George Herold wrote: -------------------->Some retard posted:> > > > >Why measure past the rated voltage? You are never going to operate there. > > >You simply risk damaging the capacitor for no good reason. > > > I just want to say, that when people tell me *not* to measure > parts above and beyond the specs.. The more I want too. :^) >** Test 'em to destruction I say ... Just kidding, but current limited breakdown testing is simply the only way to do find out the actual limit of many parts. Carried out sensibly, it does no damage. Anecdote: I once purchased a quantity of MJ15030/31s from a popular components retailer in Sydney. These are medium power TO220 pak devices rated at 160V for use as output drivers in power amplifiers. Nearly all of them were *dead short* as purchased !! I got a very grumpy reaction when I returned them and refused to take more from the same bin. WTF - Motorola do not supply dead BJTs. I smelt a rat, someone had been at them before me. Turned out a local amplifier maker ( Chris from PTM Electronics ) "borrowed" hundreds of them from the same store to put through his quality checking process then returned any he did not like. His "process" involved the use of an old HP Curve Tracer, which is well capable of destroying such devices and had done so to a great many. Wot an asshole. ..... Phil
Film capacitor as power-supply filter
Started by ●October 7, 2019
Reply by ●October 19, 20192019-10-19
Reply by ●October 19, 20192019-10-19
On Sunday, October 20, 2019 at 1:42:51 AM UTC+11, jla...@highlandsniptechnology.com wrote:> On Sat, 19 Oct 2019 03:37:00 -0700 (PDT), Phil Allison > <pallison49@gmail.com> wrote: > > >Steve Lunatic Wilson wrote: > > > >---------------------------- > >> > >> > >> Why measure past the rated voltage? You are never going to operate there. > >> You simply risk damaging the capacitor for no good reason. > >> > >> The curve shown in fig. 4 is a generic curve. The actual curves are > >> different for each capacitor, and depend on variables such as those > >> described above. So it is impossible to represent all capacitors at once. > >> > >> You need to also try measuring the capacitor voltage with a constant > >> current source. That could give valuable new information. > > > >** This fuckwit troll is a pernicious false arguer and incorrigible context shifter. > > > >He is delusional to the extent he literally believes his own bullshit. > > > >Prefect candidate for the "Church of Scientology" don't you think ? > > > > He argues out of emotion rather than reason. I have several anti-fans > here who are dying to show me wrong, and will commit any bogus mental > contortion in that cause.As if John Larkin doesn't.> This is amusing, because I'm really interested in how people reason > toward truth, and especially how they don't.But is unwilling to study his own behaviour in that context. Any train of thought that suggest that John Larkin is less than perfect gets ruthlessly repressed. -- Bill Sloman, Sydney
Reply by ●October 19, 20192019-10-19
On Sunday, October 20, 2019 at 10:20:34 AM UTC+11, jla...@highlandsniptechnology.com wrote:> On Sat, 19 Oct 2019 15:23:03 -0700 (PDT), Phil Allison > <pallison49@gmail.com> wrote: > > >jla...@highlandsniptechnology.com wrote:<snip>> >> This is amusing, because I'm really interested in how people reason > >> toward truth, and especially how they don't. > > > >** Same interest here - the sheer, bloody irrationality of most people is STAGGERING ! > > > >The fact was driven home to me forcefully soon as I began posting on usenet, about 20 years ago. People make up their minds about something in a flash, using great gobs of false logic plus "intuition" - then will not back down at any price. > > > >That so many seemingly bright people go right through college and university WITHOUT learning clear thinking or how to spot and avoid logical fallacies is a crime. > > > >I could go on and on ... > > Let's be careful here; we are in dire danger of agreeing on something.Sadly, the prize example around here got a university education - admittedly at Tulane - and posts denialist propaganda about anthropogenic global warming whenever he posts on the subject. This displays a massive failure in critical thinking. His vanity prevents him from recognising this, and commits him to total faith in every last silly idea that Anthony Watts puts on his web-site. https://www.sourcewatch.org/index.php?title=Anthony_Watts -- Bill Sloman, Sydney
Reply by ●October 19, 20192019-10-19
On Saturday, October 19, 2019 at 9:29:31 PM UTC-4, Phil Allison wrote:> George Herold wrote: > -------------------- > > > Some retard posted: > > > > > > >Why measure past the rated voltage? You are never going to operate there. > > > >You simply risk damaging the capacitor for no good reason. > > > > > > I just want to say, that when people tell me *not* to measure > > parts above and beyond the specs.. The more I want too. :^) > > > > ** Test 'em to destruction I say ... > > Just kidding, but current limited breakdown testing is simply the only way to do find out the actual limit of many parts. Carried out sensibly, it does no damage. > > Anecdote: > > I once purchased a quantity of MJ15030/31s from a popular components retailer in Sydney. These are medium power TO220 pak devices rated at 160V for use as output drivers in power amplifiers. > > Nearly all of them were *dead short* as purchased !! > > I got a very grumpy reaction when I returned them and refused to take more from the same bin. WTF - Motorola do not supply dead BJTs. > > I smelt a rat, someone had been at them before me. > > Turned out a local amplifier maker ( Chris from PTM Electronics ) "borrowed" hundreds of them from the same store to put through his quality checking process then returned any he did not like. > > His "process" involved the use of an old HP Curve Tracer, which is well capable of destroying such devices and had done so to a great many. > > Wot an asshole. > > > ..... PhilHuh, I mostly buy from digikey, (newark/mouser/..) I got some crap 79l12 (to-93 pack) voltage regs from jameco ~20 years ago, and never more. Good vendors and good customers, both should be cherished. George h.
Reply by ●October 19, 20192019-10-19
George Herold wrote: ---------------------> Anecdote: > > > > I once purchased a quantity of MJ15030/31s from a popular components retailer in Sydney. These are medium power TO220 pak devices rated at 160V for use as output drivers in power amplifiers. > > > > Nearly all of them were *dead short* as purchased !! > > > > I got a very grumpy reaction when I returned them and refused to take more from the same bin. WTF - Motorola do not supply dead BJTs. > > > > I smelt a rat, someone had been at them before me. > > > > Turned out a local amplifier maker ( Chris from PTM Electronics ) "borrowed" hundreds of them from the same store to put through his quality checking process then returned any he did not like. > > > > His "process" involved the use of an old HP Curve Tracer, which is well capable of destroying such devices and had done so to a great many. > > > > Wot an asshole. > > > > Huh, I mostly buy from digikey, (newark/mouser/..)** This was quite a while ago, about 1985. Companies like Farnell / Newark etc had not set up business in Australia then and getting trustworthy semis in small quantities was a regular hassle. Besides the damaged MJs, I got any number of Motorola fakes from well known outlets about that same time - mostly MJ15003/4 types from Dick Smith Electronics, remember the Aussie helicopter aviator ? I always got my money back and then did my level best to expose the scumbags who were still openly selling them. I received nasty lawyers letters and criminal threats for doing this on a local electronics forum. ..... Phil
Reply by ●October 20, 20192019-10-20
On Sat, 19 Oct 2019 18:29:26 -0700 (PDT), Phil Allison <pallison49@gmail.com> wrote:>George Herold wrote: >-------------------- >> >Some retard posted: >> > >> > >Why measure past the rated voltage? You are never going to operate there. >> > >You simply risk damaging the capacitor for no good reason. >> >> >> I just want to say, that when people tell me *not* to measure >> parts above and beyond the specs.. The more I want too. :^) >> > >** Test 'em to destruction I say ... > >Just kidding, but current limited breakdown testing is simply the only way to do find out the actual limit of many parts. Carried out sensibly, it does no damage. >Unless a part is very expensive, may as well test it to destruction. With some parts, the first indication of impending breakdown is failure. https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?dl=0 https://www.dropbox.com/s/gpc169hj1ilp6xa/photo01x_exploded_resistors.jpg?dl=0 -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●October 20, 20192019-10-20
jla...@highlandsniptechnology.com wrote: -----------------------------------------> > > > >** Test 'em to destruction I say ... > > > >Just kidding, but current limited breakdown testing is simply the only way to do find out the actual limit of many parts. Carried out sensibly, it does no damage. > > > > Unless a part is very expensive, may as well test it to destruction. > > With some parts, the first indication of impending breakdown is > failure. > > https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?dl=0 > > https://www.dropbox.com/s/gpc169hj1ilp6xa/photo01x_exploded_resistors.jpg?dl=0 > >** I have a TO3 lateral MOSFET with a neat, round hole in the top of the lid. Not the only example I have seen. Just below the hole is the top of the drain pin, somewhat burnt. ..... Phil
Reply by ●October 20, 20192019-10-20
mc@uga.edu wrote:> Is there any reason not to use a 20-uF 900-volt film capacitor as a power supply filter?Except for its price, no. I use 50uF/900V for the same purpose. But then it pays off to go to a much higher bus voltage with your PFC unit -- stored energy is roportional to V^2. The data sheet says that at 600 its useful life is expected to be 1e6 hours. Best regards, Piotr
Reply by ●October 20, 20192019-10-20
Piotr Wyderski wrote: -------------------> mc@uga.edu wrote: > > > Is there any reason not to use a 20-uF 900-volt film capacitor > > as a power supply filter? > > > Except for its price, no. >** Even that is NOT an issue. Compared to two, good quality, long life electros. https://au.mouser.com/ProductDetail/KEMET/C4AQCBW5200A3FJ?qs=sGAEpiMZZMv1cc3ydrPrF95ZAHiPXMKgQ3r3TgzZkS816veTKZI9aw%3D%3D https://www.partsconnexion.com/ATOM-76291.html ** $7 versus $36. .... Phil
Reply by ●October 20, 20192019-10-20
jlarkin@highlandsniptechnology.com wrote:> Unless a part is very expensive, may as well test it to destruction.Be careful doing that with electrolytics. The process of generating Al2O3 gives off hydrogen gas: 2Al + 3H2O --> Al2O3 + 3H2 (Gas) + 3e At high rates this can exceed the capacity of the capacitor to reabsorb and the hydrogen is released outside the capacitor. If the cap is in an enclosed space, a dangerous buildup of hydrogen gas can provide the basis for an explosion. A second problem is high current can cause heating which can boil the water in the electrolyte. The buildup of steam can rupture the case and result in an explosion. I had the unfortunate experience of an electrolytic explosion once. The cap was failing but I didn't know about it since the unit was in its case. When the cap blew, it left a dent in the 1/16 inch lid that clearly outlined the top of the capacitor. The inside of the unit was a mess of electrolyte and shredded aluminum foil. This was in the old days when the electrolyte was liquid and would slosh around when shaken. But don't underestimate the power of a steam explosion, and beware of caps that start to get hot.
