My $0.02 to add to Dennis' comments: My hearing is slightly diminished.. I've never heard any "singing" whatsoever from my 1x6 muxed clocks. My son has super-hearing, though (he can hear a CRT being turned on from across the house). I had him put his ear up to various 1x6 muxed clocks in the house (all IN-12, though) and he says he doesn't hear anything. I don't know if my results are atypical. Also, although I can see a faint flicker, if I look at the tubes with the corner of my eye, I can't see a flicker when I look at them dead on. I don't know if I have atypical vision.. I know I don't wear glasses. Your mileage may vary. ;) I would think a 2x3 mux would be just fine, provided you feed them with 180v or so. Don't try 170v with multiplexed nixies.
Yes, they do get dimmer when you multiplex them. You can drive them harder to make up for that if you want (with corresponding tube life reduction). Again, I think a 2x3 mux run at normal current (2.5ma in the case of IN-14) should be just fine as far as brightness and you'll get serious serious tube life. With that said, I have a direct drive clock that has run 24-7 for 8 years now. It just lost its first tube (an IN-14) about a month ago, I still haven't gotten around to replacing it. Interestingly, the IN-17's which have a shorter lifespan in their datasheet, are still glowing fine. I have been running these all at their rated current (2.5ma for the IN-14, 1.5ma for the IN-17). Never "underdrive" a nixie tube. It will fail fairly rapidly due to cathode poisoning. I've never tried the 555 or Max1771, I always use Mike's MC34063 mk1.5 circuit. I've found that it doesn't really care how I lay it out. I'm happy with it. It would definitely run a 2x3 mux. Mike could tell you if it will also push direct-drive for 6 tubes (15ma) I assume that it would, though. This brings me to another topic, though. a 2x3 (or 1x6) mux will use less electricity and require a smaller power supply (wall-wart). I like to buy 100ma 12v supplies for my 1x6 clocks. A smaller supply is cheaper and smaller. I've got a 6 tube (IN-8) direct-drive clock that requires 1a @ 9v... yuck. Oh, and multiplexing really is less wiring. for a 1x6 mux, you need a single 74141, which is run to all of the tubes in series. Then your little anode drivers (2 transistors, a handful of resistors) x 6, and that is about it. Only requires 10 I/O pins. Direct drive will need 24 pins and 6 74141's. (Oh, did I mention that the 74141 uses a ton of current?) -Adam On Wed, Aug 3, 2011 at 3:55 PM, Ryan McDonald <[email protected]>wrote: > Ok. I've decided that my 6-tube clock will either do a direct drive > using six 74141's and three shift/latch chips *OR* a 2x3 mux. I'm > kinda leaning towards the direct drive because it won't sing or > flicker. Questions: > > Will the 2x3 mux really be noticeably dimmer? I know folks say that a > 1x6 really sings. Can anyone comment on whether a 2x3 sings/flickers > and how noticeable it is? > > I'm concerned about tube life with direct drive since the duty cycle > is 3 times higher over a 2x3 mux. Can the tubes be dimmed by > increasing the anode resistor WITHOUT stressing the tubes (ie. is it > unhealthy to "underdrive" the tubes assuming you at least make the > strike voltage)? > > I know most folks here on the list prefer the max1771 based supply > over the common 555 based one due to efficiency. I have read though > that the 1771 ps is *very* finicky to things like board placement, > lead lengths, and component flavors. The 555 seems simpler and more > reliable at the expense of efficiency. Firstly is this true? And > secondly, would the usual 555-based design be adequate to drive six > IN-14's? > > -Ryan > > -- > 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. > > -- 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.
