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Re: ESR meters (again)
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Bob Albert
ESR and D are somewhat independent.? If ESR is low, D can still be high due to dielectric problems.? And high ESR isn't always a problem.
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I guess there is no all encompassing parameter that can characterize a capacitor.? Much depends on the frequency and other aspects of the application. Further, small capacitors can indicate high ESR when that isn't the case; it depends on the frequency.? In other words, if the capacitive reactance at the test frequency is of the order of magnitude of the ESR, ESR readings are worthless.? The best test is to run a frequency sweep.? Well, maybe the best test is to install and use the capacitor and see if it works. Sometimes there will be an intermittent, say a loose termination inside the DUT that shows up occasionally. Series inductance is important as well, especially at higher frequencies.? This includes lead inductance and internal interconnections.? Electrolytic capacitors have their own set of problems, including occasional punching through of the electrolyte that only shows up at higher voltages.? So a voltage test is called for sometimes. For tuning capacitors we also must deal with temperature coefficient of capacitance, something only measurable by varying the temperature. And on and on.... Bob On Saturday, March 26, 2016 7:53 PM, "David davidwhess@... [TekScopes]" <TekScopes@...> wrote:
? On Sat, 26 Mar 2016 12:54:44 -0600, you wrote: ...The DER-EE DE-5000 would be my first choice and recommendation although I do not know how it performs for in-circuit tests. The idea of using ESR to test capacitors strikes me as poor compared to using D (dissipation). ESR is roughly inversely proportional to capacitance while D is constant so it is easier to spot a bad or at least marginal capacitor using D than ESR. #yiv3981593294 #yiv3981593294 -- #yiv3981593294ygrp-mkp {border:1px solid #d8d8d8;font-family:Arial;margin:10px 0;padding:0 10px;}#yiv3981593294 #yiv3981593294ygrp-mkp hr {border:1px solid #d8d8d8;}#yiv3981593294 #yiv3981593294ygrp-mkp #yiv3981593294hd {color:#628c2a;font-size:85%;font-weight:700;line-height:122%;margin:10px 0;}#yiv3981593294 #yiv3981593294ygrp-mkp #yiv3981593294ads {margin-bottom:10px;}#yiv3981593294 #yiv3981593294ygrp-mkp .yiv3981593294ad {padding:0 0;}#yiv3981593294 #yiv3981593294ygrp-mkp .yiv3981593294ad p {margin:0;}#yiv3981593294 #yiv3981593294ygrp-mkp .yiv3981593294ad a {color:#0000ff;text-decoration:none;}#yiv3981593294 #yiv3981593294ygrp-sponsor #yiv3981593294ygrp-lc {font-family:Arial;}#yiv3981593294 #yiv3981593294ygrp-sponsor #yiv3981593294ygrp-lc #yiv3981593294hd {margin:10px 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