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Where are all the ESR meters?

Discussion in 'Electronic Design' started by Fred Bloggs, Jul 21, 2007.

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  1. Fred_Bartoli

    Fred_Bartoli Guest

    The Phantom a écrit :
    There are two related:
    - euphemism, which consist of understating to 'soften' what you say.
    - litotes, which consist of saying less to imply more.
     
  2. Winfield

    Winfield Guest

    Perhaps a better question is, how big is big?

    Several designs we've been considering have a
    pair of diodes to discharge the test capacitor
    and limit the circuit voltages, but I've heard
    these can fail with large, charged capacitors.

    I think the issue isn't necessarily how high
    the voltage (tube amplifiers get to hundreds
    of volts), or how high the current delivered,
    but how much energy is going to be dissipated
    in the protection components that discharge
    the guilty capacitor.

    I'd say the answer is, the size of two fists.
    I think we're talking about ~ 100J of energy.
    Isn't that more than enough to blow out a
    common glass diode and/or a 1/4-watt resistor?
     
  3. Jim Thompson

    Jim Thompson Guest

    Should be enough to crank you over a few times ;-)

    ...Jim Thompson
     
  4. Fred Bloggs

    Fred Bloggs Guest

    What does your physical disability have to do with a complete absence of
    any constructive circuit contributions to SED?
     
  5. Fred Bloggs

    Fred Bloggs Guest

    WH is stalling... input protection has little to do with a basic
    measurement architecture. I had no idea this little project would be so
    difficult for everyone:)
     
  6. Jim Thompson

    Jim Thompson Guest

    I know ;-)

    ...Jim Thompson
     
  7. John Larkin

    John Larkin Guest

    If it's a 4-terminal gadget, all you need to do is current-limit three
    of the leads. My pfet current source does that inherently, with an
    added diode for the other direction. Or spring for a few of those
    Supertex depletion fets, or the protected SSRs.

    I think the protections can be added once an architecture is settled
    on. Basic issues:


    Analog/needle or digital/uP?

    Simple scalar impedance, or tease out the resistive component, or
    resolve both real and imaginary parts?

    Fixed or variable frequency?

    Measure anything else? Capacitance? Resistance? Inductance?

    Time or frequency domain?

    John
     
  8. John Larkin

    John Larkin Guest


    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
     
  9. John Larkin

    John Larkin Guest

    Hey, Fred, post an ESR circuit!

    John
     
  10. Jeff L

    Jeff L Guest

    Protection is easy - read the voltage across the cap in question with a
    comparator, if it is more then a few volts, have a indicator displayed to
    discharge the cap first. If it is below a few volts, connect the cap to the
    metering circuitry with a couple of low RDS on FET's.
     
  11. 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.

    We are using a poor tool for this job.
     
  12. Fred Bloggs

    Fred Bloggs Guest

    Most definitely, and primarily to elicit critique from "Michael
    Terrell," a self described "I never claimed to be a circuit designer"
    type, who is always long on superficial opinion and woefully short of
    usefulness.
     
  13. Fred Bloggs

    Fred Bloggs Guest

    Well whatever...the task is straightforward and does not require a great
    amount of ingenuity. The ingenuity comes in deciding the functionality
    of the meter. In my opinion there is nothing to accomplish by going half
    way to an impedance analyzer, there are already plenty of compact and
    fully functional products in that niche. The key is to produce the
    simplest possible design that measures ESR, if something else comes free
    along with that without introducing one iota more of complexity then
    fine, but if it requires one speck of dedicated hardware not useful for
    determining ESR then it goes. This will require that you discover
    something inherent to ESR that allows for a very simple circuit
    architecture. That is all the help I am going to give you at this stage:)
     
  14. John Larkin

    John Larkin Guest

    Thanks for the excellent illustration of my point. You are far more
    concerned about your ego than you are about the technology. Probably
    that explains why you don't design electronics.

    There's a great irony here; that is all the help I am going to give
    you at this stage.

    John
     
  15. John Larkin

    John Larkin Guest

    Don't post it to elicit criticism. Post it to elicit suggestions,
    improvements, riffs, history, amazement.

    John
     
  16. john jardine

    john jardine Guest

    Analogue, 0 to 1 ohm resistance (linear down to a few mohms), in series with
    1uF and above.
    Discharge protection, Kelvin sensing etc, just added fluff. It's a core idea
    that will offer the interest and Laurels.
    Q's of even a 100 require a board full of bits. The ESR problem is up in the
    1 part in a 1000 area.
    Fred seems to have something up his sleeve. I'm intrigued :)
     
  17. DaveC

    DaveC Guest

    Measure anything else? Capacitance? Resistance? Inductance?

    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...
     
  18. Winfield

    Winfield Guest

    Right. I know, because I *have* been cranked,
    more than once. :-(
    I'm not stalling; my paper sketches nicely handle
    the protection requirements I posted. Basically
    my design is a simplified version of the HP meters
    I have, based on the fact that 5% accuracy is good
    enough. I've been slowed down a bit by the need to
    evaluate single-supply instrumentation amplifiers,
    etc. And by my real projects: working on the book,
    home projects like my rust-infected Japanese Kerria,
    my Honeysuckle arbor, and of course, my Harvard job,
    with 1T generators, TEC drivers, -- things like that.
     

  19. Well, Fred, you claim to be in perfect health, yet you haven't even
    submitted a set of specifications for YOUR ESR meter design. On the
    other hand, you've already dammed designs of others you hadn't even
    seen.


    As far as your questioning what my disabilities have to do with
    anything proves once again just what a fucking asshole you are. You
    have no idea how bad my health is but like everyone else here, your over
    inflated ego MAKES you damn everything and everyone in sight.

    I'll tell you what. Go buy a cane. Strap 75 pounds on your back and
    try to do the usual day to day things you HAVE to do to survive. Cut 15
    to 20 weeping sores on your legs, and try to get by on no quality sleep,
    at all. I don't really sleep anymore. I pass out from exhaustion. Try to
    breathe through several layers of mask so you're always short of breath.
    Then exert yourself till you feel faint.

    There is no way you can simulate most of the side effects of all the
    medications. About the only one you can get close to is to alternate
    between Magnesium Citrate and Imodium A-D, several times a day. How
    would you like to go from starting the day constipated, with a stool so
    hard that your ass bleeds, to diarrhea and back to constipated in a
    single day?


    If I DON'T take ALL of the medicine I can get some sleep, but both my
    blood pressure and blood sugar go sky high. I generally have less than
    two hours a day to do anything that requires concentration and/or
    exertion, so why waste it on a circuit design I can't afford to build?

    I WAS working on a design for a computer interfaced ESR meter to
    allow quick go/nogo or incoming inspection testing to read both the
    capacitance and ESR, and see if they were in spec, when I lost my job on
    Sept. 7th, 2001. I was already so sick I couldn't function, and people
    laughed in my face when I applied for work. I was stopped by a cop one
    day and accused of being drunk, because I couldn't walk a straight
    line. Even walking with the cane, assholes like you do their best to
    block my way, or try to knock me down. On punk tried to take my cane,
    but soon regretted it because his arm was twisted into a knot behind his
    back. he was on his knees, begging me to let go. He had ignored my good
    right arm that still works, so I grabbed the other end of the cane and
    twisted it, and his arm behind his back and pined him so he couldn't let
    go.

    I had to wait over two years to get any medical help from the VA.
    During that time I lost so much strength that I couldn't walk. Even
    though I was eating under 1200 calories a day, I put on over 100 pounds.
    I topped out at 297 pounds. So far, I have lost 25 pounds, in the last
    two years. Its going to take a long time to ever get close to the
    normal 180 pounds I was, before I got sick.

    You have no damn idea what its like to be severely disabled and a lot
    of fucking nerve. Have you EVER heard of anyone else who got 100%
    disability in less than two months? Does that tell your pea brain
    anything, at all?


    --
    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
     
  20. ehsjr

    ehsjr Guest

    Just use a spring return spdt toggle.
    Toggle to test.

    Ckt ---o
    o<--o---- to DUT
    |
    Gnd ---+-------- to DUT
     
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