Hi everyone and thanks for letting me join the group! I am trying to build a multiplexed clock using IN-14 nixies, and have run into a problem.
In order to get acceptable brightness, in pulsed mode, the current has to be much higher to make up for the fact that it is only on for short pulses. >From the data sheet https://tubehobby.com/datasheets/in14.pdf : *For 'direct drive':* *Firing voltage (no more than) 170V * *Current for digits (no more than) 2.5mA * *Multiplex mode :* *Power supply voltage 190V * *Average current for digits 0.7 - 1.5mA * *Pulse current for digits 7 – 13mA * *Pulse width (no less than) 70µS * *Period 1 – 1.8 kHz * However, I cannot achieve those currents. When I tried calculating the anode resistor value I wanted, (using http://www.csgnetwork.com/anoderescalc.html) - using supply 170, sustain ~130V, current 13mA, it suggests an anode resistor of around 2.6K, but when trying this value, I found that the current that flowed was more like 6mA, and the voltage across the resistor was 10V, and 160V across the nixie. For further testing, I briefly tried WITHOUT *ANY* anode resistor. It was extremely bright, with an anode current of around 8mA - and not more! I checked the PSU voltage while doing this, and it was still at 170V, so the voltage wasn't sagging. Obviously this would kill the tube if left on for any length of time, but for testing purposes it illustrates my issue. I've tried briefly with a couple of IN14s and even an IN12, and the above is roughly consistent. So this leads me to a couple of questions: 1) Seeing as the data sheet seems to take care to specify a higher voltage for multiplex mode, am I to assume that for some weird reason, the nixies don't behave as I'd expect when you are trying to flow larger currents? ie they don't actually try to pull the supply voltage down all the way to Vsustain? Do I need to increase Vsupply to 190V to achieve higher currents e.g 13mA? 2) If I am happy with the current of 8-9mA at 170V without an anode resistor while multiplexing, does it mean that I can (in this specific application) get away without an anode resistor then? Suggestions welcome! Thanks David -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/7f8e1fd5-d144-452b-8805-35847d8204f4%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
