o-scope protection

Thread Starter


Joined Jan 18, 2021
Greetings. I just bought my first scope (Hantek DSO5202P Digital Storage oscilloscope 200MHz) and am learning how to use it. I don't want to fry it. For example, can I measure 120vac with the furnished probe, or do I need a higher impedance probe, e.g. 100:1?

Any other "Don't fry your scope" tips appreciated. Thanx.


Joined Jul 10, 2017
Look up the specifications for the Oscilloscope. It will specify the maximum AC and DC voltages for the vertical input. It will also specify the vertical deflection ranges in volts per division.
If I take the time to find the operating manual online and use it to answer your questions, you will have forgotten by the next time you want to use the scope. If you download it, you can learn all the limitations of the instrument yourself and you will have it for future reference.


Joined Apr 21, 2014
As others have said, the oscilloscope specifications will dictate the maximum input voltage for a direct connection - i.e., a simple wire. If using any type of probe, you have to consider the specifications of the probe as well.

For example, a 1:1 probe has to withstand the input voltage and CAT rating. Also, since the probe in this case does no attenuation, the input voltage and CAT rating of the oscilloscope inputs must meet the voltage source.

If a 10:1 probe rated for CAT I 500V is used, you need to look at its specifications sheet to see the voltage derating curve for the input frequency - something like the curve below. Typically for the 50/60Hz frequency of mains, no derating is needed. Also, in this case, the oscilloscope input will operate at a much lower rating as the voltage is divided by 10.


Additional details at this recent discussion:


Joined Aug 21, 2008
Read the manuals for the scope and the probes.
Read the manuals for the scope and the probes.
Read the manuals for the scope and the probes.
Read the manuals for the scope and the probes.
You should get the idea.


Joined Jul 10, 2017
Oscilloscope specifications can be a little confusing if you are not fully aware of the terms they use. If there is anything in the specification that you don't understand, let us know and we will explain it for you.