Re: gEDA-user: electrolytic capacitors
On Monday 29 December 2008, Bill Gatliff wrote: >KURT PETERS wrote: >>Just curious, I wonder what's inside the blue one? >> >>:-) > >Turtles. All the way down. :) > ROTFLMAO! > >b.g. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) A banker is a fellow who lends you his umbrella when the sun is shining and wants it back the minute it begins to rain. -- Mark Twain ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
And then Little Cap A Took the hat off HIS head. "It is good I have some one To help ME," he said. "This is Little Cap B. And I keep him about, And when I need help Then I let him come out." >Just curious, I wonder what's inside the blue one? >:-) >Kurt > >> >> -- >> >> Message: 2 >> Date: Sat, 27 Dec 2008 11:53:44 -0500 >> From: Dave McGuire >> Subject: Re: gEDA-user: electrolytic capacitors >> To: gEDA user mailing list >> Message-ID: <0a94b1de-507f-4af9-9dd0-2886a8cd3...@neurotica.com> >> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed >> >> On Dec 27, 2008, at 5:40 AM, Robas, Teodor wrote: >> > Do not count on this kind of capacitors: >> > >> > http://deep-blue.ro/tmp/chinese%20capacitor.jpg >> > >> > :)) >> >> Oh. My. God. *shudder* >> >> That does it...I'm now going to stick EVERY ELECTROLYTIC CAPACITOR >> I BUY on a bridge before I use it. >> >> -Dave >> >> -- >> Dave McGuire >> Port Charlotte, FL ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
KURT PETERS wrote: >Just curious, I wonder what's inside the blue one? >:-) Turtles. All the way down. :) b.g. -- Bill Gatliff b...@billgatliff.com ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
Just curious, I wonder what's inside the blue one? :-) Kurt > > -- > > Message: 2 > Date: Sat, 27 Dec 2008 11:53:44 -0500 > From: Dave McGuire > Subject: Re: gEDA-user: electrolytic capacitors > To: gEDA user mailing list > Message-ID: <0a94b1de-507f-4af9-9dd0-2886a8cd3...@neurotica.com> > Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed > > On Dec 27, 2008, at 5:40 AM, Robas, Teodor wrote: > > Do not count on this kind of capacitors: > > > > http://deep-blue.ro/tmp/chinese%20capacitor.jpg > > > > :)) > > Oh. My. God. *shudder* > > That does it...I'm now going to stick EVERY ELECTROLYTIC CAPACITOR > I BUY on a bridge before I use it. > > -Dave > > -- > Dave McGuire > Port Charlotte, FL ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
>> Someone wrote: >> >> [Electrolytics] can explode pretty violently, so >> let me tell you a story. [...785V on a 450v >> cap...serious dent in plaster...] > Robas, Teodor wrote: > > > The resulting flame was always entertaining ! > Sometimes the ASIC wanted to take all the punch > and dig a hole the size of a finger in a 4 layer > PCB. The capacitor, only 220uF/50V, survived. I will second the "silicon and epoxy makes a more impressive explosion than electro/tants" theory The one I remember is a TO-220 fet. I was at a place that made and fixed power inverters ranging from 12VDC-240VAC units for running a TV up to 110VDC-415VAC as UPS units for small hospitals. Behind the shed where the units where tested and fixed was a bank of lead acid cells. These cells were the normal 2V very many hundred amp hour cells used in solar RAPS. The battery that was made from them had multiple taps on it 12v 24v 48v 110v obviously for testing different voltage inverters. One day the guy was testing a 12V unit that used 50N05 fets. No prizes for guessing which tap he mistakenly used instead of the 12V one. Anyways - there was 110V across the FETs that are rated to half that. The big lead acid batteries that could make fencing wire do a good impression of a light bulb. The test did not last long. Two legs of the TO-220 package stayed in the PCB. Most of the epoxy gone. The metal tab of the TO-220 embedded 10mm into a besser brick (breeze block) wall 1/2 a meter behind the unit. I was five meters away and had ringing ears. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
Dylan Smith wrote: On Sun, 28 Dec 2008, der Mouse wrote: [Electrolytics] can explode pretty violently, so let me tell you a story. [...785V on a 450V cap...serious dent in plaster...] My exploding cap story is not quite so impressive, but I know I certainly found it convincing. Neither is mine. When learning about switch mode (boost) supplies, Yep, boost circuits can also do a lot o damage. At the company I worked one of the managers had the 'brilliant' idea to make a software regulated boost supply. I can not blame him, they made a plus of 30 cents per board. The circuit was rising voltage from 12V to 37V for an ASIC wireless transmission chip. The ASIC chip was conected on SPI to a big Motorola controller. The controller gave the control signal for boost controller on a software regulated PWM output. The problem was that that the ASIC draw a few Amps when transmitting and almost nothing when off. Now guess what happen when the software was too busy to take care of keeping the ASIC transmitting ? The ASIC would stop. The voltage to power the ASIC (rated 42V) grew up to ~80V. That voltage killed the ASIC and came back on the SPI lines to the controller. The resulting flame was always entertaining ! Sometimes the ASIC wanted to take all the punch and dig a hole the size of a finger in a 4 layer PCB. The capacitor, only 220uF/50V, survived. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Sun, 28 Dec 2008, der Mouse wrote: > > [Electrolytics] can explode pretty violently, so let me tell you a > > story. [...785V on a 450V cap...serious dent in plaster...] > > My exploding cap story is not quite so impressive, but I know I > certainly found it convincing. Neither is mine. When learning about switch mode (boost) supplies, I got it wrong, and my circuit made near 1000 volts instead of 200. (The MOSFET only had a Vds of 500 volts, too, but I must have had a good one). Since I had my multimeter hooked up and it immediately went off scale high on the 1000 volt DC setting, I quickly yanked the supply. The capacitor didn't actually explode, but it certainly smelled bad and was bulging quite a bit. IIRC, it was rated 450V. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Sunday 28 December 2008, der Mouse wrote: >> [Electrolytics] can explode pretty violently, so let me tell you a >> story. [...785V on a 450V cap...serious dent in plaster...] > >My exploding cap story is not quite so impressive, but I know I >certainly found it convincing. I put together a circuit - can't even >remember what it was, now - on one of those solderless breadboards. >Turned it on and it seemed to be working, but then I heard this hissing >noise. I was just starting to try to locate it when the cap let go. >Fortunately it was a small one (perhaps half a millicoulomb rating); >all it did was make a bang and a small cloud, which settled in moments >to cover everything within about a 6" radius with a thin film of >something oily-feeling. Ethylene Glycol, very very pure antifreeze. >On reflection, I realized I'd been running it >at something like twice its rated voltage. That will generally do it every time. :) >Ever since I've been substantially more careful to think about voltage >ratings when selecting electrolytics. > >/~\ The ASCIIMouse >\ / Ribbon Campaign > X Against HTML mo...@rodents-montreal.org >/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B > > >___ >geda-user mailing list >geda-user@moria.seul.org >http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The cart has no place where a fifth wheel could be used. -- Herbert von Fritzlar ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
> [Electrolytics] can explode pretty violently, so let me tell you a > story. [...785V on a 450V cap...serious dent in plaster...] My exploding cap story is not quite so impressive, but I know I certainly found it convincing. I put together a circuit - can't even remember what it was, now - on one of those solderless breadboards. Turned it on and it seemed to be working, but then I heard this hissing noise. I was just starting to try to locate it when the cap let go. Fortunately it was a small one (perhaps half a millicoulomb rating); all it did was make a bang and a small cloud, which settled in moments to cover everything within about a 6" radius with a thin film of something oily-feeling. On reflection, I realized I'd been running it at something like twice its rated voltage. Ever since I've been substantially more careful to think about voltage ratings when selecting electrolytics. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Saturday 27 December 2008, Dan McMahill wrote: >Gene Heskett wrote: >> They can explode pretty violently, so let me tell you a story. Back in >> the mid-60's I came across a tube type, mobile cb radio that had to be one >> of the few attempts to build one for a 6 volt vehicle system, and predated >> the old Johnson whiteface by probably 10 years. My pickup at the time, a >> 52 ford, had long since been converted to 12 volts, and I was in the >> radio, on the kitchen table, moving wires to convert it to 12 volts. I >> missed one without realizing it, and had it running on a 12 volt supply >> for test. It worked really really well, talking to the neighbors on a >> piece of wire laying on the floor for an antenna. But after about 15 >> minutes the main filter capacitor let go, and the top of the can put a >> quarter sized print in the plastered ceiling that was about 1/4" deep. >> I'm glad I wasn't in front of it at the > >too funny. My exploding cap story is also related to automotive >electronics. The explosion happened at 2 AM when I was in high school. > Mom and Dad were not too thrilled about it if I recall correctly. > >Makes a lasting impression though doesn't it? > Yup, one I sure won't forget this side of the rapture. It left my ears ringing slightly, but they've done that since back in the mid 60's when I wore out the first 2 barrels on Old Meat in the Pot, shooting on my own property with 2 good sized trees less than 10 feet away from the front of the bench, without earmuffs. The back blast off those trees was substantial. :( Now at 74, I've been considering a hearing aid, but can't seem to get my hand to write a check for a decent used car that fits in my ear. >-Dan > > >___ >geda-user mailing list >geda-user@moria.seul.org >http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Certainly there are things in life that money can't buy, But it's very funny -- did you ever try buying them without money? -- Ogden Nash ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Dec 27, 2008, at 2:17 PM, Dan McMahill wrote: >> They can explode pretty violently, so let me tell you a story. >> Back in the >> mid-60's I came across a tube type, mobile cb radio that had to be >> one of the >> few attempts to build one for a 6 volt vehicle system, and >> predated the old >> Johnson whiteface by probably 10 years. My pickup at the time, a >> 52 ford, >> had long since been converted to 12 volts, and I was in the radio, >> on the >> kitchen table, moving wires to convert it to 12 volts. I missed >> one without >> realizing it, and had it running on a 12 volt supply for test. It >> worked >> really really well, talking to the neighbors on a piece of wire >> laying on the >> floor for an antenna. But after about 15 minutes the main filter >> capacitor >> let go, and the top of the can put a quarter sized print in the >> plastered >> ceiling that was about 1/4" deep. I'm glad I wasn't in front of >> it at the > > too funny. My exploding cap story is also related to automotive > electronics. The explosion happened at 2 AM when I was in high > school. > Mom and Dad were not too thrilled about it if I recall correctly. > > Makes a lasting impression though doesn't it? Years ago, I had a friend who used to have some pretty wild parties. Sometimes us geekier types would head down to the basement with him, fairly drunk, and start blowing up small (very small) electrolytic capacitors with a nice power supply that he had set up for exactly that purpose. He had a box of hundreds of capacitors that he'd harvested from old PCBs. It was great fun. :) -Dave -- Dave McGuire Port Charlotte, FL ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
Gene Heskett wrote: > They can explode pretty violently, so let me tell you a story. Back in the > mid-60's I came across a tube type, mobile cb radio that had to be one of the > few attempts to build one for a 6 volt vehicle system, and predated the old > Johnson whiteface by probably 10 years. My pickup at the time, a 52 ford, > had long since been converted to 12 volts, and I was in the radio, on the > kitchen table, moving wires to convert it to 12 volts. I missed one without > realizing it, and had it running on a 12 volt supply for test. It worked > really really well, talking to the neighbors on a piece of wire laying on the > floor for an antenna. But after about 15 minutes the main filter capacitor > let go, and the top of the can put a quarter sized print in the plastered > ceiling that was about 1/4" deep. I'm glad I wasn't in front of it at the too funny. My exploding cap story is also related to automotive electronics. The explosion happened at 2 AM when I was in high school. Mom and Dad were not too thrilled about it if I recall correctly. Makes a lasting impression though doesn't it? -Dan ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Saturday 27 December 2008, Robas, Teodor wrote: >Do not count on this kind of capacitors: > >http://deep-blue.ro/tmp/chinese%20capacitor.jpg > >:)) What a ripoff. No way in hell that would last more than a day, if that long with 50 volts of bias on it, (I'd guess 10 minutes max) and I'd have doubts even the dual can would contain the debris. I take it you got curious when incoming QC said they weren't in spec? BTW, that is a neat opening of the can you did. They can explode pretty violently, so let me tell you a story. Back in the mid-60's I came across a tube type, mobile cb radio that had to be one of the few attempts to build one for a 6 volt vehicle system, and predated the old Johnson whiteface by probably 10 years. My pickup at the time, a 52 ford, had long since been converted to 12 volts, and I was in the radio, on the kitchen table, moving wires to convert it to 12 volts. I missed one without realizing it, and had it running on a 12 volt supply for test. It worked really really well, talking to the neighbors on a piece of wire laying on the floor for an antenna. But after about 15 minutes the main filter capacitor let go, and the top of the can put a quarter sized print in the plastered ceiling that was about 1/4" deep. I'm glad I wasn't in front of it at the time, else I might have been seriously injured. I tried with a 20 oz hammer and could not put a dent that deep in that plaster with it. Putting my meter on the stubs of the cans terminals I found the supply was making a hair over 785 volts, and the can carried a 450 volt label. I cleaned up the mess, replaced the cap, and found the other 2 taps on the transformer that I had missed, and ran that radio till I finally got a transistorized one. But my kids, who were upstairs in bed at the time, have always said, somewhat tongue in cheek, that daddy was shooting at them. :) >___ >geda-user mailing list >geda-user@moria.seul.org >http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) The best diplomat I know is a fully activated phaser bank. -- Scotty ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Dec 27, 2008, at 5:40 AM, Robas, Teodor wrote: > Do not count on this kind of capacitors: > > http://deep-blue.ro/tmp/chinese%20capacitor.jpg > > :)) Oh. My. God. *shudder* That does it...I'm now going to stick EVERY ELECTROLYTIC CAPACITOR I BUY on a bridge before I use it. -Dave -- Dave McGuire Port Charlotte, FL ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
Do not count on this kind of capacitors: http://deep-blue.ro/tmp/chinese%20capacitor.jpg :)) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Friday 26 December 2008, Peter Clifton wrote: >On Fri, 2008-12-26 at 21:00 -0500, gene wrote: >> What does it mean when manufactures specify 'Endurance @ temp' or 'life >> time @ temp'? For example, one company claims: >> Endurance : 105 C 1000 h to 5000h >> Then they further state that after testing at 105C with maximum ripple >> current applied, that when the part is cooled to 20C, it will then meet >> original specs. > >It will still have had its life-time shortened. > >The spec you quote above, AIUI, means that after somewhere between 1000 >and 5000 hours of operation at 105 degrees centigrade, the cap (as >measured at 20 degrees) will be outside of its quoted specifications. > >I can't remember the exact numbers, but derating to lower temperatures >has a stupid factor of lifetime increase. It might even be as much as >double the life-time for every 10 degrees drop in working temperature. > >I guess that merely being at elevated temperature is also lifetime >degrading. You circuit wouldn't need to be on for the electrolyte to be >degrading. As long as the seals hold, the electrolyte won't degrade. Its not the electrolyte that causes most caps to go out of tolerance. The most often seen failure in recent years has not been that of reduced capacity, but sky high ESR. I have seen caps marked 220 uf at 10 volts read 240 uf on a std cap tester, but toss a "capacitor wizard" at them, which tests them with little or no bias, measuring instead their series resistance using a 100khz low level signal, and they will be 5+ ohms at 100khz. Digital circuits go crazy when their supply rails are being bypassed with such a capacitor. What happens when you have such a capacitor in a switching power supply? Easy, those things can put 10 or more amps of ripple currents through such a capacitor, and 5 ohms with 10 amps rms flowing through it equals an explosion as that is 50 watts of power being dissipated in a little can the size of half a joint of your little finger. But it normally doesn't come to that, the voltage surges they allow as the ESR rises above the 2 ohm range usually blow one or more of the switching transistors, followed 50ms later by the line fuse. The culprit of course is the connection between the terminals on the bottom of the can, and the microscopicly thin alu foil the capacitor is made of. A truly 'gas tight' joint simply cannot be done when the foils are so thin you can literally see through them. For best life, keep the caps as cool as you can, and if the capacitance is to be maintained over an extended time period, then the applied bias should be at least 80% of the nameplate rating. Reduced below that, the alu will chemically 'deform', meaning the acid like etching that creates the dielectric film at 10 to 50 times the measured square inches, will eventually smooth enough to cause a loss of the dielectric area, and hence a loss of capacity. The real plates of an electrolytic capacitor are not the two separated alu foils, but the alu oxide coating of the etched foil. The glycol essentially is there for the ride (it has a high dielectric constant and isn't really a great insulator) and its etch restoring properties under sufficient bias. If any of you do service work involving such parts, one of the first things to look for is an alu can with a bulged top (replace it, then measure to confirm :), which tells you the ESR is high and that cap is running hot enough to boil the glycol, possibly blowing the seal in the bottom, but occasionally will split the top open on the scores in the alu can put there for exactly that purpose. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Q: What do you call 50 Microsoft products at the bottom of the ocean? A: A darned good start. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
gene wrote: > What does it mean when manufactures specify 'Endurance @ temp' or 'life > time @ temp'? For example, one company claims: > Endurance : 105 C 1000 h to 5000h > Then they further state that after testing at 105C with maximum ripple > current applied, that when the part is cooled to 20C, it will then meet > original specs. > > Do that mean, that whatever degradation occurs at elevated temperature > and ripple current, that they go back to normal once cooled? I'm just > looking for validation that my understanding is correct. > Most electrolytics are liquid types. Some are solid. The solid ones last an extremely long time, with very little variation in performance. The liquid ones dry out, as they are not hermetically sealed. Their lifetimes are dependent on the drying out rate. The hotter you run them, the faster they dry out. These time vs temperature specs are simply a measure of how fast that drying occurs. Run them hot for just a few weeks, and they are toast. Regards, Steve ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Friday 26 December 2008 21:53, John Luciani wrote: > Usually there is a "Service Life" quoted as number of hours > at rated voltage at a specified core temperature. To > increase the life of the capacitor you decrease the operating > temperature and the operating voltage. For every 10degC > decrease in temperature you get a factor of 2 in life (check the > Arrhenius equation). I don't know the multiplier for voltage. It is a nonlinear relationship. There is an optimum voltage, and it gets worse either higher or lower. Service life can be very bad with near-zero voltages like you get when using electrolytics as coupling caps in op-amp circuits, especially when they can reverse under some signal conditions. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Fri, Dec 26, 2008 at 9:00 PM, gene wrote: > What does it mean when manufactures specify 'Endurance @ temp' or 'life > time @ temp'? For example, one company claims: > Endurance : 105 C 1000 h to 5000h > Then they further state that after testing at 105C with maximum ripple > current applied, that when the part is cooled to 20C, it will then meet > original specs. You may need to dig deeper into the specs or the app notes to verify the vendor terms match. Usually there is a "Service Life" quoted as number of hours at rated voltage at a specified core temperature. To increase the life of the capacitor you decrease the operating temperature and the operating voltage. For every 10degC decrease in temperature you get a factor of 2 in life (check the Arrhenius equation). I don't know the multiplier for voltage. (* jcl *) -- http://www.luciani.org ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
Peter Clifton wrote: > It will still have had its life-time shortened. > > The spec you quote above, AIUI, means that after somewhere between 1000 > and 5000 hours of operation at 105 degrees centigrade, the cap (as > measured at 20 degrees) will be outside of its quoted specifications. > > I can't remember the exact numbers, but derating to lower temperatures > has a stupid factor of lifetime increase. It might even be as much as > double the life-time for every 10 degrees drop in working temperature. > > I guess that merely being at elevated temperature is also lifetime > degrading. You circuit wouldn't need to be on for the electrolyte to be > degrading. > Looking at the data sheet, they claim after being exposed for the test, the device will return to to within +/-20% original value, and the tan-delta will be within 200% original. So the thing gets lossy, I suppose. Is the endurance a cumulative thing? I've got a requirement of around 3.5 A ripple current (although I really need to double check this in simulation), which is a lot of ripple. I planned to use 2 caps in parallel, each with about 1.8A max ripple. But I'm worried that eventually, the things won't do their job. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: electrolytic capacitors
On Fri, 2008-12-26 at 21:00 -0500, gene wrote: > What does it mean when manufactures specify 'Endurance @ temp' or 'life > time @ temp'? For example, one company claims: > Endurance : 105 C 1000 h to 5000h > Then they further state that after testing at 105C with maximum ripple > current applied, that when the part is cooled to 20C, it will then meet > original specs. It will still have had its life-time shortened. The spec you quote above, AIUI, means that after somewhere between 1000 and 5000 hours of operation at 105 degrees centigrade, the cap (as measured at 20 degrees) will be outside of its quoted specifications. I can't remember the exact numbers, but derating to lower temperatures has a stupid factor of lifetime increase. It might even be as much as double the life-time for every 10 degrees drop in working temperature. I guess that merely being at elevated temperature is also lifetime degrading. You circuit wouldn't need to be on for the electrolyte to be degrading. -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
gEDA-user: electrolytic capacitors
What does it mean when manufactures specify 'Endurance @ temp' or 'life time @ temp'? For example, one company claims: Endurance : 105 C 1000 h to 5000h Then they further state that after testing at 105C with maximum ripple current applied, that when the part is cooled to 20C, it will then meet original specs. Do that mean, that whatever degradation occurs at elevated temperature and ripple current, that they go back to normal once cooled? I'm just looking for validation that my understanding is correct. thanks, gene ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
