Braking Ground Loop - For Oscilloscope

Discussion in 'General Electronics Chat' started by Mad Professor, Mar 3, 2010.

  1. Mad Professor

    Thread Starter Active Member

    Apr 15, 2009
    Good Day All.

    I have a Picotech 2202 USB Oscilliscope, but I am having problems.

    When I am using my Main PC with the Oscilliscope I can not use the earth clamp on my probe otherwise my computer powers down.

    I understand the problems I am having are down to ground loops, from my computer and my bench power supply.

    I have tried having the mains cable on my PC and bench power supply going to the same master socket, and I have tried sockets other side of the room with the same problem.

    The only way I can get around the at this point in time is be using a old dell C400 (800mhz) laptop.

    But I really need and would like to be able to use my main pc and bench power supply with my Oscilliscope.

    From reading around the internet it seems I need something called "galvanic isolation"

    Can anyone advice what I can do about this.

    Thanks for your time.

    Best Regards.
  2. russ_hensel

    Well-Known Member

    Jan 11, 2009
    Not sure what a Main PC is, but most desktops ground the power supply to a true earth ground, while laptops often float. Try to figure out how yours is grounded. Then look at Picotech 2202 USB and how it is grounded, perhaps you can change the supply to it to use an earth ground. If not perhaps you can power the scope on a battery, which is easy to float. Finally the ground problem may come from the circuit you are trying to measure. Take a look at its grounding.