Michel, have you read the books: Cold Cathode Discharge Tubes by Acton & Swift Cold Cathode Tube Circuit Design by D M Neale Glimmröhren und Kaltkatoden-Relaisröhren by Otto Paul Herrnkind Glowlamp Manual by General Electric Kaltkatodenrelaisröhren Dekadenzählröhren by DR Roland Hübner Kaltkatodenröhren by Greiff Electronic Counting Circuits Techniques & Devices by MULLARD Ziffernanziegeröhren by VALVO
There is a lot about what happens inside a cold cathode tube in those books with explanations about charge, deionization and stuff - way above my head but it gave me a good ground to stand on when trying to understand more about what happens inside these tubes, and it was enough for me to understand it at a basic level. There are of course many more books that describe these phenomena, but those are the ones that I have borrowed from libraries and looked into. /Martin On 18 Feb, 11:56, Cobra007 <[email protected]> wrote: > I think you're right and that would explain why I can't really measure > the capacitive component. You're talking about negative resistance, I > had not looked at it that way but it sounds very reasonable, the > voltage over the tube will decay while the resistance increases so > that would indeed be negative. > > I do indeed use a pulse with series resistor, I let the voltage drop > from say 150V down to say 100V to turn the tube off. Normally, with a > capacitive load, the tube's cathode would then immediately drop to > -50V. This doesn't happen, it doesn't even go below 0V most likely > because the negative resistance wins over the capacitive properties. > > I think the inductive component is very small. At some frequency it > should resonate I would assume but I can't see that in my step > response so the inductance must be very very small. > > Michel > > On Feb 18, 1:51 am, John Rehwinkel <[email protected]> wrote: > > > > > > How does a nixie behave in the first few hundred micro seconds after > > > switching off. Is it resistive, capacitive or inductive? I would > > > assume it to be capacitive but that is not exactly what I measure. > > > That's a really good question, and I'll admit I haven't attempted to > > measure it. So, in the grand tradition, I'll take a guess at it. Said > > guess is that the plasma stays ionized for a bit before the atoms settle > > back down to ground state, so it would have the electrical properties of an > > ionized plasma, which would be: negative resistance. This would decay to > > capacitance as the gas became nonconductive. there's of course inductance > > from the leads, and the capacitance and inductance are distributed > > (especially in larger nixies), making a sort of sloppy transmission line > > with varying characteristics. Now I want to see if various nixies have > > resonant frequencies, and what I'd get back if I hooked a TDR to a really > > big one. > > > > It > > > seems more resistive, so I am wondering if this is normal or am I > > > doing something wrong? > > > I'm curious as to how you're measuring this in the first place. Are you > > using pulses with a trailing voltage and a series resistance, or what? > > > - John- Dölj citerad text - > > - Visa citerad text - -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
