A few might fail. If you were repairing TVs 20 years ago you only saw the one in a million that failed. I'd guess a dozen of these NTC Thermistors are in every house in the world and few people ever notice them.
OK, you like switches and timers. If a circuit breaker is popping then my guess is that you might be switching an inductive load. Where does the energy in the magnetic field (back EMF) go? Is it finding a path through the circuit breaker? I've never tripped a breaker with a switched circuit like that but I've have a problem with a switched inductive load tripping GFCI protected circuits (All outdoor and garage circuits are GFCI.) Look for common problems like your outlet is misfired and you are actually switching the neutral or if this is 220 that you are using a couple pole switch. On Thu, Feb 4, 2016 at 10:25 AM, Gene Heskett <ghesk...@wdtv.com> wrote: > > http://www.ametherm.com/inrush-current/inrush-current-faq.html > > It is an attractive idea, Chris, but from my experience in servicing tv's > etc with them included to serve as degauser drivers, the failure rate > has been noticeably often. They fail high R, get progressively hotter > as the R rises, and can affect the life of nearby parts from that heat, > or even cook the degausing circiutry, and thats a large enough item to > be considered a fire hazard. I have seen several that self destructed, > leaving just the wires sticking up out of the circuit board with little > balls of melted copper on the ends of the wires, or hanging on the > terminal strips prior to PCB's taking over from discreet circuitry. > > I thought of it, and the memory came back of all the failures in crt > based tv's and monitors, so it was discarded. I have enough fire hazards > on my premises as is. > > Thanks for the idea though as it gave me a reason to explain why I didn't > do that. Or, did I chase electrons for a living for too many years? > Over 65 now. :( > > > On Wed, Feb 3, 2016 at 11:46 PM, Gene Heskett <ghesk...@wdtv.com> > wrote: > > > On Wednesday 03 February 2016 21:38:27 Jon Elson wrote: > > > > On 02/03/2016 02:09 PM, Gene Heskett wrote: > > > > > Now I have spent 20 minutes doing a slow dance on those 2 > > > > > buttons, and haven't tripped the breaker yet, probably > > > > > more than 50 full cycles. > > > > > > > > Well, still don't exactly know why it wasn't working > > > > before. Did these charge pumps DIRECTLY drive the SSRs? I > > > > can easily see how marginal or decaying analog outputs from > > > > a charge pump could do unwanted things to an SSR, like make > > > > it conduct ONLY on one polarity for a couple cycles as the > > > > charge pump cap was draining. In fact, if you give typical > > > > SSRs marginal input voltages, I'll bet most of them will do > > > > this. > > > > > > > > Jon > > > > > > You could have hit it squarely there, Jon. Perhaps the > > > mosfet/hexfet output might have been replaced with a comparator with > > > a bit of a schmidt trigger hysteresis so that the output wasn't ever > > > in that grey area. I'd be a bit spooked about running it all on a > > > normal logic voltage supply though. I did note that I had quoted > > > the wrong voltage yesterday, coming out of the buck switcher, its > > > display says 25.6 volts, not 12. But since the original 4000 family > > > of cmos logic can and has survived on 28 volts on my watch with only > > > nominal heating while being switched at 1/4 microseconds speed, I'm > > > sure it could survive a nearly dc mode. RCA only rated it for 15 > > > volts in their propaganda. > > > > > > There is such a circuit I've seen someplace that used 1 gate of a > > > 4050 inverting buffer, with it driving the other 5 gates in the > > > package so the end result is non-inverting, and that can easily > > > supply 50 mills of output, and ack the SSR data we need 4 mills. > > > > > > One could adjust the trip point, since it would be at nominally 50% > > > of VCC, simply by adjusting the supply VCC, so if the bucker was > > > turned down to about 7.5 volts, the on/off response would > > > essentially duplicate the nominally 3.75 volts on point of the > > > hexfet. > > > > > > Hind sight, 20-05, I never thought of that when I laid it out in > > > pcb. :( Perhaps I should? That would make the board wider, or > > > longer, but its nominally .9 by 1.75" now. Where I have them > > > mounted, width could go up an inch w/o impinging on the rest of the > > > stuff in that box. > > > > > > With that amount of gain in the buffering, I doubt if any schmidt > > > triggering hysteresis would be needed to get a clean switch. About a > > > .05 u-f feedback capacitor from the output back to cF to speed it up > > > would be a great plenty I'd think. > > > > > > Food for thought and experimentaton when I am next bored. But its > > > working with the big current limiting resistor now, and its only > > > heating 2 or 3 degrees per on/off cycle to do it, so my natural > > > tendency toward lazyness and to not fix what isn't broken will > > > likely detour that effort. Sad, but as a former Bro-in-Law used to > > > say, its good enough for the girls I go with. :) > > > > > > But I'd like to get this furniture project done & delivered while I > > > take a grand tour to Nebraska & Kansas to deliver 3 of them to my > > > son's sometime this summer before I fall over. And get a couple > > > small 45 degree dovetail mills ordered so I can hack out a teeny QC > > > mount for this endoscope camera. Then I can do double sided PCB's > > > without all the foolishness changing the tool out for a sensing > > > contact to locate a hole in piece of brass tubing set into the > > > corner of the pallet & calculate all the offsets needed to do the > > > back side of a board. That got quite tedious on the toy mill too. > > > > > > Snooping around on fleabay last night I found this: > > > > > > < > > > http://www.ebay.com/itm/1-PC-3-8-X-45-DEGREE-PREMIUM-HSS-DOVETAIL-CU > > >TTER-MILLING-HIGH-SPEED-STEEL-/131511946248?hash=item1e9eb90c08:g:Jmc > > >AAOSwBahVVON- > > > > > > > > > Which looks like a decent price, but the pix doesn't match the > > > description, so which is correct? If its as small as it claims, it > > > would be ideal. I thought of hitting the buy it now for 4 of them > > > since they are HSS and would need to be drowning in cutting oil. > > > Should I? > > > > > > Cheers, Gene Heskett > > > -- > > > "There are four boxes to be used in defense of liberty: > > > soap, ballot, jury, and ammo. Please use in that order." > > > -Ed Howdershelt (Author) > > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > > > > -------------------------------------------------------------------- > > >---------- Site24x7 APM Insight: Get Deep Visibility into Application > > > Performance APM + Mobile APM + RUM: Monitor 3 App instances at just > > > $35/Month Monitor end-to-end web transactions and take corrective > > > actions now Troubleshoot faster and improve end-user experience. > > > Signup Now! > > > http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > ------------------------------------------------------------------------------ > Site24x7 APM Insight: Get Deep Visibility into Application Performance > APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month > Monitor end-to-end web transactions and take corrective actions now > Troubleshoot faster and improve end-user experience. Signup Now! > http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
