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  • ? on old electrolytic caps

    From amdx@21:1/5 to John Fields on Mon Mar 1 07:54:56 2021
    On 6/19/2014 2:18 PM, John Fields wrote:
    On Thu, 19 Jun 2014 17:19:00 +0000 (UTC), Cydrome Leader <[email protected]> wrote:

    Maynard A. Philbrook Jr. <[email protected]> wrote:
    In article <[email protected]>,
    [email protected] says...
    The resistance of a capacitor is an entirely different thing, and
    amounts to the leakage current measured through the dielectric with
    a voltage across it.

    In terms of goodness, the lower the ESR and the higher the
    resistance the better.

    John Fields

    Could you please clarify that a bit? I am only an
    inbred from Maine and I did quite get that one.
    If you take an electronic device, even something simple like a battery
    there are still losses inside the device from the wiring, connections and
    other electrochemical stuff going on inside the device.

    Those internal losses are what's called ESR. For instance, if you short
    out a AAA battery you will get less current than if you short out a D
    cell, even though both can in theory output 1.5V. The D cell has beefier
    internal construction and offers a lower internal resistance, so more
    current can be drawn from it.

    The tricky part is a battery, (or capacitor or anything really) is not a
    plain resistor, so you can't measure this "equivalent" value with an ohm
    meter, but if you could, the result would be the ESR.

    In capacitors, you generally want the lowest possible ESR. A cap with a
    high ESR is old, failing, cheap or just junk, and it can potentially heat
    up during use, just like a resistor. Heat makes electrolytic capacitors
    dry up, which increased the ESR, which make them heat up more, until they
    explore or just stop being capacitors.
    ---
    Right.

    They turn into explorers. ;)

    John Fields

      The third picture (schematic) has a slightly simplified schematic of
    a capacitor with it's ESR, leakage and inductance.

    https://www.designworldonline.com/basics-of-tantalum-electrolytic-capacitors/
     I think this may help you understand, and why, each must be measured differently.

                                      Mikek


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  • From amdx@21:1/5 to amdx on Mon Mar 1 09:55:38 2021
    On 3/1/2021 7:54 AM, amdx wrote:
    On 6/19/2014 2:18 PM, John Fields wrote:
    On Thu, 19 Jun 2014 17:19:00 +0000 (UTC), Cydrome Leader
    <[email protected]> wrote:

    Maynard A. Philbrook Jr. <[email protected]> wrote:
    In article <[email protected]>,
    [email protected] says...
    The resistance of a capacitor is an entirely different thing, and
    amounts to the leakage current measured through the dielectric with
    a voltage across it.

    In terms of goodness, the lower the ESR and the higher the
    resistance the better.

    John Fields

    Could you please clarify that a bit? I am only an
    inbred from Maine and I did quite get that one.
    If you take an electronic device, even something simple like a battery
    there are still losses inside the device from the wiring,
    connections and
    other electrochemical stuff going on inside the device.

    Those internal losses are what's called ESR. For instance, if you short
    out a AAA battery you will get less current than if you short out a D
    cell, even though both can in theory output 1.5V. The D cell has
    beefier
    internal construction and offers a lower internal resistance, so more
    current can be drawn from it.

    The tricky part is a battery, (or capacitor or anything really) is
    not a
    plain resistor, so you can't measure this "equivalent" value with an
    ohm
    meter, but if you could, the result would be the ESR.

    In capacitors, you generally want the lowest possible ESR. A cap with a
    high ESR is old, failing, cheap or just junk, and it can potentially
    heat
    up during use, just like a resistor. Heat makes electrolytic capacitors
    dry up, which increased the ESR, which make them heat up more, until
    they
    explore or just stop being capacitors.
    ---
    Right.

    They turn into explorers. ;)

    John Fields

      The third picture (schematic) has a slightly simplified schematic of
    a capacitor with it's ESR, leakage and inductance.

    https://www.designworldonline.com/basics-of-tantalum-electrolytic-capacitors/

     I think this may help you understand, and why, each must be measured differently.

                                      Mikek


    I must have reversed my date orientation when I answered this. Then I
    noted John Fields name and thought,

    I think he died!    Anyway, I made a fine contribution to a 6 year old thread.

    Mikek


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