Can you measure 220v ac with DSO138 ?

How to view the mains ac voltage waveform with the cheap DSO138 battery powered oscilloscope.

[claudiosantana]

Nice and clear, was looking for a explanation

[tristankhan]

Exactly what i was looking for. Thanks for uploading. Cheers

[newstar]

You should have handle the scope carefully while connecting to main AC especially the exposed BNC connector

[randersson]

I was thinking about buying one and after this video I'm sure. Thank you,

[macmccune]

Thumbs up solely for the DIY connector!

[complexity]

Thanks for showing that (distorted) sine wave. I think I'll try another higher model. I'm guessing that the display can't do the zoom in and zoom out. I'm on 110V, but this is still a great test.
Thanks.


P.S. I scrolled through your other videos, just to browse. Your Klipper install video is a rare find (because you're using XFCE and Linux).

[Dennis-mqor]

You really have a lot more to learn about using that scope.
You are not going to get accurate amplitude readings when the signal is greater than what you can fit on the screen of that scope. It also requires the display of a minimum of one complete cycle, (but if you show 2 or 3 complete cycles your measurements will be much more accurate).
That unit has an internal 12 bit analog to digital converter in it, while most of the much more expensive scopes are only using an 8 bit analog to digital converter.
Also, you should re-calibrate it every time you turn it on, and re-calibrate it again after it reaches operating temperature.
The calibration procedure requires grounding the input. (in this case your 10X probe), and hitting a few buttons to set the reference ground level for the scope.
Without the 10X probe, the scope can handle + and - 50 volt swings from zero, (100 volts Pk to Pk), and with a 10X probe it can handle ten times as much or 1000 volts pk to pk. A 220 VAC sinewave is typically about 620 Volts pk to pk, so it should be able to measure it.
For DC measurements and pk to pk measurements you can multiply your readings by ten to get the correct reading, but if a calculation requires squaring, you can't do that because squaring is not the same as multiplying by 10. (RMS measurements require
They do make scope probes that can do 10X and 100X, which would be perfect for that tiny scope. but even the more common 1X and 100X probe can be used with it to guarantee that you can keep those ac peak values from overshooting the scope screen..
Once you get more familiar with that scope you will realize that it is a great scope for audio work, even with tube audio if you have a 10X or 100X probe...
As long as you realize it's limitations, and do not exceed them, it is a fabulous little scope for the price.
Have fun gaining more experience with using it...

[danielr.]

Warning ...do not touch metal parts such as connectors.

[SirWerner..]

Touch the bnc connector while measuring and you may be dead !!!

[diydsolar]

Hi, does the transformer disturb/smooth... the wave? I want to check modified and pure sine wave of inverters. Does it modify waves? What about armonics? Thanks a lot. May be you could test with two probes? One before and one after the transformer ?

[josepeixoto]

the little transformer introduces no new distorsion?
i wish you checked for that with a good scope

[kuronekosan]

How can i measure dc offset off from mini oscilloscopes like this ? I have the zeewei 154 pro