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  • Oscilloscope isolation

    Er_Mahendran

    Member

    Updated: Oct 25, 2024
    Views: 1.4K
    Hello guys,
    Can anybody explain the need for isolating the oscilloscope? If not isolated what will happen? Explain in detail.

    Thanks in advance!
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Replies

  • debu

    Member • Jul 17, 2009

    @Er_Mahendran: Isolation reduces the chances of creating a Ground Loop. <a href="https://en.wikipedia.org/wiki/Ground_loop_%28electricity%29" target="_blank" rel="nofollow noopener noreferrer">Ground Loop %28Electricity%29</a> can explain the problem in more detail then I.

    Hope this helps,

    Regards,

    Debu 😀

    Edit: Tektronix also has a beautiful note on this topic #-Link-Snipped-# which is more specific to oscilloscopes.
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  • Er_Mahendran

    Member • Jul 17, 2009

    Hello Debu,
    Thanks for your reply. Now I got some idea about ground loop. Can you explain how the oscilloscope ground looping is eliminated by isolating the scope or device under test. Please explain in laymann way.

    Thanks in advance.
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  • debu

    Member • Jul 17, 2009

    @Er_Mahendran: The link I posted from Tektronix explains this in a lot of detail. In Laymen terms;

    The following image shows the problem. The ground for the tested circuit is connected to the testing device at two points. This leads to different ground potentials, and hence the problem as stated before.
    [​IMG]
    (image taken from #-Link-Snipped-#)

    As is obvious, the simplest remedy for the aforementioned problem is, to disconnect the ground at either of the two places. Now; it is not feasible to disconnect the ground from the test side. The reason being, the supply ground may not always be common. Hence, we choose to isolate the scope.

    Hope this helps,

    Regards,

    Debu 😀
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  • silenthorde

    Member • Jul 19, 2009

    Even the choice of proper probe is extremely important. Probes introduce resistive, capacitive and inductive loading errors in the system.

    Capacitive loading results in increase in rise time and decrease of BW.

    Inductive loading results in oscillations in the oscilloscope o/p.
    Yale's EE lab website has great resource on oscilloscope probe. heres the link #-Link-Snipped-#
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  • Er_Mahendran

    Member • Jul 19, 2009

    Hello Debu,
    Thanks for your reply. It is much useful.
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