Maker Pro
Maker Pro

Where are all the ESR meters?

J

John Larkin

Jan 1, 1970
0
Without pencil to paper, synchronous _may_ allow separation of real
and imaginary terms.

...Jim Thompson

Without pencil to paper, I know it will separate the real and
imaginary components enough to improve ESR resolution substantially.

1 uF at 100 KHz has a reactance of 1.6 ohms; you don't need a pencil
to figure that out!

John
 
D

Don Bowey

Jan 1, 1970
0
Without pencil to paper, I know it will separate the real and
imaginary components enough to improve ESR resolution substantially.

1 uF at 100 KHz has a reactance of 1.6 ohms; you don't need a pencil
to figure that out!

John

Go stand in the corner for 15 minutes. You are getting entirely too pisssy.
And don't do THAT in the corner.
 
J

John Devereux

Jan 1, 1970
0
J

John Larkin

Jan 1, 1970
0
I think that the medium is more the problem than what the
people involved can or cannot play at. Try using an
archived text posting medium for your next brainstorming
session and see how that works out.

I posted a couple of half-baked ESR meter schematics. A couple of
people riffed on them constructively.
We are using a poor tool for this job.

Or poor players. I'd think the idea of brainstorming in public would
appeal to some people, like a trapeze act without a net. Looks like I
was wrong.

John
 
J

John Larkin

Jan 1, 1970
0
Go stand in the corner for 15 minutes. You are getting entirely too pisssy.
And don't do THAT in the corner.

OK, I'll stand while these guys dance around the problem.

John

noting that 10 mA into 1 mohm is 10 microvolts, still pencil-free.
 
J

John Larkin

Jan 1, 1970
0
Not being a designer, I won't participate (and you wouldn't want me to!) in
the process. But please consider that an ESR meter can -- if designed with it
in mind -- be handy at measuring things such as resistance of battery cells,
giving indication of relative age. With the dozens of rechargeable AA cells
lying around, I want to know how they're getting on in years...

A small problem is that if you put in diode protection, measuring cells is
out unless you decide to switch the protection on and off. Or come up with a
more elegant solution...

If it's all AC coupled, it could be protected from reasonable hazards
and do batteries, too.

If the frequency could be swept, it could analyze power supply output
impedances, too. Nice for stability analysies.

John
 
C

Chris Jones

Jan 1, 1970
0
John said:
Interesting that for a proposed "group design", hardly anybody is
willing to make a first step. The psychology of group design is
fascinating, and it turns out that an audience is a huge inhibition;
people tend to not expose ideas if they fear they are imperfect, and
might give some nit-picker grounds for public criticism.

Brainstorming is delicate because people are fragile. At my place, we
scribble goofy ideas on a whiteboard, do a lot of stupid stuff (don't
distinguish between circuit-as-proposal and circuit-as-joke), argue
and laugh a lot, and sometimes come up with brilliance, with no way to
tell who gets the credit. Some people just can't play at this game.

John

Look, I already have a perfectly good ESR meter that I built from a kit
designed by Bob Parker. You can talk to him about it, he is on
aus.electronics and is helpful. I don't feel the need to reinvent the
wheel, especially because it is a good wheel. It would be very hard to
design an ESR meter that would be of more use in practical situations.

If I had the time to play with this stuff, I would be trying to design a
proper VNA with 12 term correction that will go up to >3GHz, that seems not
to have been done yet in the homebrew world.

Chris
 
S

Spehro Pefhany

Jan 1, 1970
0
OK, I'll stand while these guys dance around the problem.

John

noting that 10 mA into 1 mohm is 10 microvolts, still pencil-free.

That's a nice juicy signal to work with.

Best regards,
Spehro Pefhany
 
S

Spehro Pefhany

Jan 1, 1970
0
If it's all AC coupled, it could be protected from reasonable hazards
and do batteries, too.

If the frequency could be swept, it could analyze power supply output
impedances, too. Nice for stability analysies.

John

A really robust design might allow you to check the ESR of the line
voltage caps in an operating SMPS, though I'm not sure I'd want to go
that far.

Best regards,
Spehro Pefhany
 
M

Michael A. Terrell

Jan 1, 1970
0
Winfield said:
Michael, I'm sorry to hear your health problems have become
so severe. I was hoping the VA would get you back on track,
but now I wonder if they've diagnosed you properly? Could
it be that at this point you're suffering more from the cure
(medications) than the illness?


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. My
doctor (at least the current one) agrees that my teeth all have to come
out. I have had a problem with low level infections most of my life.
This infection is in my jawbone, at the roots of my teeth.

Under a law passed by congress, teeth are NOT a medical issue. Well,
at least for Veterans. Period. End of story. Don't you even think
about asking us again! OTOH, these same morons can got into any
military medical facility at any time they want, and get free dental
care. They don't need appointments, and can cut in front of any
soldier's health care, unless they are surgery.

There are three very small groups of Veterans that are granted dental
care:

1: Just discharged from active duty, and no care was available where
you were stationed.
2: You were being treated when you were discharged. They will continue
care for a brief period.
3: Homeless for over 60 days.

The VA will do the work if you can pay their price in advance, or
sign papers to allow it to be deducted from your disability pension.
Their rate is higher than some private practices. If I let them do the
work, I would be homeless.

I had oral surgery to remove a hollow stump that was cutting my
tongue a few months ago, thanks to some friends that got together and
raised the money. The oral surgeon that did the work refuses to pull
the nine remaining teeth because he can't see any reason for them to
cause pain. He said it was just the nerves in the jaw bone being
affected by the one infected tooth. He was wrong. Not that it matters,
because there is no way I can afford the $250 per tooth, for nine
teeth. That is over 20% of my income for the year.

The County health office refused to help, because "We only treat
women and children's dental problems.". (Plus all of the illegal
aliens.) They didn't want to give me any help at all, because "Oh, you
know that the Federal government takes care of everything for you vets,
and we have to help all these unmarried women (and their illegitimate
kids)!".

The state dental college in Gainsville is no help. Their prices
aren't that great, its a several hour trip, and they play a daily
lottery to see who gets treated that day.

As the infection level changes, it affects the blood sugar and
pressure, and causes more or less swelling in my legs. While I was on
antibiotics to prepare for the oral surgery the swelling went completely
down, and all the pressure sores dried up in under 48 hours. I had to
stop taking all my medications, but my blood sugar and pressure were
almost normal without them. The constant pain and numbness in my left
hand and arm was barely noticeable. My vision was the sharpest it had
been in years.

In spite of all this, the VA isn't allowed to do what's needed. They
spent more on additional medications last year than it would have cost
to do the dental work. About $6,000 more.


--
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
 
J

Jim Thompson

Jan 1, 1970
0
That's a nice juicy signal to work with.

Best regards,
Spehro Pefhany

Sno-o-o-ort! But it'll use a uP ;-)

...Jim Thompson
 
D

Don Bowey

Jan 1, 1970
0
On 7/23/07 1:18 PM, in article [email protected],

(snip)
OK, I'll stand while these guys dance around the problem.

John

noting that 10 mA into 1 mohm is 10 microvolts, still pencil-free.

But.... But.... This project is unmanaged and totally voluntary. It's
worse than a Standards meeting. Axes to grind notwithstanding. Under the
circumstances, I thought it was moving along somewhat. Lots of latitude is
needed unless some rules are formed for handling contributions.

I'm learning a bunch and have only one contribution. It is that posts that
argue against designing the device should be considered TOTALLY out of
order. It appears to me to be a project for those who "can do" and want to
do. All others can remain (or start to be) silent.

Whoever suggested the project did a brilliant thing.
 
M

Michael A. Terrell

Jan 1, 1970
0
Fred said:
It is more than apparent from your posts that newsgroup is on the whole
a disturbing influence for you and may not be the best thing for your
health. You should abandon it and put that time into a support group.


Golly gee, Ferddie! Just where would I find this support group for
"Congress is practicing medicine, on me?" and has no damn idea what
they're doing?

Why don't YOU abandon usenet and join a support group for "I only
think I'm superior to everything else in the known universe"?


--
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
 
W

Winfield Hill

Jan 1, 1970
0
Yes, of course -- required.
OK, I'll stand while these guys dance around the problem.

John

noting that 10 mA into 1 mohm is 10 microvolts, still pencil-free.

Yes. Since I've got gain and synchronous detection,
10uV should be fine. I'm planning using a 199.9mV FS
Datel panel meter (low power), so for a 2-ohm range,
with 1 mill-ohm resolution, a G=10 instrumentation
amplifier will be OK (an extra x1.414 for RMS will be
squeezed in someplace). G=100 would provide 0.1m
resolution, but there'll probably be a fair amount
of noise and drift, etc., anyway.

Initially I had considered 100mA drive, but that'd be
hard on the battery, and worst-case capacitor-discharge
current would be 10x higher. Course, we could add a
depletion-mode limiter, as you suggested...
 
J

John Larkin

Jan 1, 1970
0
Yes, of course -- required.


Yes. Since I've got gain and synchronous detection,
10uV should be fine. I'm planning using a 199.9mV FS
Datel panel meter (low power), so for a 2-ohm range,
with 1 mill-ohm resolution, a G=10 instrumentation
amplifier will be OK (an extra x1.414 for RMS will be
squeezed in someplace). G=100 would provide 0.1m
resolution, but there'll probably be a fair amount
of noise and drift, etc., anyway.

Initially I had considered 100mA drive, but that'd be
hard on the battery, and worst-case capacitor-discharge
current would be 10x higher. Course, we could add a
depletion-mode limiter, as you suggested...

One concern will be inductive coupling in the 4 leads going out to the
DUT; that could easily bash a lot more than 10 uV into the sense
circuit. If it can really do values like a milliohm, the leads will
have to be done right, too.

What's the sinewave source? Are you going to trim the phase of the
drive into the phase-sensitive detector? To get good capacitance
rejection, the phase will have to be spot-on.

John
 
J

John Larkin

Jan 1, 1970
0
I like that one, John. Now how about the IN amp?
Maybe the AD8220, but I'd like more common-mode
range.

If you're working at a fixed 100 KHz, how about using a transformer?
You'd get absurd common-mode range and some decent voltage gain for
free. Maybe even tuned, with a trimmer cap that fine-tweaks the system
phase alignment.

John
 
J

Joel Kolstad

Jan 1, 1970
0
Michael,

I'm sure you'd disagree with him about a lot of things, but if you have the
opportunity, you'd probably enjoy watching Michael Moore's latest film,
"Sicko." He has various cases similar to yours in there -- folks like 9/11
rescue workers who were *volunteer* EMTs, and as such there was no one
interested in patching them up after, e.g., burning their lungs out digging
through the debris of the twin towers. Sadly, it appears as though you'd be
getting better care right now if you were a Canadian, Englishman, or possibly
even a Cuban rather than a U.S. Citizen.

Hey, if we come up with a decent ESR meter design, perhaps you could assemble
& sell them and make enough money on the side to cover some of your medical
needs.

This wouldn't work for you, but there's a Michigan? woman in Sicko who just
crosses the border into Canada and gets medical treatment there by listing a
friend of hers as her common law husband.

---Joel
 
T

Terry Given

Jan 1, 1970
0
Michael said:
So, you want to flash the silver off the contacts to metalize the
insides of the switch's body, or even weld them together?

no, I assumed you werent stupid enough to actually do that, and would of
course include some R, as John D. pointed out. Merely illustrating how
to move the switch out of the measurement path, to achieve the same
objective.

Cheers
Terry
 
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