BC107 Posted January 11, 2012 Report Share Posted January 11, 2012 Hi I'v just finished an ESR meter based on Ludens simple analog circuit, which seems to work very well. I did a small mod to broaden the range a bit, so 4.7 ohm is below mid scale great. Works fine.Here's the Puzzle!.I short the test leads out to zero the meter fine.Then If I measure a 'NON Polarized' 1.5uf polycarb capacitor it takes the meter about 5mm Past the zero point!, It also goes over the zero on another 2.2uf non polar cap I have?How can this be?. If a short circuit limits the meter to Zero FSD. how can measuring a non Polar cap send it further over the Zero?As for electrolytics the meter works fine.Any Info would be much appreciated.Thanks all Quote Link to comment Share on other sites More sharing options...
Hero999 Posted January 12, 2012 Report Share Posted January 12, 2012 How are we supposed to know? Quote Link to comment Share on other sites More sharing options...
BC107 Posted January 13, 2012 Author Report Share Posted January 13, 2012 How are we supposed to know?Well i'm aiming my question at electronic engineers with some 'mature' experience to reply, sorry if I missed the mark.! (with you) Quote Link to comment Share on other sites More sharing options...
Hero999 Posted January 13, 2012 Report Share Posted January 13, 2012 Well i'm aiming my question at electronic engineers with some 'mature' experience to reply, sorry if I missed the mark.! (with you)Yes you did miss the mark by not providing enough information: schematic, PCB layout, pictures etc. - we're electronic engineers not mind readers. Quote Link to comment Share on other sites More sharing options...
BC107 Posted January 14, 2012 Author Report Share Posted January 14, 2012 Hi Hero999, yes I see your point I assumed only people interested in ers meters would answer, where Ludens circuit would be well known. Anyway I though "How are we supposed to know?" was a bit cryptic, where it could have been "How are we supposed to know? unless you show us the circuit!"..!Anyway I get your point, I'll be more detailed in future postsCheers Quote Link to comment Share on other sites More sharing options...
BC107 Posted January 14, 2012 Author Report Share Posted January 14, 2012 Problem Sorted..!!!It seems the over reading was caused by the leakage inductance of the transformer, where the capacitor partially resonates with the inductive component to give a greater current than the short circuit.Many thanks to 'Jimmc' from EEVblog for this insite.This has now been turned to my advantage by including the best value NON polar polycarb cap in series with the capacitor under test as a permenent mod to my meter.Many thanks to all for your comments,Cheers Quote Link to comment Share on other sites More sharing options...
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