ESR Meter confusion

One of my digital multimeters has a capacitor test built into it. But I dont believe that tests the ESR. I've recently read many articles and watched videos about testing the ESR of caps. I wanted to buy an inexpensive ESR tester and went to ebay. I am just a hobbyist on a low fixed income so I cant pay a lot.

Anyhow, that is where I got real confused. Several say ESR, while others are just cap testers. Looking at the pictures on the ebay pages, they all look alike. So, whaT is really different between them? I sure cant tell. Links to low cost models on ebay that would suit my needs appreciated. (I DO NOT use Amazon).

Reply to
maysdairy
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I just picked one cheap and cheap or no shipping from China. There may be program differences. Non of them measure high values of capacitance. Mine is the component testor. Most devices included in testing.

Greg

Reply to
gregz

You can't beat free.

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Works for 30 days before some features get disabled, but looks like the ESR may still work after that. I played with an earlier version years ago and found it very useful for ESR testing.

It uses a PC sound card for testing.

It requires a stereo microphone input. Some computers have mono microphone input and won't work. I had a soundblaster USB at the time.

There's discussion of sound cards on their site.

Might be worth a look. YMMV.

Reply to
Mike

There are many of those "$5 including shipping" component testers on ebay and aliexpress that you can try, they automatically determine the component you plug in the ZIF socket and when it is a capacitor they also indicate the ESR. This is a nice toy for the low-budget hobbyist.

Reply to
Rob

Do you have a 'scope and function generator? How much accuracy do you need/ want?

George H.

Reply to
George Herold

those things are quite handy. They test a lot more than caps of course. Plenty of limitations but a good choice for the hobbyist, and quite useful for the non-hobbeast.

NT

Reply to
tabbypurr

If he has a scope, he doesn't need an ESR tester; just scope the ripple.

One old TV repair trick was to in-circuit parallel a suspect cap with a good one. If that fixed the set, leave them both in.

ESR testers are a sort of amateur cult thing. Most cheap and many not cheap L/C and ESR meters are awful.

Fun: measure an inductor with several different L meters.

--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

They're good enough to tell a good cap from a dud. I've found that useful. It may be worth bearing in mind I've worked on kit from every decade back to the 1920s.

If you want inductors tested over a range of currents you'll need more than a basic tester. Coils of wire are more complex than they appear.

NT

Reply to
tabbypurr

Ah, well, no, never a good idea as the old cap was likely leaky and as such slowly turning into a resistor... Ever felt the cans on those old electros? If the can was warm/hot then the cap was assumed bad. Warmer than the chassis that is.

Bob Parkers ESR kit is still outstanding - I've lost count how many we sold after the 1,000 mark passed 15 years ago. We still sell a dozen or so a year. And continue to use one in our own service shop.

John :-#)#

Reply to
John Robertson

I was going to tell him your trick of voltage step into a cap and reading ESR off the step part of the response. That works for certain values.

I'm not sure I always trust our expensive LCR meter. There's this old Boonton radio Q-meter on the equipment shelves... It worked last time I turned it on. (Good for HF stuff)

George H.

Reply to
George Herold

If you have a square wave generator and a scope, that test is a lot more believable than a number on some ESR meter. It suggests ESL too.

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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

Right. I think when I tried it I used the edge from my function generator and that's not as fast as it could be.

George h.

Reply to
George Herold

I used my old B+K analog function generator for that pic. It doesn't need to be super fast. The scope sweep was 4 us/cm.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

w2aew has a very good explanation of measuring ESR with a scope and function generator.

Cheers

Reply to
Martin Riddle

Not very good. For the "bad" cap, he's not properly separating the ESR from the capacitance.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

Heathkit made a nice LC tester that used a Magic Eye tube to show results. One feature of this meter was a Power Factor and that was handy for seeing how well electrolytic caps performed under load. I don't bother any more because most modern caps with a good name brand are much better than the oldies so we usually just replace electros (and the rest) in tube equipment then troubleshoot.

John :-#)#

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(Please post followups or tech inquiries to the USENET newsgroup) 
                      John's Jukes Ltd. 
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Reply to
John Robertson

Yup - but in fairness he does explain how to. And if you're just looking for bad caps, it doesn't matter which caused the problem, ESR or loss of C.

NT

Reply to
tabbypurr

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The question is whether the meters are awful or if the parallel and serial resistances are a little too distributed to be usefully characterised by a measurement at a single frequency.

Inductors have series resistance in the windings, and a parallel resistance due to the current inducted in the core material (if they have a core, whi ch most do). The series resistance in the windings eventually increases wit h frequency because of the skin effect.

All great fun to do properly, but who has the time, or the multi-frequency impedance bridge ...

--
Bill Sloman, Sydney
Reply to
bill.sloman

OK, I'll have to try it again sometime. I think I used my Rigol FG.. may not be as snappy as the wavetek.

George H.

Reply to
George Herold

Hmm... it's not that bad. You should be able to get R and C for the bad one.

GH

Reply to
George Herold

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