No, the filaments are tungsten and tungsten has a huge positive temperature coefficient. The ideal drive would be a constant current, voltage capped source. A resistor approximates that quite well.
I would not connect them in series for the same reason it's a bad idea to connect vacuum tube filaments in series. I have an art deco tube radio that still works that has the tubes in series. Upon turn-on, one filament goes incandescent and then dims down to normal as the other tubes warm up. Needless to say, that tube doesn't last very long. John On 03/04/2017 03:34 AM, ten kowal wrote: > Do I understand correctly, that they work just like a resistor? > My plan is to drive IV-6 filament by directly PWMing it from 5V or 3,3V. It > normally requires 50mA@1V, so if the filament works just like a resistor, > can I PWM it with low duty cycle (4% on 5V and 9,2% on 3,3V)? Of course PWM > frequency will be something above 25kHz to avoid any noise. Will the wire > burn from short current spikes? > I don't like the idea of adding a dropper resistor. on 5V I will be losing > 4x the power needed to warm the cathodes! > Another idea is to connect 4 tubes in series. Of course it will make a > voltage gradient across tubes, but I plan to drive anodes at 50+V, so maybe > it won't be visible - does anybody have any experience with driving > filaments like that? > A step-down converter sounds good, but I will be very space limited in this > project. > -- John DeArmond Tellico Plains, Occupied TN http://www.tnduction.com <-- THE source for induction heaters http://www.neon-john.com <-- email from here http://www.johndearmond.com <-- Best damned Blog on the net PGP key: wwwkeys.pgp.net: BCB68D77 -- 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/d492bf1a-b1a6-e6cc-867f-cdb686033cb3%40neon-john.com. For more options, visit https://groups.google.com/d/optout.
