On Tue, 19 Sep 2017 18:55:31 GMT, Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> wrote:>On a sunny day (Tue, 19 Sep 2017 11:02:38 -0700) it happened John Larkin ><jjlarkin@highland_snip_technology.com> wrote in ><fom2sctjgp0boousiphreq9j7l7tcrtcgk@4ax.com>: > >>OK, I'm ready to blow up some resistors, as soon as UPS arrives. >> >>https://www.dropbox.com/s/u2078h7upn81q10/Z420_3.JPG?raw=1 >> >>That should do numbers like 300 amps, 80 joules, 50 volts. > >Why blow anything up?To see if the part specs are real, and to see how much margin we have. Resistor failures might have serious consequences to some of our customers. I have seen wirewound resistors die from thermal fatigue, well within their power specs, so I might pulse them hard for a couple of months and see if they fail that way.>I made this to test 30C lipo batteries, 4 x 1 Ohm 100 W: > http://panteltje.com/pub/power_resistors_IMG_6291.JPG > http://panteltje.com/pub/big_heatsink_IMG_6292.JPG >combine them anyway you want. >99 cent each: > http://www.ebay.com/itm/111969905996We have seen those metal-case wirewounds fail from fatigue. We replaced them with these, on heat sinks: https://www.dropbox.com/s/0hbgfkvvg3xf6cg/Welwyn.JPG?raw=1 Of course, that's not a big issue on a one-off test rig. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
exploding wirewound resistors
Started by ●September 15, 2017
Reply by ●September 19, 20172017-09-19
Reply by ●September 19, 20172017-09-19
On Tue, 19 Sep 2017 19:10:40 GMT, Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote:>On a sunny day (Tue, 19 Sep 2017 12:03:13 -0700) it happened boB ><boB@k7iq.com> wrote in <ocq2sc92k5cs7ak654q2kv5bmpeb6t2eth@4ax.com>: > >>On Mon, 18 Sep 2017 20:37:28 -0700, John Larkin >><jjlarkin@highlandtechnology.com> wrote: >> >>>On Mon, 18 Sep 2017 12:43:08 -0500, "Tim Williams" >>><tmoranwms@gmail.com> wrote: >>> >>>>"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message >>>>news:g9jurc10cn36es7msu75e50iqgbh92f9fa@4ax.com... >>>>> Did you notice, on my sketch, the parts labeled CURRENT LIMITERS ? >>>>> >>>>>> >>>>>>And the manufacturer, let's not leave them out. Y'think they might know a >>>>>>thing or two about their product? >>>>> >>>>> Why are you being such a smarmy jerk? >>>>> >>>> >>>>Why are you conflating CURRENT LIMITERS with screwdrivers? >>>> >>>> >>>>"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message >>>>news:617trchvnvaprp8rhqf0lnucs3dnb5fveh@4ax.com... >>>>> I don't think so. You can fully charge an electrolytic cap and then >>>>> short it with a screwdriver (or a flashtube) and it doesn't seem to >>>>> mind. >>>> >>>>You wrote this, didn't you? >>>> >>>>Tim >>> >>>You aren't worth reading. >> >>John's got to be kidding ? >> >>You both contrbute worthy information here >> >>boB > >Actually in the flash tube designs I did I used a small inductor in series to limit the current. >Else BAD THINGS can happen. >Damage to caps, or flashtubes? -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●September 19, 20172017-09-19
On a sunny day (Tue, 19 Sep 2017 12:17:45 -0700) it happened John Larkin <jjlarkin@highland_snip_technology.com> wrote in <urq2sctam2qvtbnj20nsj2fvetthjeq1cr@4ax.com>:>On Tue, 19 Sep 2017 18:55:31 GMT, Jan Panteltje ><pNaOnStPeAlMtje@yahoo.com> wrote: > >>On a sunny day (Tue, 19 Sep 2017 11:02:38 -0700) it happened John Larkin >><jjlarkin@highland_snip_technology.com> wrote in >><fom2sctjgp0boousiphreq9j7l7tcrtcgk@4ax.com>: >> >>>OK, I'm ready to blow up some resistors, as soon as UPS arrives. >>> >>>https://www.dropbox.com/s/u2078h7upn81q10/Z420_3.JPG?raw=1 >>> >>>That should do numbers like 300 amps, 80 joules, 50 volts. >> >>Why blow anything up? > >To see if the part specs are real, and to see how much margin we have. >Resistor failures might have serious consequences to some of our >customers. > >I have seen wirewound resistors die from thermal fatigue, well within >their power specs, so I might pulse them hard for a couple of months >and see if they fail that way. > > > > >>I made this to test 30C lipo batteries, 4 x 1 Ohm 100 W: >> http://panteltje.com/pub/power_resistors_IMG_6291.JPG >> http://panteltje.com/pub/big_heatsink_IMG_6292.JPG >>combine them anyway you want. >>99 cent each: >> http://www.ebay.com/itm/111969905996 > > >We have seen those metal-case wirewounds fail from fatigue. We >replaced them with these, on heat sinks: > >https://www.dropbox.com/s/0hbgfkvvg3xf6cg/Welwyn.JPG?raw=1 > >Of course, that's not a big issue on a one-off test rig.Yes that is nice stuff, but those cemented ones as I use are very sturdy, although indeed in old TV sets (tube age) where those were used in series with heaters or power supply for example, they were a common fault source. At least they are explosion protected (by the alu casing). When your PCB thing explodes the parts will fly all over the place? Just to be nit-picking..
Reply by ●September 19, 20172017-09-19
On a sunny day (Tue, 19 Sep 2017 12:22:20 -0700) it happened John Larkin <jjlarkin@highland_snip_technology.com> wrote in <mgr2scpu1pca1tda4n6jkt9mllgpiils4q@4ax.com>:>On Tue, 19 Sep 2017 19:10:40 GMT, Jan Panteltje ><pNa0nStpealmtje@yahoo.com> wrote: > >>On a sunny day (Tue, 19 Sep 2017 12:03:13 -0700) it happened boB >><boB@k7iq.com> wrote in <ocq2sc92k5cs7ak654q2kv5bmpeb6t2eth@4ax.com>: >> >>>On Mon, 18 Sep 2017 20:37:28 -0700, John Larkin >>><jjlarkin@highlandtechnology.com> wrote: >>> >>>>On Mon, 18 Sep 2017 12:43:08 -0500, "Tim Williams" >>>><tmoranwms@gmail.com> wrote: >>>> >>>>>"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message >>>>>news:g9jurc10cn36es7msu75e50iqgbh92f9fa@4ax.com... >>>>>> Did you notice, on my sketch, the parts labeled CURRENT LIMITERS ? >>>>>> >>>>>>> >>>>>>>And the manufacturer, let's not leave them out. Y'think they might know a >>>>>>>thing or two about their product? >>>>>> >>>>>> Why are you being such a smarmy jerk? >>>>>> >>>>> >>>>>Why are you conflating CURRENT LIMITERS with screwdrivers? >>>>> >>>>> >>>>>"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message >>>>>news:617trchvnvaprp8rhqf0lnucs3dnb5fveh@4ax.com... >>>>>> I don't think so. You can fully charge an electrolytic cap and then >>>>>> short it with a screwdriver (or a flashtube) and it doesn't seem to >>>>>> mind. >>>>> >>>>>You wrote this, didn't you? >>>>> >>>>>Tim >>>> >>>>You aren't worth reading. >>> >>>John's got to be kidding ? >>> >>>You both contrbute worthy information here >>> >>>boB >> >>Actually in the flash tube designs I did I used a small inductor in series to limit the current. >>Else BAD THINGS can happen. >> > >Damage to caps, or flashtubes?Probably both, I remember (eighties last century) working through those flash tube (BIG ONES) datasheets to get it right, was for a flash in top of a tower.
Reply by ●September 19, 20172017-09-19
On Tue, 19 Sep 2017 19:41:09 GMT, Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote:>On a sunny day (Tue, 19 Sep 2017 12:17:45 -0700) it happened John Larkin ><jjlarkin@highland_snip_technology.com> wrote in ><urq2sctam2qvtbnj20nsj2fvetthjeq1cr@4ax.com>: > >>On Tue, 19 Sep 2017 18:55:31 GMT, Jan Panteltje >><pNaOnStPeAlMtje@yahoo.com> wrote: >> >>>On a sunny day (Tue, 19 Sep 2017 11:02:38 -0700) it happened John Larkin >>><jjlarkin@highland_snip_technology.com> wrote in >>><fom2sctjgp0boousiphreq9j7l7tcrtcgk@4ax.com>: >>> >>>>OK, I'm ready to blow up some resistors, as soon as UPS arrives. >>>> >>>>https://www.dropbox.com/s/u2078h7upn81q10/Z420_3.JPG?raw=1 >>>> >>>>That should do numbers like 300 amps, 80 joules, 50 volts. >>> >>>Why blow anything up? >> >>To see if the part specs are real, and to see how much margin we have. >>Resistor failures might have serious consequences to some of our >>customers. >> >>I have seen wirewound resistors die from thermal fatigue, well within >>their power specs, so I might pulse them hard for a couple of months >>and see if they fail that way. >> >> >> >> >>>I made this to test 30C lipo batteries, 4 x 1 Ohm 100 W: >>> http://panteltje.com/pub/power_resistors_IMG_6291.JPG >>> http://panteltje.com/pub/big_heatsink_IMG_6292.JPG >>>combine them anyway you want. >>>99 cent each: >>> http://www.ebay.com/itm/111969905996 >> >> >>We have seen those metal-case wirewounds fail from fatigue. We >>replaced them with these, on heat sinks: >> >>https://www.dropbox.com/s/0hbgfkvvg3xf6cg/Welwyn.JPG?raw=1 >> >>Of course, that's not a big issue on a one-off test rig. > >Yes that is nice stuff, but those cemented ones as I use are >very sturdy, although indeed in old TV sets (tube age) where those >were used in series with heaters or power supply for example, >they were a common fault source.Yes, they work a lot better with steady power dissipation. Spikes of heat break them. The app where our big ones failed, they were acting as sort of a pre-regulator to a big power supply, bang-bang mode.>At least they are explosion protected (by the alu casing). >When your PCB thing explodes the parts will fly all over the place? >Just to be nit-picking..It's only 80 joules so I expect superficial wounds. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●September 19, 20172017-09-19
On Tue, 19 Sep 2017 11:02:38 -0700, John Larkin <jjlarkin@highland_snip_technology.com> wrote:>On Fri, 15 Sep 2017 13:16:39 -0700, John Larkin ><jjlarkin@highland_snip_technology.com> wrote: > >> >> >>Lots of people make parts like this: >> >>https://www.digikey.com/product-detail/en/bourns-inc/PWR5322WR250JE/PWR5322WR250JETR-ND/2022962 >> >>The overload specs are almost always 5x rated power for 5 seconds, so >>a 3 watt part can absorb 15 joules in that time. I wonder what happens >>for shorter time overloads? Constant joules? >> >>Has anyone experimented with stressing this sort of small wirewound >>resistor? >> >>I'll probably order some and blow them up. We'll be using low ohms, >>0.2 maybe, so we'll need a lot of current. There's a car repair place >>and a motorcycle shop on our block, so maybe I could buy or borrow a >>battery. For pure fast joules, I could just discharge some big >>electrolytics. > >OK, I'm ready to blow up some resistors, as soon as UPS arrives. > >https://www.dropbox.com/s/u2078h7upn81q10/Z420_3.JPG?raw=1 > >That should do numbers like 300 amps, 80 joules, 50 volts.We got some TE 3-watt parts, 0.33R, SMW3 series. I kept increasing joules per shot. At 10.8J, the resistor went POP but kept working. The case has a small crack on top and little puffs of smoke came out every pulse. It seems to have run out of smoke now. Still works. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●September 19, 20172017-09-19
On Tue, 19 Sep 2017 19:43:49 GMT, Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote:>On a sunny day (Tue, 19 Sep 2017 12:22:20 -0700) it happened John Larkin ><jjlarkin@highland_snip_technology.com> wrote in ><mgr2scpu1pca1tda4n6jkt9mllgpiils4q@4ax.com>: > >>On Tue, 19 Sep 2017 19:10:40 GMT, Jan Panteltje >><pNa0nStpealmtje@yahoo.com> wrote: >> >>>On a sunny day (Tue, 19 Sep 2017 12:03:13 -0700) it happened boB >>><boB@k7iq.com> wrote in <ocq2sc92k5cs7ak654q2kv5bmpeb6t2eth@4ax.com>: >>> >>>>On Mon, 18 Sep 2017 20:37:28 -0700, John Larkin >>>><jjlarkin@highlandtechnology.com> wrote: >>>> >>>>>On Mon, 18 Sep 2017 12:43:08 -0500, "Tim Williams" >>>>><tmoranwms@gmail.com> wrote: >>>>> >>>>>>"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message >>>>>>news:g9jurc10cn36es7msu75e50iqgbh92f9fa@4ax.com... >>>>>>> Did you notice, on my sketch, the parts labeled CURRENT LIMITERS ? >>>>>>> >>>>>>>> >>>>>>>>And the manufacturer, let's not leave them out. Y'think they might know a >>>>>>>>thing or two about their product? >>>>>>> >>>>>>> Why are you being such a smarmy jerk? >>>>>>> >>>>>> >>>>>>Why are you conflating CURRENT LIMITERS with screwdrivers? >>>>>> >>>>>> >>>>>>"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message >>>>>>news:617trchvnvaprp8rhqf0lnucs3dnb5fveh@4ax.com... >>>>>>> I don't think so. You can fully charge an electrolytic cap and then >>>>>>> short it with a screwdriver (or a flashtube) and it doesn't seem to >>>>>>> mind. >>>>>> >>>>>>You wrote this, didn't you? >>>>>> >>>>>>Tim >>>>> >>>>>You aren't worth reading. >>>> >>>>John's got to be kidding ? >>>> >>>>You both contrbute worthy information here >>>> >>>>boB >>> >>>Actually in the flash tube designs I did I used a small inductor in series to limit the current. >>>Else BAD THINGS can happen. >>> >> >>Damage to caps, or flashtubes? > >Probably both, I remember (eighties last century) working >through those flash tube (BIG ONES) datasheets to get it right, >was for a flash in top of a tower.I worked on a kilojoule flash once. It was a couple hundred pounds of oil caps and power supply on a cart. It was used to develop Kalvar film, which is (or was) diazo stuff embedded in plastic. A big light flash makes microbubbles, which scatters light. Geez, I have done so much weird stuff. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●September 20, 20172017-09-20
On a sunny day (Tue, 19 Sep 2017 12:48:27 -0700) it happened John Larkin <jjlarkin@highland_snip_technology.com> wrote in <tts2scdlr3bgd9tqnajtv26d5n01rg4247@4ax.com>:>>Yes that is nice stuff, but those cemented ones as I use are >>very sturdy, although indeed in old TV sets (tube age) where those >>were used in series with heaters or power supply for example, >>they were a common fault source. > >Yes, they work a lot better with steady power dissipation. Spikes of >heat break them. The app where our big ones failed, they were acting >as sort of a pre-regulator to a big power supply, bang-bang mode. > >>At least they are explosion protected (by the alu casing). >>When your PCB thing explodes the parts will fly all over the place? >>Just to be nit-picking.. > >It's only 80 joules so I expect superficial wounds.What had been bothering me is minuscule pieces of metal flying about and shorting other critical electronics, perhaps control circuits or some overload protection. I have many modules from ebay that when inspected with a magnifying glass, show minuscule pieces of solder stuck to the board, when that comes lose and starts traveling, then no telling what can happen. Since that day I inspect every board with a magnifying glass. Jan Panteltje Low land Technology pick-a-second timing> >-- > >John Larkin Highland Technology, Inc >picosecond timing precision measurement > >jlarkin att highlandtechnology dott com >http://www.highlandtechnology.com > >
Reply by ●September 20, 20172017-09-20
On 09/19/2017 05:55 PM, John Larkin wrote:> On Tue, 19 Sep 2017 11:02:38 -0700, John Larkin > <jjlarkin@highland_snip_technology.com> wrote: > >> On Fri, 15 Sep 2017 13:16:39 -0700, John Larkin >> <jjlarkin@highland_snip_technology.com> wrote: >> >>> >>> >>> Lots of people make parts like this: >>> >>> https://www.digikey.com/product-detail/en/bourns-inc/PWR5322WR250JE/PWR5322WR250JETR-ND/2022962 >>> >>> The overload specs are almost always 5x rated power for 5 seconds, so >>> a 3 watt part can absorb 15 joules in that time. I wonder what happens >>> for shorter time overloads? Constant joules? >>> >>> Has anyone experimented with stressing this sort of small wirewound >>> resistor? >>> >>> I'll probably order some and blow them up. We'll be using low ohms, >>> 0.2 maybe, so we'll need a lot of current. There's a car repair place >>> and a motorcycle shop on our block, so maybe I could buy or borrow a >>> battery. For pure fast joules, I could just discharge some big >>> electrolytics. >> >> OK, I'm ready to blow up some resistors, as soon as UPS arrives. >> >> https://www.dropbox.com/s/u2078h7upn81q10/Z420_3.JPG?raw=1 >> >> That should do numbers like 300 amps, 80 joules, 50 volts. > > We got some TE 3-watt parts, 0.33R, SMW3 series. I kept increasing > joules per shot. At 10.8J, the resistor went POP but kept working. The > case has a small crack on top and little puffs of smoke came out every > pulse. > > It seems to have run out of smoke now. Still works.There's also non-magic smoke. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●September 20, 20172017-09-20
On Wed, 20 Sep 2017 07:48:29 GMT, Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> wrote:>On a sunny day (Tue, 19 Sep 2017 12:48:27 -0700) it happened John Larkin ><jjlarkin@highland_snip_technology.com> wrote in ><tts2scdlr3bgd9tqnajtv26d5n01rg4247@4ax.com>: > >>>Yes that is nice stuff, but those cemented ones as I use are >>>very sturdy, although indeed in old TV sets (tube age) where those >>>were used in series with heaters or power supply for example, >>>they were a common fault source. >> >>Yes, they work a lot better with steady power dissipation. Spikes of >>heat break them. The app where our big ones failed, they were acting >>as sort of a pre-regulator to a big power supply, bang-bang mode. >> >>>At least they are explosion protected (by the alu casing). >>>When your PCB thing explodes the parts will fly all over the place? >>>Just to be nit-picking.. >> >>It's only 80 joules so I expect superficial wounds. > >What had been bothering me is minuscule pieces of metal flying about and shorting other critical electronics, >perhaps control circuits or some overload protection. >I have many modules from ebay that when inspected with a magnifying glass, >show minuscule pieces of solder stuck to the board, >when that comes lose and starts traveling, then no telling what can happen. >Since that day I inspect every board with a magnifying glass. > >Jan Panteltje Low land Technology >pick-a-second timingIt's fun and pays the bills. -- John Larkin Highland Technology, Inc lunatic fringe electronics
