> One thing about Nixie tubes that you may not be aware of is that they need > some time to start firing, because the plasma is triggered by an external > source of energy such as a photon from the room lighting or a stray cosmic > ray. The less ambient light there is, the more time they need to start.
I was thinking about this and display efficiency. Obviously, efficiency would improve if anode resistors are dispensed with, but then it's left to the power supply to monitor and control current through a negative resistance. David's watch does this directly, by incorporating current feedback into the power supply. However, David's watch is direct drive. I was thinking about how to do this with a multiplexed watch. What I came up with is a little nuts, and probably would do horrible things to tube life, but I haven't tried it yet. I was thinking of using a circuit like the General Radio 1538 Strobotac, which has a cute way of building up charge for its flashtube by running a flyback type converter with a pulse train, charging up a storage capacitor incrementally until it has the desired amount of energy (they also claim nearly 100% efficiency, as their device can operate from batteries as well). This would be an interesting concept for a multiplexed nixie display: configure the cathode drivers, then dump a packet of charge into an anode capacitor. If the voltage is high enough, ionization should be gratifyingly fast. Since the capacitor is small, the total amount of energy would be limited. However, this would be running a nixie rather like a flashtube, with brief, high-current pulses. The duty cycle would be tiny, but the overload would be great. What this would do to tube lifetime, I don't know. It might be just fine, it might blast the cathode to pieces in hours. It would also be hard on the cathode drivers, but you can get SCRs in SOT-23 packages that can withstand 7A repetitive pulses (STM P0102BL, for example). - John -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
