That answers a few points. So overdriving tubes isnt necessarily a no no. I also didnt know poisoning occurs at too low a current, better put a minimum brightness limit on any new designs then. I have a dekatron circuit that uses 'pull mids', it works without them, I was wondering why they were there, I think your comments answer that question.
On 21 Sep, 10:24, fixitsan <chefin...@gmail.com> wrote: > On Friday, September 21, 2012 9:27:18 AM UTC+1, Jan Rychter wrote: > > > On 20 wrz 2012, at 19:50, Adam Jacobs <ad...@jacobs.us <javascript:>> > > wrote: > > > [about multiplexing] > > > > You forgot the other pro's: > > > > - reduced power consumption > > > - dramatically increased tube life at equal cathode current. > > > Ok, so has that actually been proven? I've seen opinions stating that tube > > life is dramatically increased and others saying that it is dramatically > > reduced. Some people say it has no influence at all. I'd really like to see > > a definitive (e.g. fact- or reasoning- based) statement on the matter. > > > Anyone? > > > --J. > > It is clear that the statement was correct, considering it quoted "at equal > cathode current" > > So take one nixe and turn it on , direct drive for 24 hours > Take another in a 1:4 mux which runs for 24 hours. in this muxed case each > tube is only on for 1/4 of the 24 hours. Therefore , where the cathode > current is the same in a muxed clock as for a direct drive clock, the tubes > in the muxed clock must experience lower utilisation levels, individually > speaking. > > Tube life is a function of cathode current (until the current is so low > that poisining could occur). That suggests something of a relationship > between lifetime and power dissipation. In many muxed designs the cathode > current is increased and therefore the nixie lifetime would be reduced if > the tube was always on. However, in a 1:6 mux although the tube is > dissipating more power due to the higher current, it is only active for > 1/6th of the time of an equivalent direct drive tube. > > I have seen several good statements made here, backed up with good theory, > which suggests that a doubling of cathode current in a 1:4 or 1:6 clock > doesn't affect tube lifetime when compared to a direct drive design using > lower current, which didn't appear to bring about any controversy. > > Personally, I've run a 1:6 mux with 2.2 times rated current and a 2:3 mux > with 1.6 times rated current, as well as a 1:2 mux (2 tube clock) with a > 1.4 current multiplier. All clocks were sufficiently bright for normal > viewing in a well lit room. Lifetime seems to not have been affected. There > were early scare stories about reduced lifetimes when datasheet lifetime > figures were considered sacred, but they all seem to have been false. > > The noise is often due to mechanical movement, I think it is caused by > electrostatic effects. I noticed in one clock which sufferedd badly that > when I changed the design so that instead of letting 'off' cathodes float > they were instead tied to a mid level voltage of about 90 Volts, via a > 'pull mid' resistor, that the noise was reduced. That might confirm that > floating cathodes adopt a high floating voltage which is quickly removed > when it is pulled to ground and that causes the electrostatic deflection. > By reducing the energy which needs to be discharged the movement, and > therefore the sound, is also reduced. > > Chris- Hide quoted text - > > - Show quoted 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 neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
