On 16.07.14 08:46, Gene Heskett wrote: > On Wednesday 16 July 2014 06:16:36 Erik Christiansen did opine > > 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 > > This one I would modify, with about a 4/1 stepdown toroid in the circuit > where is says 250mv p-p, then use a micropower video speed op amp in place > of the power hungry transistor, set for a gain of about 50.
I like your thinking, Gene. That'd drop the output impedance by a factor of 16 in the bargain, extending its usefulness at the low end. > The stepdown tranny would also, by raising the load impedance on the > paralleled buffer chip, the 74HC14, reduce its power draw, further > extending its battery life. > > With those mods, I like this one better than the one below. A lot better. ... > > Here's one with better low ESR measurement potential: > > > > http://www.ludens.cl/Electron/esr/esr.html > > Looks good, but at 200mv output, it will tickle the socks off todays > digital circuitry. The cap wizard still wins, at 85mv and 100khz. Ah, well, while we're in a modifying mood, we could more than halve the turns on T1's secondary. I'll admit that 100 mV will begin to turn on a low voltage Schottky diode, but it would have to be straight across the capacitor. If there are a couple of junctions in series, e.g. going to ground, then back up somewhere, then we'd mostly get by with 100 mV. But I agree, 200mv is pushing our luck for in-circuit measurement. I'll have to see if I can find the round tuit for building one. There's a spare 200 uA meter movement two feet from my keyboard, a soldering iron at half that distance, and a junkbox which would sink a battleship spread almost everywhere else. Erik -- GALAHAD: No. Look, I can tackle this lot single-handed! GIRLS: Yes, yes, let him Tackle us single-handed! "Monty Python and the Holy Grail" PYTHON (MONTY) PICTURES LTD ------------------------------------------------------------------------------ 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
