Electronics > Beginners

Is this scope working properly

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Rakcom:
Hi,
I am in my second year of Electrical Engineering and I have just received my first proper scope. A Hantek DSO5072P (I also have a Pokit https://pokitmeter.com/)

Today I have been playing around with it and the Pokit by looking at a 0.5kHz square wave generated by a Raspberry Pi 3B+.


This is what they have shown
The Hantek:


The Pokit:


I have also included the excel files that I got from the csv files that both have given me.

What I find strange is that the Hantek peaks at 3.7V while the Pokit peaks at a more reasonable 3.37V. Both show a steady state at 3.3V
Both are DC coupled, in their normal mode, the Hantek has been calibrated, the Pokit is the 1MSps version, and I have kept their leads as straight as possible.

My question is there a way to fix the Hantek, should I return it, or is the Pokit lying to me and this 0.4V spike is normal?

Tom45:
It looks like you need to adjust the Hantek's probe compensation.

Rakcom:
I just switched the probes to 1X mode and that fixed it

At Uni only a few of our probes have that selection slider so I seemed to have forgotten on it.

Thanks

Tom45:
While switching from 10x to 1x solved the immediate problem that you were seeing, in the long term you need to understand what is going on with scope probes.

Your probe in 10x mode would have worked equally well if it had been compensated. And more to the point, a 10x probe will have higher frequency response and put less loading on your circuit. In most cases, a 10x probe is what you will normally be using.

Do a search for oscilloscope probe compensation to learn about probe compensation. A good example is:

 

The video is by W2AEW who is a Tektronix employee and is active on eevblog as well as being a good teacher.

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