advise on ESR meter project ?

[robb]

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

 

[Martin Griffith]

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

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


martin

 

[AJ]

Bob Parker ESR Meter kits are available ad a reasonable price. Google for
them.

 

[David L. Jones]

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

Don't bother with that one, get what everyone else in the industry
has:
http://members.ozemail.com.au/~bobpar/esrmeter.htm

Bob Parker hangs out on the aus.electronics group, so you can ask
questions there.

There is also this one, which even Bob himself has heard good reports
about:
http://www.peakelec.co.uk/acatalog/jz_esr60.html

Dave.

 

[robb]

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

 

[Martin Griffith]

Bob Parker ESR Meter kits are available ad a reasonable price. Google for
them.

OK, nothing wrong with having an ESR meter, but repairing old bits of
kit, say over 10 years old, just recap the lot, no need for a meter,
and the caps today are a lot better than the 80's.

Are you really going to remove a 20 year old cap, measure it and then
say " that's shit, that one is shit as well, so's that one", then
stuff the occasional good one back into the pcb...., just replace them
all



martin

 

[Martin Griffith]

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

 

[Jamie]

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"

 

[me]

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...

 

[D from BC]

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

 

[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.

so this luden's ESR gives no useful info about a cap ? and its
a waste of time design ?

Thanks for advice Jamie,
robb

 

[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

Thanks for reply chuck,
That looks alot like those Bob Barker ESR meters

Thanks for help,
robb

 

[Chuck Olson]

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

 

[Jamie]

so this luden's ESR gives no useful info about a cap ? and its
a waste of time design ?

Thanks for advice Jamie,
robb

from what I can see, it's not fully implemented to give you an
accurate reading. If you were to have a failed cap due to loss
of capacitance, it will give you the conclusion that it has a
high ESR but that isn't true how ever.
A circuit like that could work much better if it was modified.
the idea of pumping in a square wave of 50khz into that xformer
most likely generates +/- pulses if the induction is low enough.

My self, I would of used a bridge type sensing circuit from the
source and from the cap test point with a low (R) between the source
and test cap to measure the offset on the transition period.
With this type of config, the cap would be in as a shunt and not as
a series component.
all one would need to do is cross the leads for 0 calibration before
test begins.

If you don't know enough to mod this unit, maybe you should look for a
simple LCR meter with that function on it.?

I haven't really seen to much on the net for a stand alone ESR meter.
I think most just get a unit that does LCR/ESR.
something like the below link. THat's a bench model how ever, they make
a hand held also.

http://rocky.digikey.com/WebLib/B & K Precision/Web Photo/889.jpg

--
"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"

 

[robb]

in message news:[email protected]...

[ trimmed ] ...
Jamie says .....
My self, I would of used a bridge type sensing circuit from the
source and from the cap test point with a low (R) between the source
and test cap to measure the offset on the transition period.
With this type of config, the cap would be in as a shunt and not as
a series component.
all one would need to do is cross the leads for 0 calibration before
test begins.

Hi jamie speaking of using a bridge circuit how does this design
look ?

http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/

If it is not obvious i am looking for cheap (free) ESR
schematic/plans to build
thanks for the help ,
robb

 

[Jamie]

robb wrote:


wrote

one

[ trimmed ] ...

Jamie says .....
My self, I would of used a bridge type sensing circuit from
the

source and from the cap test point with a low (R) between the
source

and test cap to measure the offset on the transition period.
With this type of config, the cap would be in as a shunt and

not as

a series component.
all one would need to do is cross the leads for 0

calibration before

test begins.

Hi jamie speaking of using a bridge circuit how does this design
look ?

http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/

If it is not obvious i am looking for cheap (free) ESR
schematic/plans to build
thanks for the help ,
robb

now you're cooking with GAS!

yes, That one will do just fine!


--
"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"

 

[ehsjr]

robb wrote:


wrote

one

[ trimmed ] ...

Jamie says .....
My self, I would of used a bridge type sensing circuit from
the

source and from the cap test point with a low (R) between the
source

and test cap to measure the offset on the transition period.
With this type of config, the cap would be in as a shunt and

not as

a series component.
all one would need to do is cross the leads for 0

calibration before

test begins.

Hi jamie speaking of using a bridge circuit how does this design
look ?

http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/

If it is not obvious i am looking for cheap (free) ESR
schematic/plans to build
thanks for the help ,
robb

I built that one, the cost is low, and it works fine
for what you want to do. If you want a laboratory
grade instrument, look elsewhere.

Ed

 

[Jan Panteltje]

so this luden's ESR gives no useful info about a cap ? and its
a waste of time design ?

Thanks for advice Jamie,
robb

I have no ESR meter, but many times if I wanted to know about caps
I just used 2 scope channels, substract, and in that way monitor
the voltage over the cap, and IF it shows fast transients the cap
is defective.
This method works nice in switchmodes.
And indeed the applying a pulse method is likely the best, and can be used
in the same way.
I hope you have an analog scope

 

[Paul Mathews]

in message

robb wrote: one

[ trimmed ] ...

Jamie says .....
   My self, I would of used a bridge type sensing circuit from the
  source and from the cap test point with a low (R) between the source
   and test cap to measure the offset on the transition period.
   With this type of config, the cap would be in as a shunt and not as
   a series component.
   all one would need to do is cross the leads for 0 calibration before
test begins.

Hi jamie speaking of using a bridge circuit how does this design
look ?

http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/

If it is not obvious i am looking for cheap (free)  ESR
schematic/plans to build
thanks for the help ,
robb- Hide quoted text -

- Show quoted text -

For quick go/nogo indication, those simple ESR meters are handy and
useful. If you happen to have access to some simple equipment, you can
measure ESR and Self Resonant Frequency as follows:
Connect a signal generator output to the capacitor under test. Connect
the trigger output of the generator to scope trigger input. Connect 1
scope channel across cap under test. If a current probe is available,
monitor cap current with it. Otherwise, connect a low value resistor
in series with the ground lead of the cap under test and use a 2nd
scope channel to monitor the voltage across this sense resistor. With
the signal generator set at a low frequency (where Xc is high compared
to the sig gen's output Z), increase sig gen output and scope chan
sensitivities for clean waveforms. Increase frequency and observe
decreasing voltage across cap and increasing current through cap,
along with changing phase relationship. Readjust scope controls as
necessary. Eventually, you will reach a frequency where voltage and
current are in phase, and further increases in frequency cause
decreases in current. The ratio of voltage to current at this
frequency is a good estimate of ESR, and the frequency is near the
SRF. This procedure can be time consuming, but, if you have already
have scope and sig gen, you'll learn a lot about each cap you test.
Paul Mathews

 

[Jean-Yves]

so this luden's ESR gives no useful info about a cap ? and its
a waste of time design ?

Thanks for advice Jamie,
robb

[/QUOTE]

I bought recently this one :

http://www.m3electronix.com/lcr.html
(the french version but it works the same)

nice kit, and with the esr meter you have for the same price of most of
esr meters kits , a precise LCR meter !!!
this is a valuable instrument I really enjoy mine !

regards.