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  • nonpolarized caps

    From john larkin @21:1/5 to All on Sun Mar 9 15:02:48 2025
    I need some nonpolarized caps, ballpark 10uF or so, +-50 volts. There
    are some nonpolar aluminums.

    Any experience or advice?

    Polymer caps all seem to be polarized. Films are too big. Ceramics are
    big and nonlinear.

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  • From Klaus Kragelund@21:1/5 to john larkin on Sun Mar 9 23:43:49 2025
    On 09-03-2025 23:02, john larkin wrote:
    I need some nonpolarized caps, ballpark 10uF or so, +-50 volts. There
    are some nonpolar aluminums.

    Any experience or advice?

    Polymer caps all seem to be polarized. Films are too big. Ceramics are
    big and nonlinear.





    You can place THT films over the SMD components, so no space occupied ;-)

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  • From john larkin @21:1/5 to klauskvik@hotmail.com on Sun Mar 9 16:36:43 2025
    On Sun, 9 Mar 2025 23:43:49 +0100, Klaus Kragelund
    <klauskvik@hotmail.com> wrote:

    On 09-03-2025 23:02, john larkin wrote:
    I need some nonpolarized caps, ballpark 10uF or so, +-50 volts. There
    are some nonpolar aluminums.

    Any experience or advice?

    Polymer caps all seem to be polarized. Films are too big. Ceramics are
    big and nonlinear.





    You can place THT films over the SMD components, so no space occupied ;-)

    This isn't horrible:

    https://www.digikey.com/en/products/detail/wima/MKS2B046801M00JSSD/9370550

    I have height available but very little board area, and this one is
    pretty good.

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  • From legg@21:1/5 to All on Mon Mar 10 08:49:47 2025
    On Sun, 09 Mar 2025 15:02:48 -0700, john larkin <jlArbor.com> wrote:

    I need some nonpolarized caps, ballpark 10uF or so, +-50 volts. There
    are some nonpolar aluminums.

    Any experience or advice?

    Polymer caps all seem to be polarized. Films are too big. Ceramics are
    big and nonlinear.


    and nonpolar Aluminums are too . . . ?

    For what kind of service use? Ripple current? Frequency?

    Back-to-back 100V polymers, center-biased to -50V?

    It's too far from Christmas to go and ask Santa Claus.

    RL

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  • From john larkin @21:1/5 to legg on Mon Mar 10 08:30:49 2025
    On Mon, 10 Mar 2025 08:49:47 -0400, legg <legg@nospam.magma.ca> wrote:

    On Sun, 09 Mar 2025 15:02:48 -0700, john larkin <jlArbor.com> wrote:

    I need some nonpolarized caps, ballpark 10uF or so, +-50 volts. There
    are some nonpolar aluminums.

    Any experience or advice?

    Polymer caps all seem to be polarized. Films are too big. Ceramics are
    big and nonlinear.


    and nonpolar Aluminums are too . . . ?

    For what kind of service use? Ripple current? Frequency?

    Output filter in a 8-channel bipolar switching power supply. The PCB
    layout will be crazy dense.


    Back-to-back 100V polymers, center-biased to -50V?

    It's too far from Christmas to go and ask Santa Claus.

    RL

    I asked for experience and advice, not snark.

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  • From john larkin @21:1/5 to All on Mon Mar 10 10:12:47 2025
    On Mon, 10 Mar 2025 17:33:59 +0100, Gerhard Hoffmann <dk4xp@arcor.de>
    wrote:

    Am 10.03.25 um 16:30 schrieb john larkin:

    I asked for experience and advice, not snark.

    I have used these WIMA capacitors (10uF version) in the input
    of an ultra low noise FET amplifier. Absolutely no complaints.

    Gerhard



    Yeah, film is ideal if I can make them fit. As noted, the board will
    be crazy dense. My production and test people might make funny faces
    if I suspend giant axial power resistors and caps above surface-mount
    parts. How about a baby board on hinges?

    The design is actually an 8-channel programmable dummy load that
    simulates both resistance and inductance. But it occurred to me that,
    having eight isolated bipolar-output class-D amps, we could futz with
    the output filtering and get an 8-channel power supply from the same
    PCB layout.

    I've wondered if the bipolar aluminum caps work right after being DC
    biased one way for a long time.

    There is one dirty trick of putting two alum caps in series opposing,
    with a diode across each to prevent back-bias. That's crazy nonlinear
    but might be OK as a power supply filter.

    Maybe jamming film caps on the board is best.

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  • From Gerhard Hoffmann@21:1/5 to All on Mon Mar 10 17:33:59 2025
    Am 10.03.25 um 16:30 schrieb john larkin:

    I asked for experience and advice, not snark.

    I have used these WIMA capacitors (10uF version) in the input
    of an ultra low noise FET amplifier. Absolutely no complaints.

    Gerhard

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