I have problem with my nixie clock. There are ghosts when changing numbers on the lamps.
I'm using multiplexing with TLP627 opto-coupler to control anodes and NPN MMBTA42 bipolar transistors to control cathodes. Transistors switch at 0.283 ms, TLP627 at approximate time. Extending the switching time did not help. I tried to solve the problem by extending the switching time of the lamps, but it had to be really long was almost 0.2 seconds, but was still ghosting. IN-14 lamp is powered by 180V, the current does not exceed 0.9mA on it. I'm running out of ideas ;(
Best Answer
I had a very same issue in my design of Nixie clocks. Changing switching time will not help. Try to connect all cathodes to pre-bias voltage of 100V via e.g. 220K rezistors. To get 100V, design a simple voltage divider from driving 180V.
To get more familiar with the issue, please refer to Section "OFF CATHODE CHARACTERISTICS" at http://www.zapro.dk/public/PDF/nixie/N101.pdf which discusses the magic behind.