Bad resistors
in [Design]
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From: DrParnassus on 22 Jun 2010 21:36 On Tue, 22 Jun 2010 17:08:34 -0700 (PDT), Richard Henry <pomerado(a)hotmail.com> wrote: >On Jun 22, 4:54�pm, DrParnassus <DrParnas...(a)hereforlongtime.org> >wrote: >> On Tue, 22 Jun 2010 21:51:47 GMT, Jan Panteltje >> >> <pNaonStpealm...(a)yahoo.com> wrote: >> >Got 10 resistors on tape marked 2M7. >> >Used one, circuit did not work right. >> >Took some testing ... before I measured the resistors. >> >Of the 10 several are 620 k and not 2M7. >> >Bought fromwww.voti.nl, so beware. >> >All are marked with the right color code for 2M7. >> >> >New to me :-) >> >> � A normal handheld DVM barely measures 1MOhm correctly so anything up >> there and over will not likely be easily measured with cheap handhelds. > >Apparently some read correctly. Very few.
From: DrParnassus on 22 Jun 2010 21:43 On Tue, 22 Jun 2010 17:59:40 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Tue, 22 Jun 2010 16:54:15 -0700, DrParnassus ><DrParnassus(a)hereforlongtime.org> wrote: > >>On Tue, 22 Jun 2010 21:51:47 GMT, Jan Panteltje >><pNaonStpealmtje(a)yahoo.com> wrote: >> >>>Got 10 resistors on tape marked 2M7. >>>Used one, circuit did not work right. >>>Took some testing ... before I measured the resistors. >>>Of the 10 several are 620 k and not 2M7. >>>Bought from www.voti.nl, so beware. >>>All are marked with the right color code for 2M7. >>> >>>New to me :-) >> >> A normal handheld DVM barely measures 1MOhm correctly so anything up >>there and over will not likely be easily measured with cheap handhelds. > > >AlwaysWrong! >AlwaysWrong! >AlwaysWrong! > >1.1 meg and 4.7 meg, 5% resistors read... > >Fluke 8845A benchtop 1.08220 M 4.6390 M > >Fluke 87 handheld 1.083 M 4.64 M > >Fluke 75 handheld 1.084 M 4.66 M > > >The last two haven't been calibrated in years. > >The biggest problem is the terrible TC of the carbon film resistors. > >I'll try a cheap Extech when I get home. > >AlwaysWrong! >AlwaysWrong! >AlwaysWrong! > > >John > Sorry, John. Where I come from accuracy matters, and an inaccurate reading is no reading at all. And no, there is absolutely no way to guarantee the accuracy of the reading ever, under any circumstance at that end of the range, past 1Mohm. even finger oils on the part that you DID just touch, makes a difference. And yeas, I know that you are too stupid to have thought about that aspect. The calibration houses will not even cal one at that end of the range, and they'll tell you so.
From: John Larkin on 22 Jun 2010 21:50 On Tue, 22 Jun 2010 17:59:40 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Tue, 22 Jun 2010 16:54:15 -0700, DrParnassus ><DrParnassus(a)hereforlongtime.org> wrote: > >>On Tue, 22 Jun 2010 21:51:47 GMT, Jan Panteltje >><pNaonStpealmtje(a)yahoo.com> wrote: >> >>>Got 10 resistors on tape marked 2M7. >>>Used one, circuit did not work right. >>>Took some testing ... before I measured the resistors. >>>Of the 10 several are 620 k and not 2M7. >>>Bought from www.voti.nl, so beware. >>>All are marked with the right color code for 2M7. >>> >>>New to me :-) >> >> A normal handheld DVM barely measures 1MOhm correctly so anything up >>there and over will not likely be easily measured with cheap handhelds. > > >AlwaysWrong! >AlwaysWrong! >AlwaysWrong! > >1.1 meg and 4.7 meg, 5% resistors read... > >Fluke 8845A benchtop 1.08220 M 4.6390 M > >Fluke 87 handheld 1.083 M 4.64 M > >Fluke 75 handheld 1.084 M 4.66 M > > >The last two haven't been calibrated in years. > >The biggest problem is the terrible TC of the carbon film resistors. > >I'll try a cheap Extech when I get home. > >AlwaysWrong! >AlwaysWrong! >AlwaysWrong! > > >John > Extech model 26: 1.088, 4.68. It's pretty cold, been soaking in the garage for a year or so. It's a pretty nice meter, for a cheapie: it does t/c temperature, capacitance, frequency, duty cycle. Oh, did I mention that you're AlwaysWrong? John
From: Spehro Pefhany on 22 Jun 2010 21:52 On Tue, 22 Jun 2010 21:51:47 GMT, the renowned Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >Got 10 resistors on tape marked 2M7. >Used one, circuit did not work right. >Took some testing ... before I measured the resistors. >Of the 10 several are 620 k and not 2M7. >Bought from www.voti.nl, so beware. >All are marked with the right color code for 2M7. > >New to me :-) Vhat is Wouter up to? Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
From: John Larkin on 22 Jun 2010 23:04
On Tue, 22 Jun 2010 18:43:30 -0700, DrParnassus <DrParnassus(a)hereforlongtime.org> wrote: >On Tue, 22 Jun 2010 17:59:40 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Tue, 22 Jun 2010 16:54:15 -0700, DrParnassus >><DrParnassus(a)hereforlongtime.org> wrote: >> >>>On Tue, 22 Jun 2010 21:51:47 GMT, Jan Panteltje >>><pNaonStpealmtje(a)yahoo.com> wrote: >>> >>>>Got 10 resistors on tape marked 2M7. >>>>Used one, circuit did not work right. >>>>Took some testing ... before I measured the resistors. >>>>Of the 10 several are 620 k and not 2M7. >>>>Bought from www.voti.nl, so beware. >>>>All are marked with the right color code for 2M7. >>>> >>>>New to me :-) >>> >>> A normal handheld DVM barely measures 1MOhm correctly so anything up >>>there and over will not likely be easily measured with cheap handhelds. >> >> >>AlwaysWrong! >>AlwaysWrong! >>AlwaysWrong! >> >>1.1 meg and 4.7 meg, 5% resistors read... >> >>Fluke 8845A benchtop 1.08220 M 4.6390 M >> >>Fluke 87 handheld 1.083 M 4.64 M >> >>Fluke 75 handheld 1.084 M 4.66 M >> >> >>The last two haven't been calibrated in years. >> >>The biggest problem is the terrible TC of the carbon film resistors. >> >>I'll try a cheap Extech when I get home. >> >>AlwaysWrong! >>AlwaysWrong! >>AlwaysWrong! >> >> >>John >> > > Sorry, John. Where I come from accuracy matters, and an inaccurate >reading is no reading at all. What are you talking about? The spread on my measurements is under half a per cent. The benchtop agrees with the '87 to a tenth of a per cent at 1M and 5M. > > And no, there is absolutely no way to guarantee the accuracy of the >reading ever, under any circumstance at that end of the range, past >1Mohm. even finger oils on the part that you DID just touch, makes a >difference. And yeas, I know that you are too stupid to have thought >about that aspect. > > The calibration houses will not even cal one at that end of the range, >and they'll tell you so. How perfectly idiotic of you. I routinely make measurements up to 1 Tohm. For the innumerate out there, that's a million megohms. My Keithley 610C will measure up to 1e14 ohms, 100 million million ohms in math-phobic terms. I buy 1 Tohm 5% 0805 resistors and they read within about 5%. Fingerprints are no problem at 1 Gohm (that's a thousand megohms to you.) Well, depending on what's on your fingers. AlwaysWrong. Always. John |