Let's Take A Vote...
in [Design]
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From: John Devereux on 29 Jul 2010 15:50 John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: > On Thu, 29 Jul 2010 15:10:41 +0100, John Devereux > <john(a)devereux.me.uk> wrote: > >>John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: >> >>> On Thu, 29 Jul 2010 13:38:51 +0300 (EEST), Okkim Atnarivik >>> <Okkim.Atnarivik(a)twentyfout.fi.invalid> wrote: >>> >>>>John Larkin <jjlarkin(a)highnotlandthistechnologypart.com> wrote: >>>>: Do thermals matter to you? Latching relays are fabulous. As analog >>>>: switches, no semiconductor comes close. We recently measured the wiper >>>> >>>> Interestingly, in the LHe temperature OptoMOS switches can be closed >>>>but not opened. Switch-off relies on the charge leaking away from the >>>>MOSFET gate, and this leak obviously freezes. >>> >>> Maybe you're just not waiting long enough. A 2N7002 will keep itself >>> on or off, gate floating, for days. A cryo temps, that might extend to >>> a few million years. I'm impressed that they work at all. >>> >>> Possibly they use a silicon resisor for the pulldown, and the >>> resistance goes way, way up when it's cold. So it might turn off in a >>> few weeks. >>> >>> Optomos SSRs are great signal switches too. I recently blew up a bunch >>> of Clare parts, to find their voltage:current destruct limits. The >>> datasheets are horrible about that. >> >>Yes, pathetic for something clearly intended as an I/O component. I got >>no answer from them either about it. >> >>[...] > > I have some crude point-of-destruction SOAR graphs if you're > interested, on their CPC1008N part. After blowing a bunch up, I > learned that you can look at waveforms and pretty accurately > anticipate second breakdown (or whatever makes them fail) just before > it happens. Plotting graphs is much faster when you don't have to > replace the part every data point, like the civil engineering students > breaking concrete beams. Thanks, but we use the LCA710. "Arc Free with no snubbing circuits" ... "can be used to replace mechanical relays" implied to me that it could switch inductive loads with no snubbing circuits... But of course they don't precisely say that. And they don't, for very long. -- John Devereux
From: John Larkin on 29 Jul 2010 16:40 On Thu, 29 Jul 2010 20:50:01 +0100, John Devereux <john(a)devereux.me.uk> wrote: >John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: > >> On Thu, 29 Jul 2010 15:10:41 +0100, John Devereux >> <john(a)devereux.me.uk> wrote: >> >>>John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: >>> >>>> On Thu, 29 Jul 2010 13:38:51 +0300 (EEST), Okkim Atnarivik >>>> <Okkim.Atnarivik(a)twentyfout.fi.invalid> wrote: >>>> >>>>>John Larkin <jjlarkin(a)highnotlandthistechnologypart.com> wrote: >>>>>: Do thermals matter to you? Latching relays are fabulous. As analog >>>>>: switches, no semiconductor comes close. We recently measured the wiper >>>>> >>>>> Interestingly, in the LHe temperature OptoMOS switches can be closed >>>>>but not opened. Switch-off relies on the charge leaking away from the >>>>>MOSFET gate, and this leak obviously freezes. >>>> >>>> Maybe you're just not waiting long enough. A 2N7002 will keep itself >>>> on or off, gate floating, for days. A cryo temps, that might extend to >>>> a few million years. I'm impressed that they work at all. >>>> >>>> Possibly they use a silicon resisor for the pulldown, and the >>>> resistance goes way, way up when it's cold. So it might turn off in a >>>> few weeks. >>>> >>>> Optomos SSRs are great signal switches too. I recently blew up a bunch >>>> of Clare parts, to find their voltage:current destruct limits. The >>>> datasheets are horrible about that. >>> >>>Yes, pathetic for something clearly intended as an I/O component. I got >>>no answer from them either about it. >>> >>>[...] >> >> I have some crude point-of-destruction SOAR graphs if you're >> interested, on their CPC1008N part. After blowing a bunch up, I >> learned that you can look at waveforms and pretty accurately >> anticipate second breakdown (or whatever makes them fail) just before >> it happens. Plotting graphs is much faster when you don't have to >> replace the part every data point, like the civil engineering students >> breaking concrete beams. > >Thanks, but we use the LCA710. > >"Arc Free with no snubbing circuits" ... "can be used to replace >mechanical relays" implied to me that it could switch inductive loads >with no snubbing circuits... But of course they don't precisely say >that. And they don't, for very long. Gosh, that sounds almost as if someone might not be telling the entire truth. I'm digitizing the voltage and currents around the SSR, 100K samples/second, so I know what's going on. The question was to come up with an algorithm (running on a 100 MHz ARM) that opens things to protect the SSR and some stuff in series, in case the customer decides to hook us up to a 100 volt, zillion amp bus or something. So I had to figure out the destructo-energy of these SSRs and some 1206 resistors. I sort of enjoy blowing things up. John
From: John Larkin on 29 Jul 2010 16:43 On Thu, 29 Jul 2010 14:19:25 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Thu, 29 Jul 2010 09:27:15 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Thu, 29 Jul 2010 11:01:24 -0500, John Fields >><jfields(a)austininstruments.com> wrote: >> >>>On Thu, 29 Jul 2010 07:06:50 -0700, John Larkin >>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Thu, 29 Jul 2010 06:13:05 -0700 (PDT), George Herold >>>><gherold(a)teachspin.com> wrote: >>> >>>>>(I'm just tired of the snipping back and forth... I should have just >>>>>kept my mouth shut and moved on.) >>>>> >>>>>George H. >>>>>> >>>>>> John- Hide quoted text - >>>>>> >>>>>> - Show quoted text - >>>> >>>>Just try injecting technical riffs - braininstorming in public - into >>>>the hen-clucking OT personal rants. Not only does that steer us back >>>>on topic, it annoys the hell out of some people who really deserve >>>>being annoyed. >>> >>>--- >>>Like this one?: >>> >>>I am so sick of grey, white, black, silver, and repulsive >>>pearl-colored cars. You can drive for blocks around here and see >>>nothing but asphalt-colored cars. When I saw that true-red Audi for >>>sale, I had to have it. >>> >>>That Mercedes is a decent shade of red, sort of arterial blood color. >>>I've started to see a few new cars on the street that are actual >>>colors, not just midnight blue or mud red, but *colors*. Maybe things >>>are turning around. >>> >>>Those Germans sure know how to make cars. 0-60 in 3.7 seconds isn't >>>bad at all. That's 0.75 Gs, if I did the math right. >>> >>>John >>> >>> >>>or this one?: >>> >>>Nobody is going to do anything serious about CO2. And maybe we >>>shouldn't anyhow. >>> >>>This is serious >>> >>>http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2010/07/28/MN5H1EK6BV.DTL >>> >>>and we *can* do something about it. >>> >>>John >> >>Absolutely. These are real-world objective issues, > >--- >What's objective about: > >"I am so sick of grey, white, black, silver, and repulsive >pearl-colored cars. You can drive for blocks around here and see >nothing but asphalt-colored cars. When I saw that true-red Audi for >sale, I had to have it. > >That Mercedes is a decent shade of red, sort of arterial blood color. >I've started to see a few new cars on the street that are actual >colors, not just midnight blue or mud red, but *colors*. Maybe things >are turning around." ??? > >Plus, it certainly seems to be a contradiction of your suggestion to: > >"Just try injecting technical riffs - braininstorming in public - into >the hen-clucking OT personal rants. Not only does that steer us back >on topic, it annoys the hell out of some people who really deserve >being annoyed." >--- > >>about *things*, >>likely of interest to many engineers, especially as diversions from >>the psychotic personality-issue cluckings of bizarre old farts. > >--- >Regardless of your penchant for posting off-topic material here, >from your negative comments re. things "off topic" one would certainly >think you'd be aware that this here newsgroup is for the purpose of >discussing electronics design/designs, (hard to miss since >science.electronics.design is its name) and that you'd have the >courtesy of posting your hen-clucking personal rants to a newsgroup >where they'd be on-topic. Be a paragon and say something interesting about electronics. Or something interesting, period. John
From: Grant on 29 Jul 2010 18:01 On Thu, 29 Jul 2010 13:40:40 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Thu, 29 Jul 2010 20:50:01 +0100, John Devereux ><john(a)devereux.me.uk> wrote: > >>John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: >> >>> On Thu, 29 Jul 2010 15:10:41 +0100, John Devereux >>> <john(a)devereux.me.uk> wrote: >>> >>>>John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: >>>> >>>>> On Thu, 29 Jul 2010 13:38:51 +0300 (EEST), Okkim Atnarivik >>>>> <Okkim.Atnarivik(a)twentyfout.fi.invalid> wrote: >>>>> >>>>>>John Larkin <jjlarkin(a)highnotlandthistechnologypart.com> wrote: >>>>>>: Do thermals matter to you? Latching relays are fabulous. As analog >>>>>>: switches, no semiconductor comes close. We recently measured the wiper >>>>>> >>>>>> Interestingly, in the LHe temperature OptoMOS switches can be closed >>>>>>but not opened. Switch-off relies on the charge leaking away from the >>>>>>MOSFET gate, and this leak obviously freezes. >>>>> >>>>> Maybe you're just not waiting long enough. A 2N7002 will keep itself >>>>> on or off, gate floating, for days. A cryo temps, that might extend to >>>>> a few million years. I'm impressed that they work at all. >>>>> >>>>> Possibly they use a silicon resisor for the pulldown, and the >>>>> resistance goes way, way up when it's cold. So it might turn off in a >>>>> few weeks. >>>>> >>>>> Optomos SSRs are great signal switches too. I recently blew up a bunch >>>>> of Clare parts, to find their voltage:current destruct limits. The >>>>> datasheets are horrible about that. >>>> >>>>Yes, pathetic for something clearly intended as an I/O component. I got >>>>no answer from them either about it. >>>> >>>>[...] >>> >>> I have some crude point-of-destruction SOAR graphs if you're >>> interested, on their CPC1008N part. After blowing a bunch up, I >>> learned that you can look at waveforms and pretty accurately >>> anticipate second breakdown (or whatever makes them fail) just before >>> it happens. Plotting graphs is much faster when you don't have to >>> replace the part every data point, like the civil engineering students >>> breaking concrete beams. >> >>Thanks, but we use the LCA710. >> >>"Arc Free with no snubbing circuits" ... "can be used to replace >>mechanical relays" implied to me that it could switch inductive loads >>with no snubbing circuits... But of course they don't precisely say >>that. And they don't, for very long. > >Gosh, that sounds almost as if someone might not be telling the entire >truth. > >I'm digitizing the voltage and currents around the SSR, 100K >samples/second, so I know what's going on. The question was to come up >with an algorithm (running on a 100 MHz ARM) that opens things to >protect the SSR and some stuff in series, in case the customer decides >to hook us up to a 100 volt, zillion amp bus or something. So I had to >figure out the destructo-energy of these SSRs and some 1206 resistors. >I sort of enjoy blowing things up. Besides, nothing like the 'admiral's test' to actually know what's going on :) I'm surprised more people don't go for it. I think that's why we have so much easily damaged equipment about these days. I'm looking at a little rs232 interface module that blew up -- they connect a 78L05 regulator direct to a 24V traction battery charging connector with nothing more than a series fuse, no spike or negative voltage protection. The type of plug used can allow momentary reverse voltage touch -- not enough to blow the fuse in this case, enough to blow a chip. Replacement cost $180, imported. So I'll add some protection circuitry to the new one. Doubt I can fix the blown one, no circuit, unless only the regulator is gone. All of it tiny smd... Grant.
From: krw on 29 Jul 2010 18:28
On Thu, 29 Jul 2010 10:12:19 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Thu, 29 Jul 2010 11:25:59 -0500, John Fields ><jfields(a)austininstruments.com> wrote: > >>On Thu, 29 Jul 2010 07:08:58 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Wed, 28 Jul 2010 22:35:28 -0700, Robert Baer >>><robertbaer(a)localnet.com> wrote: >>> >>>>John Larkin wrote: >>>>> On Wed, 28 Jul 2010 00:52:53 -0700, Robert Baer >>>>> <robertbaer(a)localnet.com> wrote: >>>>> >>>>>> John Fields wrote: >>>>>>> On Tue, 27 Jul 2010 07:01:58 -0700, John Larkin >>>>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> >>>>>>>> On Tue, 27 Jul 2010 04:00:22 -0500, John Fields >>>>>>>> <jfields(a)austininstruments.com> wrote: >>>>>>>> >>>>>>>> >>>>>>>>>> It has to do with >>>>>>>>>> getting SI units right. Did you ever read the wiki piece on >>>>>>>>>> dimensional analysis? Do you think it is smoke and mirrors? >>>>>>>>>> >>>>>>>>>> So, where did I say that charges can't generate forces? If you can't >>>>>>>>>> find such a statement, YOU are the one with emotions clouding your >>>>>>>>>> reason. >>>>>>>>> --- >>>>>>>>> Nonsense. >>>>>>>>> >>>>>>>>> All it means is that its location has slipped my mind, that the >>>>>>>>> message has been deleted or, who knows??? >>>>>>>> Who knows??? I know. You are deluded or just a liar. I would never say >>>>>>>> anything so silly. >>>>>>> --- >>>>>>> You would, you have, and you will again, so you're the liar. >>>>>>> >>>>>>> "Latching relays have infinite gain." is a pretty silly thing to say, >>>>>>> yes? >>>>>>> >>>>>>> >>>>>>> JF >>>>>>> >>>>>> I think i "made a case" that the "gain" was not too hot, using rough >>>>>> numbers for input power to switch states, and power handling capability. >>>>>> For an infinite "gain", either the power to switch states must be >>>>>> zero, and/or the power handling capability must be infinite. >>>>>> Clearly, NEITHER exists. >>>>> >>>>> Power gain is Pload/(Pcoil*DutyCycle), where Dutycycle is the fraction >>>>> of time that the coil is energized. In plain English, power gain is >>>>> averaged load power divided by averaged coil power. That has no upper >>>>> bound as duty cycle approaches zero. In, say, a home thermostat that >>>>> uses one AA battery, Dutycycle might be a few tens of PPM, which is >>>>> why the battery will last a year or two. Probably the clock/LCD run >>>>> the battery down more than the relay does. >>>>> >>>>> So the argument devolves to whether a number that is unboundedly large >>>>> can be referred to as "infinite." Go for it. >>>>> >>>>> John >>>>> >>>>> >>>> By your own statement, you admit that the duty cycle IS NOT ZERO, and >>>>therefore there IS a bound. >>> >>>What's the bound of 1/x as x approaches zero? Name a number. >> >>--- >>There is no bound, but it'll never become infinite until x = 0 >> >>However, in the case of a form "A" latching relay, which is what we're >>talking about but which you keep trying to sidetrack, x can never >>become zero, so the gain of the relay will always be less than >>infinite. >>--- >> >>>> And "duty cycle" does not cut it; if so, one could take a very large >>>>(latching, if that "helps") relay and operate it *once* using its >>>>required 200KW of power, to control one microwatt of load >>> >>>Or one kilowatt >>> >>> - and >>>>"therefore" have an absurdly large "gain" based on the "duty cycle" of >>>>almost zero. >>> >>> >>>Thanks. Finally someone is beginning to see my point. >> >>--- >>You're really not making a point John, all you're trying to do is >>ameliorate an earlier erroneous statement by saying,: "Well, geez, as >>long as the duty cycle's pretty small the gain will be pretty close to >>infinite." > >OK, introduce some different electronics topic, if you know of one. We could sit around and praise the 555. |