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 -- 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. To view this discussion on the web, visit https://groups.google.com/d/msg/neonixie-l/-/bdjhOqxMjRUJ. For more options, visit https://groups.google.com/groups/opt_out.
