Where are all the ESR meters?

[ehsjr]

So, you want to flash the silver off the contacts to metalize the
insides of the switch's body, or even weld them together?

Good point on the switch contact resistance. With
Terry's mod, the arc will be at the probes, not in
the switch. Someone asked about the loud bang when
you connect the probes - I think it should be there.
It adds a "feeture" to the instrument: an audible
indication that when translated from "electronian"
says "Hey asshole! You're probing a charged cap".

Ed

 

[Fred_Bartoli]

ehsjr a écrit :

Good point on the switch contact resistance. With
Terry's mod, the arc will be at the probes, not in
the switch. Someone asked about the loud bang when
you connect the probes - I think it should be there.
It adds a "feeture" to the instrument: an audible
indication that when translated from "electronian"
says "Hey asshole! You're probing a charged cap".

Yup, and make that to a solid tant cap and you've found a good way to
have to change it.

You can also fry some other components in the process, depending on
other caps that were still being charged and on the circuit.

 

[John Devereux]

I posted a schematic to abse. Nobody else did anything but blather
about kelvin clips and dreams of ideal behavior.

I note that you didn't post a design, either.

I can't get that group - and I suspect not many others can either

It looks like you could do a lot with this chip:

<http://www.analog.com/en/prod/0,,762_0_ADUC7128,00.html>

but perhaps that's cheating.

It has a DDS (that could generate the excitation), 1MHz 12 bit ADC and
quite a fast 32 bit CPU.

 

[Michael A. Terrell]

Good point on the switch contact resistance. With
Terry's mod, the arc will be at the probes, not in
the switch. Someone asked about the loud bang when
you connect the probes - I think it should be there.
It adds a "feeture" to the instrument: an audible
indication that when translated from "electronian"
says "Hey asshole! You're probing a charged cap".

Ed

I still have a couple of those surplus Radio Shack 20 second digital
voice recorders. Should it yell, 'You idiot!', or have it 'Bray like
the old donkey on Hee Haw'? Maybe a loud thunder clap, to go with the
artificial lightning? ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

I can't get that group - and I suspect not many others can either

http://www.usenet-replayer.com/ allows you to read binaries
newsgroups.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[John Devereux]

http://www.usenet-replayer.com/ allows you to read binaries
newsgroups.

Thanks - at least I can see what others are talking about.

 

[Fred Bloggs]

**** you...

You can go somewhere else, ....

Then I got in his face ...

That shut the old shit up.

Bite me, jackass.

I'm tired of morons...


Other assholes have tried to run me down in a parking lot, almost
hitting the row of parked cars I was just inches from. They were
looking right at me when they steered the car towards me.
A hispanic moron in a jacked up car with flames painted on the sides
was cursing at me in English, then in Spanish to get the hell out of the
way, because I was walking too slow. I was in a marked crosswalk, in
front of a supermarket.
People constantly intentionally block my path when I'm walking with
the cane. They shove a shopping cart up against the cane and stare at
me.
Quite often someone will se me headed for a cash register and shove
their cart into mine to cut in front of me.
These are not rare instance,...

I am not "Playing victim", ....

 

[Winfield]

If the DUT is a large capacitor charged to several hundred volts, that
would have to be one heck of a switch.

I think it would be far better to make a current source and voltage
preamp that can both withstand several hundred volts.

Neither the current source nor the voltage preamp needs to be super
good they just have to not crosstalk. Assuming we have well regulated
+/- 12V supplies, the current source can be just a rail to rail output
driving a resistor. For a measurement current of 1mA, a 12K resistor
would be required. Assuming we have to withstand 500V, we need a
resistor that can take a 21W pulse.

Operating at 1mA results in about a 1uV measurement requirement. This
would let us use a resistor on the order of 100K on the input of the
preamp without getting swamped with noise.

Your numbers don't compute for me. I'd like a 100mA
signal if it worked out, but have accepted 10mA as a
compromise. 1mA seems very wimpy, but assuming that,
your 12V suppiy (while a pain for batteries) doesn't
allow proper operation if there's very more than 12V
sitting on the cap. And your 12k resistor would mean
a 1-min discharge time constant with say 5000uF, yawn,
waiting to get within the operating-voltage range.

I'm going for 25 ohms of discharge resistance, using
another set of diodes to +/-3V rails. Of course, the
rails must have a way to get rid of any excess energy.

 

[Winfield]

Yup, and make that to a solid tant cap and you've found a good way to
have to change it.

You can also fry some other components in the process, depending on
other caps that were still being charged and on the circuit.

I don't like a switch, because I don't have three hands.

 

[Michael A. Terrell]

Thanks - at least I can see what others are talking about.

You can comment about it here, and post any of your graphics online
with a link here, as a workaround.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

Too drunk to post your usual venom?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

It's not just VA. Medicare doesn't cover dental either. My wife had
over $12K of dental surgery last year due to (what you seem to have) a
tooth infection that got into the jawbone.

She has my sympathy. OTOH, she didn't have to put up with Fred's
attempts to add to her pain.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Spehro Pefhany]

Win, thank you for your concern. They are treating symptoms, not the
real problem. Thanks to Congress the VA is not allowed to treat it.

[snip]

It's not just VA. Medicare doesn't cover dental either. My wife had
over $12K of dental surgery last year due to (what you seem to have) a
tooth infection that got into the jawbone.

...Jim Thompson

Ouch. Our health care plan here doesn't cover dentistry (a lot of
families have Blue Cross or whatever supplemental coverage through
employers) but it does cover dental surgery (non cosmetic) and
pathology type stuff done by specialists. As part of cost-cutting
they've been dropping little things (like annual eye examinations for
people without diabetes/glaucoma etc) but so far nothing major. I
don't mind paying a few hundred now and then for routine things.


Best regards,
Spehro Pefhany

 

[Chris Jones]

A quick look at the schematic and writeup suggests that it can't
untangle ESR from capacitance at low C values. The "good esr versus
capacitance" chart screened on the front confirms.

True but so far I have never come across a situation where this was a
problem for me.

Besides, this is sci.electronics.design, not sci.electronics.copy.

As long as you make something that is really more useful in practice, not
simply motivated by the "Not Invented Here" instinct, then fair enough and
good luck.

Chris

 

[ehsjr]

I still have a couple of those surplus Radio Shack 20 second digital
voice recorders. Should it yell, 'You idiot!', or have it 'Bray like
the old donkey on Hee Haw'? Maybe a loud thunder clap, to go with the
artificial lightning? ;-)

Maybe all of them!

But you know, it's like JL said: it seems whatever idea
gets posted, someone objects to it. Your idea, zany as
it might seem, could actually be good. The meter "talks"
to you when you do the bonehead move. I'm not suggesting
"voice output" for all readings, but an "extended" audible
indication that the cap was charged should get one's
attention. The "bang" might be too brief or not loud enough.

Ed

 

[ehsjr]

ehsjr a écrit :


Yup, and make that to a solid tant cap and you've found a good way to
have to change it.

You can also fry some other components in the process, depending on
other caps that were still being charged and on the circuit.

Good point. So your idea is to add a resistor,
or to abandon the switch or ?

Ed

 

[Michael A. Terrell]

Maybe all of them!

But you know, it's like JL said: it seems whatever idea
gets posted, someone objects to it. Your idea, zany as
it might seem, could actually be good. The meter "talks"
to you when you do the bonehead move. I'm not suggesting
"voice output" for all readings, but an "extended" audible
indication that the cap was charged should get one's
attention. The "bang" might be too brief or not loud enough.

Ed

I had to rewrite some test software (In Qbasic, of all things) for an
automated test fixture. If the board was good, it was done before you
could fill in the job and serial numbers on the test data sheet. (They
let us build and use an automated test fixture, but refused to change
the test data sheet. that meant you still had to check off 25 'passed'
boxes, instead of one.)

As the software evolved, I added troubleshooting instructions, and
finally two sound effects. If it failed, it sounded like a fog horn,
and paused for troubleshooting. If it passed, it sounded like the old
Atari video games, with the rising notes. The boss freaked out, when he
heard it one day. he was yelling, OK! Who is playing games! When he
found out what it was, he just shook his head and walked away.

If it passed, you put in the next board and started the test while
you finished the first data sheet and started the next test data sheet.


The idea I had for a computer interfaced ESR test set had the option
of saying pass or fail, when used for incoming inspection. I don't know
where my notes and software are. There are about 35 used, low capacity
hard drives stuffed into boxes. One might still have my notes and
preliminary circuit. The GUI allowed you to select brand, then series,
voltage and capacitance. That called up the specifications for the
part, and included tolerance for either repair work or go/nogo testing.
In that mode it could be used standalone, after programming it. If I
was doing it today, I would probably add some flash memory to store all
the capacitor data I could, and use a small LCD display for setup and
testing.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Winfield]

I had to rewrite some test software (In Qbasic, of all things) for an
automated test fixture. If the board was good, it was done before you
could fill in the job and serial numbers on the test data sheet. (They
let us build and use an automated test fixture, but refused to change
the test data sheet. that meant you still had to check off 25 'passed'
boxes, instead of one.)

As the software evolved, I added troubleshooting instructions, and
finally two sound effects. If it failed, it sounded like a fog horn,
and paused for troubleshooting. If it passed, it sounded like the old
Atari video games, with the rising notes. The boss freaked out, when he
heard it one day. he was yelling, OK! Who is playing games! When he
found out what it was, he just shook his head and walked away.

If it passed, you put in the next board and started the test while
you finished the first data sheet and started the next test data sheet.

The idea I had for a computer interfaced ESR test set had the option
of saying pass or fail, when used for incoming inspection. I don't know
where my notes and software are. There are about 35 used, low capacity
hard drives stuffed into boxes. One might still have my notes and
preliminary circuit. The GUI allowed you to select brand, then series,
voltage and capacitance. That called up the specifications for the
part, and included tolerance for either repair work or go/nogo testing.
In that mode it could be used standalone, after programming it. If I
was doing it today, I would probably add some flash memory to store all
the capacitor data I could, and use a small LCD display for setup and
testing.

Now, *that* would be an esr meter!

 

[Michael A. Terrell]

Now, *that* would be an esr meter!

It would probably not appeal to a wide market segment, so it was being
designed for personal use. It would be great in a small shop where you
could program it and have someone check a box capacitors before putting
them into inventory, or to check stock that has been on the shelf for a
while. I even considered a jig to put reeled parts on to automatically
test and advance to the next cap, till it ran out or encountered a bad
part.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Fred_Bartoli]

ehsjr a écrit :

Good point. So your idea is to add a resistor,
or to abandon the switch or ?

To make it accept working under the cap bias.
Not that difficult.