Hi, OK thank you very much! With heat problems, I was just thinking of a transistor not being used as a switch but linearly. For example, with a 50V drop across the transistor for some milliseconds * maybe 7mA = 350mW. Well that is not too bad over just milliseconds anyway.
I'll just try PWM.. an MCU with a lot of GPIO outputs, and a big pile of NPN transistors. They'll look nice in TO-92's if installed carefully. No muxing or anything. Depending on firmware, it could be a clock or a general purpose display. Regards, Soren On Friday, January 20, 2017 at 10:11:16 PM UTC+1, gregebert wrote: > > I would not use an RC circuit; not only would it be expensive, it would > require a lot of trial-by-error experimenting and it likely would be > susceptible to tube-aging and inherent differences between tubes. Stick > with PWM. > > I know for a fact that tubes of the same type, and even with same/similar > date-code, have different I-V characteristics from data I've gathered on my > own tubes. > > Heat shouldn't be an issue for your drivers, unless you use a really high > supply voltage or you use multiple devices in a single package. It's easy > to calculate. For example, if you have a +200V supply, and the tube > requires 150V to illuminate at 5mA, your driver will dissipate 250mW > maximum. In reality, you will have anode and/or source/emitter resistors > that will dissipate some of the ~250mW, so the heat dissipated by the > driver will be even less. > > My first clock is an extreme example: +340V supply, 160V across the nixie, > leaving 180V across the 75K anode resistor. That equates to 400mW; I > played it safe and used 1W resistors instead of 1/2W devices. The driver, > however, had essentially zero power dissipation because it's either on or > off. > -- 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/36dbc683-9f6d-4c48-a784-92373874ec15%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
