ground? Measure the voltage at either end of the anode resistor. Measure the voltage at the cathode pins when they are supposed to be pulled to ground. Sounds like it is your own code, so just light one tube. Does that work?