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Homebrew HV hiZ scope probe

Discussion in 'Electronic Design' started by TheGlimmerMan, Oct 20, 2012.

  1. Fred Abse

    Fred Abse Guest

    I got the catalog from the Ohmite site the same time this thread started.
    Took a bit of digging.

    Don't you have a proper LCR meter, or bridge? A DMM isn't really suitable
    for measuring parasitic capacitance.

    A "real" LCR meter, or impedance analyzer, is a must-have for any serious
    work. You could use an old Q meter instead.
     
  2. Fred Abse

    Fred Abse Guest

    I've just reread the PDF, and beg to disagree.

    "Probe 1Gohm-3.jpg" shows the step still rising at about 1.8 microseconds,
    where it goes off screen.

    Risetime is the time from 10% to 90% *of the final steady value*. Risetime
    is at least 1.2 microseconds, possibly more. It doesn't show the final
    value.


    "Probe 1Gohm-3.jpg" doesn't contain enough information to calculate
    risetime. It just shows the initial overshoot and ringing, ie. the
    first half-centimeter of the previous photo,some of what you see will be
    due to the cable.

    What I see is an under-compensated probe.
     
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