From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 2020-05-28 15:54, Ralph Mowery wrote:   
   >   
   >   
   > Today I received one of the roughly  $ 20 component testers.  Checking   
   > it out and comparing capacitors I notices a big difference in a couple   
   > of them   
   >   
   > I was using a Fluke 87,  a LCR meter from China, an older component   
   > tester and the new component tester.   
   >   
   > The first capacitor was a Sprague .06 uF 600V.  Two China testers showed   
   > near the value.  Within the 10%  tollorence,    The LCR tester showed it   
   > to be .08 and the Fluke as .1 uF.   
   > This is a new,but very old capacitor.   
   >   
   > Next capacitor was a 20 year old no name of .068 of 50 V made with the   
   > Poly something dielectric.  All meters were with in less than 10 %.  Ok   
   > here.   
   > Same results with a newer one of .01 uF .   
   >   
   > Next came a Silver mica.  It is .01 at 600 V. Fluke shows up at .0150,   
   > LCR at  .0120.  Two component testers were close and in spec.   
   >   
   >   
   > What gives with some capacitors checking like they should and some being   
   > way off, not just 10 % or so ?  I ran the tests several times on each   
   > capacitor to see if maybe the leads were not making good contact and any   
   > other similar thing I may have missed like having my fingers across the   
   > leads.   
   >   
   > Ralph ku4pt   
   >   
      
   Might be bad soakage--micas are horrible for that.  If you stick a 1-Hz   
   square wave into it and look at the voltage across a the 1-M input   
   impedance of your scope, you might see something interesting.   
      
   Scoping what the meters are doing to the cap would be interesting too.   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
   http://electrooptical.net   
   http://hobbs-eo.com   
      
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