On Sun, 20 May 2018 10:40:54 -0700, you wrote:
Harvey, thanks for your example. I do somewhat the same with a voltmeter in respect to measuring voltage drop/gain rather than doing the math, I can get higher resolution too since the decimal moves over.
Your high voltage idea in respect to exceeding limits; would it be possible to use the 2 channels to measure a floating high voltage that exceeds the single channel to scope chassis limit of say, 500V peak? Given a 1M channel impedance, do I end up with a 2M impedance? Could this be a method to cut scope loading on the DUT in half?
I am not happy with that use. Say you have 800 volts, you'd need to
find a 400 volt supply to "float" the scope, and measure the lower and
upper end with the scope probes. While you may not exceed the input
voltage maximum, the thought of a scope chassis somehow floating at
400 volts above ground, (OR your UUT having that kind of voltage
extent somewhere (as in scope chassis is 400 volts, UUT chassis is
-400 volts) is not a pleasant thought.
Again, a battery operated scope (double insulated) *might* be able to
do this, and likely would within the limits of (whatever voltage) per
channel. That would be the only use that I'd even consider, and I'd
go find the high voltage probes that are made to handle this kind of
situation.
In theory, you would get a 2 meg impedance, but even on a low voltage
circuit, I just have a feeling that this is a bad idea, measurement
wise.
Best practice and safest practice is to avoid putting the equipment in
this kind of situation.
Overall, my immediate feeling is "don't do this".
Harvey
And yes, this is an academic question, the examples help me to understand the testing possibilities with my scope.
NielsenTelecom
