Interpreting an oscilloscope waveform

Thread Starter

kminnich

Joined May 19, 2017
2
Hi, I am just learning about electronics in general so I can have a better understanding of how things work. I built a cheap, pocket oscilloscope (DSO-068) from China and have been trying to get the hang of how to use it. This . .is a screen shot of a 6.9 VAC waveform that I captured with it.6-9VAC Wave.jpg
The items marked in red on the image are my interpretation of the display for the 6.9VAC input signal.
I have two questions: (1) am I interpreting the screen correctly and (2) Why is the display voltage > 10VAC and -10VAC when the input is 6.9VAC?
Note: Since the display only has six vertical divisions, I am using a 10X probe.

I realize that this is not the best of scopes but I think it will suit my needs for learning simple circuits.
 

crutschow

Joined Mar 14, 2008
34,019
The vertical scale on an oscilloscope is just volts (V) not VAC, since it can respond to either an AC and/or a DC signal depending upon the input coupling setting.

ms is milliseconds, us or μs would be microseconds.
 

Thread Starter

kminnich

Joined May 19, 2017
2
Thanks to all that responded. I was unaware of the RMS factor so now when I look at a sine wave I will know how to derive the value from it(nsas & #12). I also learned that a DSO plots VOLTS not VAC/VDC(crutschow) which makes a lot of sense and as a bonus drc_567 showed me how to compute the frequency from the plot! I am assuming that my interpretation of the display was accurate (except for the VAC labels) and that the DSO produces fairly accurate results.

Thanks again -- I'll be back!
 
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