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From: Martin Griffith on 21 Dec 2007 16:57
On Fri, 21 Dec 2007 16:43:07 -0500, in sci.electronics.design "robb"
<some(a)where.on.net> wrote:

>
>"Martin Griffith" <mart_in_medina(a)ya___.es> wrote in message
>news:jqbom35psbel5fh6dko4no0ogkhg0riicu(a)4ax.com...
>> On Fri, 21 Dec 2007 16:19:08 -0500, in sci.electronics.design
>"robb"
>> <some(a)where.on.net> wrote:
>> > after diagnosing an old microcontroler board with lots of
>various
>> > old caps i thought maybe an ESR meter to be a good tool for
>the
>> > tool box ? yes/no or a better tool for the box
>> >
>> > so i googled for some ESR meter plans and settled on this one
>> >
>> > http://ludens.cl/Electron/esr/esr.html
>> >
>> >could someone comment on this design and whether it appears to
>be
>> >good/bad ?
>> >
>> If it's a really old piece of kit , and has electro caps in it,
>just
>> replace the lot.
>> They guys who built it probably didn't know what ESR was in
>those
>> days, it's only become obvious with modern smps IC's, needing
>miniohms
>> of ESR
>>
>hello martin,
>thanks for reply.
>i understand your point and i will likely do that
>however the trouble as pointed out on that ESR schematic website
>is that even brand new caps can have numerous ESR failures. So i
>was thinking before i invest all that time changing out all those
>caps i should at least test the new caps for ESR failures ?
>
>thanks for the advice,
>robb
>
Couldn't cope with the graphics on the web site, but in the old days,
you would just stick 10uF here, 10uF there, and a splattering of a
100nF everywhere, ESR wasn't even in the equation in those days.

And I don't think that a site selling ESR meters would say that
Quality Control in modern factories is quite good.... a bit of FUD
maybe


martin
From: Chuck Olson on 21 Dec 2007 18:56

"robb" <some(a)where.on.net> wrote in message
news:13moba473pnjobb(a)corp.supernews.com...
> after diagnosing an old microcontroler board with lots of various
> old caps i thought maybe an ESR meter to be a good tool for the
> tool box ? yes/no or a better tool for the box
>
> so i googled for some ESR meter plans and settled on this one
> ....
>
> http://ludens.cl/Electron/esr/esr.html
>
> could someone comment on this design and whether it appears to be
> good/bad ?
> are there better plans to build ? are there any improvement mods
> that should could be made ?
>
> thanks for any help,
> robb
>
>
I built this one http://www.flippers.com/esrktmtr.html - - really good - -
have enjoyed using it for about 4 months, now. Check out my comment on the
flippers website about 3/4 of the way down the page.

Chuck Olson W6PKP


From: Jamie on 21 Dec 2007 18:06
robb wrote:

> after diagnosing an old microcontroler board with lots of various
> old caps i thought maybe an ESR meter to be a good tool for the
> tool box ? yes/no or a better tool for the box
>
> so i googled for some ESR meter plans and settled on this one
> ....
>
> http://ludens.cl/Electron/esr/esr.html
>
> could someone comment on this design and whether it appears to be
> good/bad ?
> are there better plans to build ? are there any improvement mods
> that should could be made ?
>
> thanks for any help,
> robb
>
>
My opinion, It does not come close to actually giving you a true
ESR reading.
All the design is doing is relying on high valued capacitors assumed
to still have life and hoping to display the effective series resistance
in them by assuming the Xc to be at a very low value with the 50khz
referenced used.
In practice, that isn't a real ESR meter.

When I worked at Semco, the preferred method used on the automation line
for ESR testing was to apply a 1 us pulse to the cap via a low value
R from a stable pulse source.
Both the pulse source and net result reference from the cap under
going a test were being monitored via a high speed comparator.
When the pulse source reached it's max peak it would force another
comparator to briefly update a sample and hold circuit for a generate
voltage offset difference;

Theory of operation was that most caps when discharged (shunt shorted)
would exhibit virtual 0 (Xc)with a fast raise pulse, and the net results
of the resistance formed by construction and leads would then not allow
for an absolute short to common which would give you a reference to work
with that could then be translated into Ohms.
Part of the components were mounted in the probe assembly arm to
reduce induction in the equation.

Using this method, it did not matter if the cap was a small or large
value type. it simply only did the acquisition of readings on a single
positive transition.

This method was check against other equipment in the lab that was
designed for Q testing of small and medium value and found to be very
accurate.


--
"I'd rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:

SOME PEOPLE ARE LIKE SLINKIES. NOT REALLY GOOD FOR ANYTHING BUT
THEY BRING A SMILE TO YOUR FACE WHEN PUSHED DOWN THE STAIRS.
http://webpages.charter.net/jamie_5"

From: D from BC on 21 Dec 2007 18:21
On Fri, 21 Dec 2007 15:56:36 -0800, "Chuck Olson"
<chuckolson01(a)REMOVETHIScomcast.net> wrote:

>
>"robb" <some(a)where.on.net> wrote in message
>news:13moba473pnjobb(a)corp.supernews.com...
>> after diagnosing an old microcontroler board with lots of various
>> old caps i thought maybe an ESR meter to be a good tool for the
>> tool box ? yes/no or a better tool for the box
>>
>> so i googled for some ESR meter plans and settled on this one
>> ....
>>
>> http://ludens.cl/Electron/esr/esr.html
>>
>> could someone comment on this design and whether it appears to be
>> good/bad ?
>> are there better plans to build ? are there any improvement mods
>> that should could be made ?
>>
>> thanks for any help,
>> robb
>>
>>
>I built this one http://www.flippers.com/esrktmtr.html - - really good - -
>have enjoyed using it for about 4 months, now. Check out my comment on the
>flippers website about 3/4 of the way down the page.
>
>Chuck Olson W6PKP
>

The kit is from Vancouver BC
We make some stuff out here.. :)


D from BC
From: me on 21 Dec 2007 18:19
"robb" <some(a)where.on.net> wrote in
news:13moba473pnjobb(a)corp.supernews.com:

>after diagnosing an old microcontroler board with lots of various
>old caps i thought maybe an ESR meter to be a good tool for the
>tool box ? yes/no or a better tool for the box
>
>so i googled for some ESR meter plans and settled on this one
>....
>
> http://ludens.cl/Electron/esr/esr.html
>
>could someone comment on this design and whether it appears to be
>good/bad ?
>are there better plans to build ? are there any improvement mods
>that should could be made ?
>
>thanks for any help,
>robb
>
>

I built and use it. It is adequate for good/bad/questionable diagnosis.
It is also simple to assemble, I built mine from "junk" parts. I don't
think I could beat it for the price...
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