Help need to Learn how to use an Oscilloscope

Discussion in 'General Electronics Chat' started by RodneyB, Mar 28, 2016.

  1. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    I have just received the Hantek 6022BE PC-Oscilloscope I have loaded the software and am ready to connect the Oscilloscope to my Desk top PC.

    I am trying to learn from the very beginning how to use the oscilloscope and what I can do to check that its working on the PC.

    I looked up information and I read that someone had connected it to a PC and when he connected the probe to the ground it burnt the unit so am rather nervous.

    Looking to getting started
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,638
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    Hello,

    Have a look at the XYZ of oscilloscopes.

    Bertus
     
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  3. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    Thank you. Is it safe to plug it in and try and test something like a voltage of my variable power supply
     
  4. ISB123

    Well-Known Member

    May 21, 2014
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    Did you calibrate it?
     
  5. MrSoftware

    Member

    Oct 29, 2013
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    Be careful where you connect the ground. Read the manual or use a multi meter to double check, but most likely the ground on the scope will be the same as mains ground. This means if you connect the ground to anything higher potential than mains ground, it would be a direct short. So be mindful of where you connect ground.
     
  6. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    From my experience, that is a quite good thing to learn upfront. Good piece of advice.
     
  7. paulktreg

    Distinguished Member

    Jun 2, 2008
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    I've damaged a USB scope in the past so be careful!

    The 0V is connected to mains earth in the computer ATX power supply and it's something you need to be aware off.
     
  8. Louis Wilen

    New Member

    Dec 22, 2015
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    As a first time scope user, there is often the temptation to connect a probe directly to 120 VAC mains power to see the power line sine wave. Don't do it!

    If you want to see waveform of mains power, attach the probe to the secondary of a small transformer, such as a "wall wart" that has A/C output.

    If you are going to be working on devices with switching power supplies, or working on very old radios, you'll need an isolation transformer that has been modified for "tech" use. For an explanation about this requirement, see:


    Enjoy that new scope. You'll learn a lot.
     
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  9. Louis Wilen

    New Member

    Dec 22, 2015
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    If you are referring to a lab type of variable power supply -- yes, it's fine to test the voltage using the scope, since the output of the variable power supply is isolated from the mains power.

    However, if you are referring to a Variac (autotransformer)-- no, do not connect the output of a Variac to the scope unless you use a separate isolation transformer between the mains power and the Variac.
     
  10. RodneyB

    Thread Starter Active Member

    Apr 28, 2012
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    I have never bought or used an oscilloscope so this is brand new to me
     
  11. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Hola Rodney,

    I recall recently watching my first long video by Dave (EEVblog) (usually they are LONG) precisely about this subject. A quite good recap on these matters. It is time well spent.

    Enjoy the scope.
     
  12. Louis Wilen

    New Member

    Dec 22, 2015
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    And again, to be perfectly clear, the isolation transformer has to be a "tech" isolation transformer. The earth ground must NOT be bonded to the neutral at the secondary. Most isolation transformers that are in a metal box come with the earth ground bonded to the secondary neutral. To use this type of isolation transformer as a "tech" isolation transformer, the secondary neutral must be unbonded from the earth ground. Of course, the earth ground MUST be maintained through the entire unit for safety reasons. The YouTube video from Todd that I referenced above explains how to convert a boxed isolation transformer to a "tech" isolation transformer.
     
  13. MrChips

    Moderator

    Oct 2, 2009
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    A common mistake inexperienced users make with an oscilloscope is improper connection of the GND clip on the scope or probe.

    Let us see how this can happen.

    Most of us (or some of us) know how to use a DMM to properly measure voltage. There are two leads, a RED lead and a BLACK lead.
    In order to measure voltage, we connect the two probes to two test points. The meter indicates the voltage difference between the two test points.

    An oscilloscope also displays voltage difference between two points, the tip of the probe and the GND clip. So one would assume that you need to connect the tip of the probe and the GND clip to the circuit being tested.

    Every oscilloscope I have ever encountered is already grounded to EARTH GROUND.

    If you are examining low frequency signals (such as audio frequency signals or other signals lower than 100kHz) there is no need to connect the GND clip. In other words, remove the GND clip and use the tip of the probe only to measure the voltage at the test point in your circuit. For this measurement to work, your circuit under test must also be grounded at EARTH GROUND. Applying this technique will prevent blowing out your oscilloscope or other pieces of equipment.

    For examining higher frequencies (greater than 100kHz) or logic signals, that is a different story. In order to properly observe a signal without inviting ringing and other artifacts, you need to connect the GND clip to the ground reference point physically closest to the signal being examined. Only connect the GND clip when you are absolutely certain that what you think is GROUND is exactly that - GROUND. Failing to do so will result in some undesirable and unpleasant consequences.
     
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