Thanks to all for the ESR meter advice.

I had settled on building this *free* ESR meter schemat ...

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


however something troubled me about the schematic

Almost everyone alluded to ESR meters using some
pulse/wave/function passing through CAP to determine the ESR.

and this plan does not appear to have a pulse/wave/function being
fed through the test CAP or am i missing something ?

so is this ESR meter really an ok->good ESR plan ?

If it is not obvious i am looking for cheap (free) ESR
schematic/plans to build

thanks for any helpful replies,
robb

"robb" <some@where.on.net> wrote in message
news:13mvtsa67vgo8c8@corp.supernews.com...
> Thanks to all for the ESR meter advice.
>
> I had settled on building this *free* ESR meter schemat ...
>
> http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
>
>
> however something troubled me about the schematic
>
> Almost everyone alluded to ESR meters using some
> pulse/wave/function passing through CAP to determine the ESR.
>
> and this plan does not appear to have a pulse/wave/function being
> fed through the test CAP or am i missing something ?
>
> so is this ESR meter really an ok->good ESR plan ?
>
> If it is not obvious i am looking for cheap (free) ESR
> schematic/plans to build
>
> thanks for any helpful replies,
> robb
>
>

IC1-B is a "square wave" oscillator. Since there are no values on the drawing,
no way to determine the intended frequency and duty cycle of the oscillator.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

"In theory, there isn't any difference between theory and practice. In
practice, there is." - Yogi Berra

"DaveM" <masondg4499@comcast99.net> wrote in message
news:R9CdnfcFtaxPYPLanZ2dnUVZ_jCdnZ2d@comcast.com...
> "robb" <some@where.on.net> wrote in message
> news:13mvtsa67vgo8c8@corp.supernews.com...
> > I had settled on building this *free* ESR meter schemat ...
> >
> > http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
> >
> > however something troubled me about the schematic
> >
> > Almost everyone alluded to ESR meters using some
> > pulse/wave/function passing through CAP to determine the ESR.
> >
> > and this plan does not appear to have a pulse/wave/function
being
> > fed through the test CAP or am i missing something ?
> >
>
> IC1-B is a "square wave" oscillator. Since there are no values
on the drawing,
> no way to determine the intended frequency and duty cycle of
the oscillator.
>
Thanks DaveM,

Ah ..... of course the omnipotent (well versatile, as i am
learning) opamp.
I knew i must be missing something as someone said this schemat
is not too bad.

i only made it about three pages into the datasheet originally
but when i read your reply i went to page 19 there was an exmple
of using as an oscillator.

thanks Dave for the help,
robb

robb wrote:
> Thanks to all for the ESR meter advice.
>
> I had settled on building this *free* ESR meter schemat ...
>
> http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
>
>
> however something troubled me about the schematic
>
> Almost everyone alluded to ESR meters using some
> pulse/wave/function passing through CAP to determine the ESR.
>
> and this plan does not appear to have a pulse/wave/function being
> fed through the test CAP or am i missing something ?
>
> so is this ESR meter really an ok->good ESR plan ?
>
> If it is not obvious i am looking for cheap (free) ESR
> schematic/plans to build
>
> thanks for any helpful replies,
> robb
>
>

IC1-B is a square wave generator due to the hysteresis design with the
feed back to the (+) input. C3 makes up for the timing frequency used.

The circuit is using the raising edge of the square wave as the time
domain for acquiring readings. Initial raise will only be seen in the
IC1-D circuit due to the small size of C4. R7 will discharge it quickly.

In the bridge it self, if the Test cap has some (R) in it, R9,R9 will
not be at abs 0 volts. The offset is quickly reproduced and amplified
via the IC1-C. Because this is the starting of the square wave from the
generator, C4 will see a sharp raise in the signal and thus C4 being
small like it is, will produce a nice short pulse of the amplitude that
translates to an ohm reading via the IC1-D. After this initial starting
pulse, there will be a continuous reference as a ramp how ever, this will
have little effect.
A perfect cap with 0 ESR, should never allow the sharp raise of the
generate be seen at C4. All you should get is a 0 to 4.5 volt ramp at
best.
But in a cap that has some ESR, the starting ramp will not be at
0(R9+R10) and
this is where the IC1-C will amplify it greatly at the same time the
initial raising of the square wave. DS3 anc C6 will simply hold a
reference for you, between cycles.

I know that is long winded but I think at times it's needed.

--
"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 wrote:
> Thanks to all for the ESR meter advice.
>
> I had settled on building this *free* ESR meter schemat ...
>
> http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
>
>
> however something troubled me about the schematic
>
> Almost everyone alluded to ESR meters using some
> pulse/wave/function passing through CAP to determine the ESR.
>
> and this plan does not appear to have a pulse/wave/function being
> fed through the test CAP or am i missing something ?
>
> so is this ESR meter really an ok->good ESR plan ?
>
> If it is not obvious i am looking for cheap (free) ESR
> schematic/plans to build
>
> thanks for any helpful replies,
> robb
>
>

Assuming I did the math right, IC1-b is producing ~ 95 kHz
into the bridge via TR1 & 2, which is about what is claimed
(100kHz) in the write up.

You can go here to see how the op-amp is configured
and the frequency computed:
http://hyperphysics.phy-astr.gsu.edu/hb ... re.html#c1

The circuit works well, and is real easy on the wallet.

Ed

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:fBVbj.907$si6.581@trndny08...
> robb wrote:
> > Thanks to all for the ESR meter advice.
> >
> > I had settled on building this *free* ESR meter schemat ...
> >
> > http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
> >
> >
> > however something troubled me about the schematic
> >
> > Almost everyone alluded to ESR meters using some
> > pulse/wave/function passing through CAP to determine the ESR.
> >
> > and this plan does not appear to have a pulse/wave/function
being
> > fed through the test CAP or am i missing something ?
> >
> > so is this ESR meter really an ok->good ESR plan ?
> >
> > If it is not obvious i am looking for cheap (free) ESR
> > schematic/plans to build
> >
> > thanks for any helpful replies,
> > robb
> >
> >
>
> Assuming I did the math right, IC1-b is producing ~ 95 kHz
> into the bridge via TR1 & 2, which is about what is claimed
> (100kHz) in the write up.
>
> You can go here to see how the op-amp is configured
> and the frequency computed:
>
http://hyperphysics.phy-astr.gsu.edu/hb ... re.html#c1
>
> The circuit works well, and is real easy on the wallet.
>
> Ed
Tanks Ed,
I am amateur occasional electronics hobbyist trying to learn
more.

i expect this to be quite easy on my wallet as i plan to use all
salvaged components,(because it makes it more interesting for me)
i have found all the components i need on a modem/hard drive
controller /video card boards now for the even more fun part....

thanks for help,
robb

"robb" <some@where.on.net> wrote in message
news:13mvtsa67vgo8c8@corp.supernews.com...
> Thanks to all for the ESR meter advice.
>
> I had settled on building this *free* ESR meter schemat ...
>
> http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
>
>
> however something troubled me about the schematic
>
> Almost everyone alluded to ESR meters using some
> pulse/wave/function passing through CAP to determine the ESR.
>
> and this plan does not appear to have a pulse/wave/function being
> fed through the test CAP or am i missing something ?
>
> so is this ESR meter really an ok->good ESR plan ?
>
> If it is not obvious i am looking for cheap (free) ESR
> schematic/plans to build
>
> thanks for any helpful replies,
> robb


Hi, Robb -

I used SPICE to simulate the important parts of the circuit composed of the
bridge and IC1-C and IC1-D. I used a pulse generator rather than IC1-B. I
used voltage-controlled-voltage-sources rather than op-amp models. I looked
up an arbitrary capacitor's ESR for this simulation.

I got the following output "indications" vs capacitor (arbitrarily 100uF)
ESR:

ESR (ohms) Indication (percent)
0 100
..018 100 (specified value)
..18 99
1.8 92
18 52
180 7

A 10uF with 0 ESR also indicated 100%.

So, the circuit appears to work, but it depends on what you are expecting
from it as to how well it works. If you decide that anything below, say, 50%
is bad, you may not catch the capacitor that causes equipment to fail when
it has more than 1.8 to 18 ohms of ESR.

I think the amount of ESR that can be tolerated will depend on the target
equipment's sensitivity to ESR. In some cases, you may find that even 1.8
ohms causes malfunction. In other cases you may find that 1K ohms of ESR
causes no problems.

To verify the simulation, you could build the meter and test various
capacitors known to be new and good. Then add some series resistance to each
and record the readings. Then all you would need is experience to know when
equipment will fail due to high ESR.

Cheers,
John

"John" <see@my.sig> wrote in message
news:H2tcj.3474$nh7.2098@trnddc01...
> "robb" <some@where.on.net> wrote in message
> news:13mvtsa67vgo8c8@corp.supernews.com...
> > Thanks to all for the ESR meter advice.
> >
> > I had settled on building this *free* ESR meter schemat ...
> >
> > http://www.qsl.net/iz7ath/web/02_brew/15_lab/06_esr/
[trim]
>
> Hi, Robb -
>
> I used SPICE to simulate the important parts of the circuit
composed of the
> bridge and IC1-C and IC1-D. I used a pulse generator rather
than IC1-B. I
> used voltage-controlled-voltage-sources rather than op-amp
models. I looked
> up an arbitrary capacitor's ESR for this simulation.
>
> I got the following output "indications" vs capacitor
(arbitrarily 100uF)
> ESR:
>
> ESR (ohms) Indication (percent)
> 0 100
> .018 100 (specified value)
> .18 99
> 1.8 92
> 18 52
> 180 7
>
> A 10uF with 0 ESR also indicated 100%.
>
> So, the circuit appears to work, but it depends on what you are
expecting
> from it as to how well it works. If you decide that anything
below, say, 50%
> is bad, you may not catch the capacitor that causes equipment
to fail when
> it has more than 1.8 to 18 ohms of ESR.
>
> I think the amount of ESR that can be tolerated will depend on
the target
> equipment's sensitivity to ESR. In some cases, you may find
that even 1.8
> ohms causes malfunction. In other cases you may find that 1K
ohms of ESR
> causes no problems.
>
> To verify the simulation, you could build the meter and test
various
> capacitors known to be new and good. Then add some series
resistance to each
> and record the readings. Then all you would need is experience
to know when
> equipment will fail due to high ESR.
>
> Cheers,
> John

Thanks for the info, help and effort John,

I would try something like a simulation if i did not already have
a hobby workbench overflowing with projects/ideas etc...

This ESR project fell out of another (in-complete) vintage
microcontroller project i was working on. That was put on hold
because the ever important ROM was fried and i am trying to
locate a source for a ROM image and in the meanwhile trying to
see if a could not engineer a new 8051 application to replace the
original ROM program.

hobbying really does eat up alot of time,
thanks again for your help and reply,
robb