On Fri, 15 Feb 2019 19:02:44 -0800, Jeff Liebermann
wrote:

On Fri, 15 Feb 2019 15:33:01 -0800, wrote:

Below is an answer I gave to Mike about the wave shape and other
features. The description should give you a better idea of what I am
seeing. At least I hope it does.

"Whoops! It looks like the wave is over compensated. So it looks like
at the beginning of the flat waveform it has a little peak that then
drops down to form a flat line for the rest of the wave.

Under compensated or too little capacitance. The overshoot of the
rising part of the square wave means you have too much high frequency
response.

This of
course repeats but in the negative direction for the negative part of
the wave.

Yep. If the negative going part of the waveform were not identical,
then your input square is not symmetrical.

I thought you meant frequency for the time dimension but now
I think what you mean is how long does it take for the waveform to
become flat.

No. The flat part of the waveform is the low frequency component,
which is independent of the rise time. If the flat part sags, then
you are capacitor coupling (AC coupling) somewhere, probably the AC/DC
switch on the vertical input.

It looks like it takes .1 mS. And the overshoot is about
30mV

I can't tell if that means that it sags 0.1msec or the overshoot lasts
0.1msec. Perhaps a posting photo of the screen would be helpful.

More reading:
"The Secret World of Oscilloscope Probes"
http://www.dfad.com.au/links/THE%20SECRET%20WORLD%20OF%20PROBES%20OCt09.pdf

The link in the video to EEVblog doesn't work. This does:
"EEVblog #453 - Mysteries of x1 Oscilloscope Probes Revealed"
http://www.eevblog.com/forum/blog/eevblog-453-mysteries-of-x1-oscilloscope-probes-revealed/?all
Thanks again Jeff. I have watched EEVblog several times and haven't
had time yet to check out completely the episode mentioned. I looked
for it and just got it started when the dryer belt broke. Anyway, when
I spoke above about .1mS I meant that the overshoot lasts that long.
So there is a peak at the beginning of the square wave and then the
trace curves down to become flat. And the time it takes to become flat
is about .1 mS. The computer I am posting from is running XP and so I
can't use Dropbox. I should look for another easy to post to picture
site.
Eric