[neonixie-l] Re: How often does a 74141 go bad, or arrive dead?
But the powersupply, which is the simplest part of Mike's circuit, would need a complete overhaul. TTL parts need a solid +5vdc and won't work with Mike's unisolated zener shunt logic supply. Also, as you say, the 74142 won't work at the 250vdc provided by the unisolated DC doubler circuit. Probably I'd do the AC wall-wart, 7805 (or bucking switcher) boost switching supply... That right there takes away a lot of the simplicity that the 74142's add to the circuit.. One can always use the back-to-back transformer trick. 220V:6V - 9V:220V will give about 180VAC 220V:6V - 12V:220V will give about 110 VAC Simplicity itself, and if one adds a nice tube shunt regulator, 2x0B2 in series, it has a +10 in coolness :) Gastón -- 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 this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: How often does a 74141 go bad, or arrive dead?
I might just have to add some 0B2's to a nixie clock just for the coolness factor now. :) Antique Electronics Supply has them for $6 each. :) -Adam On 7/27/2011 5:44 AM, GastonP wrote: Simplicity itself, and if one adds a nice tube shunt regulator, 2x0B2 in series, it has a +10 in coolness :) -- 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 this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
[neonixie-l] Re: How often does a 74141 go bad, or arrive dead?
| 250vdc supply on his board would be too hot for a 74141 so probably | too hot for a 74142.. Maybe a transformer supply.. | | -Adam W7ATJ 250V is a tad too hot for a 74141. Western 74141s had zener clamps at ~60V, an from experience the Russian parts started to breakdown ~100V. So if a nixie turns OFF ~130V, then the max supply is either 190V (130V +60V), maybe 230V (130V+100V) for a Russian part. If you use a MPSA42, which is good to 300V, then the supply can go upto 430V (assuming 130V minimum sustain. 130V is only a ballpark number). Your anode resistors might get a tad hot, if use that extreme of a voltage. In practice, nixie supplies should be in the 180V to 200V range. 170V is the absolute low end (direct drive only, too low for MUX'd circuits). 220V probably the high end limit, if you use the 74141. -- 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 this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: How often does a 74141 go bad, or arrive dead?
I'm just wondering how practical it would be to reproduce mike Harrison's circuit with 74142's. His primary design consideration was only modern parts, simplicity cheap component costs... While his design is logically simple, it's not simple to build.. He has 28 MPSA42 drivers. 1 of which is to drive the 10 hours (1) cathode, another is used to drive the blinking neon(s). That leaves 26 MPSA42 drivers that could be replaced with three 74142's used in place of their CMOS decade counters. That's $21 to replace maybe $5 worth of parts.. so we're +$15 at that point. But the powersupply, which is the simplest part of Mike's circuit, would need a complete overhaul. TTL parts need a solid +5vdc and won't work with Mike's unisolated zener shunt logic supply. Also, as you say, the 74142 won't work at the 250vdc provided by the unisolated DC doubler circuit. Probably I'd do the AC wall-wart, 7805 (or bucking switcher) boost switching supply... That right there takes away a lot of the simplicity that the 74142's add to the circuit.. Probably explains why I haven't ever seen anybody do it. :) Still, an interesting thought experiment. -Adam On 7/26/2011 12:13 PM, threeneurons wrote: | 250vdc supply on his board would be too hot for a 74141 so probably | too hot for a 74142.. Maybe a transformer supply.. | | -Adam W7ATJ 250V is a tad too hot for a 74141. Western 74141s had zener clamps at ~60V, an from experience the Russian parts started to breakdown ~100V. So if a nixie turns OFF ~130V, then the max supply is either 190V (130V +60V), maybe 230V (130V+100V) for a Russian part. If you use a MPSA42, which is good to 300V, then the supply can go upto 430V (assuming 130V minimum sustain. 130V is only a ballpark number). Your anode resistors might get a tad hot, if use that extreme of a voltage. In practice, nixie supplies should be in the 180V to 200V range. 170V is the absolute low end (direct drive only, too low for MUX'd circuits). 220V probably the high end limit, if you use the 74141. -- 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 this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: How often does a 74141 go bad, or arrive dead?
I never really thought of these older ICs having seals, but it makes sense, in the sandwich sense. I looked at one of the Fairchild 74141s, and where the epoxy is sandwiched between the ceramic, sure enough, there's a hole in there. I thought it was a bubble, but using a high tech tool called a needle I poked the bad chip, and it goes a ways in. Shame. I have two other Fairchild chips to use (test first), and then I have about twenty Russian K1551D1 in stock. Fingers crossed Shane On Fri, Jul 22, 2011 at 10:08 PM, Terry S tschw10...@aol.com wrote: I'm starting to see a dramatic increase in the rate of failure on old chips like that, both at home and in my lab at work where I have drawers full of old TTL and CMOS -- in anti static packaging. I think that the hermetic seal of the IC packages are breaking down over the decades. Typically the legs show high rates of tarnish on the failure prone chips, but I see that on good chips as well. I suspect the failure rate will go up. It doesn't bode well for a lot of old equipment and computers that employ these parts. Terry On Jul 22, 8:08 pm, Mimewar mime...@gmail.com wrote: I'm up to three tubes, (coding takes longer than wiring) funny thing is, the first 74141 (Fairchild I assume by the capitol F) wouldn't display 5 or 6, so I swapped it for another, this time the 4 stays on all the time. I tried a third, and that one works. I have caps added across all ICs, and the third try worked. Is this common? Are the Russian 74141s better than the US? Thanks Shane -- 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 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 neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
Re: [neonixie-l] Re: How often does a 74141 go bad, or arrive dead?
On 11-07-23 10:53 AM, Shane Ellis wrote: I never really thought of these older ICs having seals, but it makes sense, in the sandwich sense. I looked at one of the Fairchild 74141s, and where the epoxy is sandwiched between the ceramic, sure enough, there's a hole in there. (Oh no, another back in the day story) When I was in High School, the eelctronics teacher Pulled in a few favours and got the class a tour at what was then Microsystems International Limited ASA Corkstown Labs, AKA Northern Electric Semiconductor. At the time they were doing stuff like making 747 Op amps and the diodes for the receiver of Northern electric telephones. (the one that cuts the dial click) They explained taht they tested the seal on the diodes by by putting a batch in a chamber with radioactive gas. after a while they puped the gas away, and any diode that was radioactive was assumed to be leaky and junked. The lab later became part of BNR, then Nortel Networks. Last I heard SGS has some space there as well as Abbot Point of care, to make Istat medical tests which also require a clean room. -- Charles MacDonald Stittsville Ontario cm...@zeusprune.ca Just Beyond the Fringe http://www.TelecomOttawa.net/~cmacd/ No Microsoft Products were used in sending this e-mail. -- 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 this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
