On 16.07.14 04:27, Gene Heskett wrote: > The only test tool I ever found that does a decent job of measuring this > is called a "Capacitor Wizard", and sells for about 180-200 dollars on > this side of the pond. Google for it.
If the usage is there, it may well be worth the price, although a useful but basic instrument can readily be put together. The circuits which are thrown up by a "ESR meter circuit" google vary noticeably in complexity, but are mostly pretty cheap to build. Since it only takes a 0.1 ohm and 1 ohm resistor or similar from the junkbox to calibrate them, some of them pretty much have to be good enough for identifying dud electrolytics, and even those which are marginal. I've only glanced through this article, but it doesn't look too bad, and provides a good background for anyone needing an ESR primer: http://kakopa.com/ESR_meter/ But it admits to being a bit insensitive at the low end. This one talks about 1 ohm being 90% of full scale. That would just about do me until I found perfection: http://members.shaw.ca/swstuff/esrmeter.html There are also circuits with transformers between oscillator and the test capacitor, to lower the source impedance. That would be needed for low ESR caps, I think. I'm tempted to add a cap and a step-down transformer to an existing design which is otherwise appealing. I bought a slab of Siemens RM4 ferrite core and bobbin sets for a song the other day. Now I have a use for one of them. Here's one with better low ESR measurement potential: http://www.ludens.cl/Electron/esr/esr.html Who's found a better one? The thing is to know whether the circuit needs Low ESR caps, or ordinary ones will do. If they are in a SMPS, or the power section of a VFD, then bank on it. Erik -- If the theological answer to all questions had ever actually prevailed in the world the progress of the race would have come to an end, and there would be no difference today between a good European and a good pygmy in the African jungles. Everything that we are we owe to Satan and his bootleg apples. - H.L. Mencken ------------------------------------------------------------------------------ Want fast and easy access to all the code in your enterprise? Index and search up to 200,000 lines of code with a free copy of Black Duck Code Sight - the same software that powers the world's largest code search on Ohloh, the Black Duck Open Hub! Try it now. http://p.sf.net/sfu/bds _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
