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capacitance load of oscilloscope probes

Discussion in 'Electronic Equipment' started by Blue, Apr 6, 2010.

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  1. Blue

    Blue Guest

    I am looking for oscilloscope probes. There are a number of choices on
    ebay. I am looking for passive 1x/10x probes for a 60 MHz scope with
    input capacitance of 30 pF.

    One of the choices is a probe with capacitance that can be changed from
    15-40 pF. Its capacitance load is 90pF/20pF (I assume for the two
    attenuations). Would this be okay with the scope? Any other pointers
    what to keep in mind wrt to the capacity of the probes?

  2. Blue

    Blue Guest

    Thanks. I was reading a bit more about probes and realized that the
    variable capacitor on the probe is used to cancel the scope's input
    capacitance. Hence the former should have the latter within its range.
    However, that leaves us with the probe's own capacitance. In this case,
    it is 90pF/20pF (for 1:1/1:10 attenuation). Are these values typical for
    probes for 60 MHz scopes?
  3. Blue

    Blue Guest

    Okay, thanks for the explanations.

    One more point I just was wondering about. Is it typical that probes for
    different bandwidths have same capacitance? e.g. should a 60 MHz probe
    have the same capacitance as a 200 MHz probe? I am suspecting that
    higher frequency probes are going to have lower capacitance else higher
    freqs are going to be attenuated more. But I could be wrong, because
    based on your explanation, at 1:1 all probes are going to have the same
  4. StepNfetchit

    StepNfetchit Guest

    Many good o'scope and probe tech and learning pdf's at the following
    including Tektronix ABC's of probes:
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