Looking at slide #3 of the 5th lecture, I'm reminded of the concerns you might have measuring a high-side shunt in a high voltage/high power circuit.
If you're measuring with a scope or data logger, you need to use 2 single-ended channels, one on each side of the shunt, because a scope or data logger normally have a grounded (earthed) chassis. If you try connecting the ground clip of a single-ended scope channel to the low side of a shunt, you could destroy the instrument due to high currents flowing from the UUT through the instrument's chassis to earth.
If the instrument's channels are differential or if you have a differential probe, then you can measure the voltage across a shunt with one channel of the instrument.
Floating a scope or data logger's power source is a bad idea if you're attmempting to make a high side shunt measurement with a single channel because the instrument's chassis could be at a high and dangerous voltage with respect to earth. One brush against the instrument and you get a potentially lethal shock.
rswanson: using an op amp to square an analog signal is fairly easy--check app notes from any major analog vendor, it's a classic circuit configuration. I know some early but still valid app notes from ADI show how to do it.
To all: remember, when you talk with an experienced vendor, they will raise issues you may not have even thought you needed to be worried about--but hey, it's worth listening to what they say, even if it may not be a concern of yours in the end, in your situation.
rswanson: by analog, I meant a basic op amp scaled to transform the input signal x the resistor size--you don;t really need to do a true multiplication of two unknown analog signals. And I think vendor like Microchip do make power-measurement ICs which combine analog and digital blocks in one easy-to-apply device.
The first Tacoma Narrows Bridge was a Washington State suspension bridge that opened in 1940 and spanned the Tacoma Narrows strait of Puget Sound between Tacoma and the Kitsap Peninsula. It opened to traffic on July 1, 1940, and dramatically collapsed into Puget Sound on November 7, just four months after it opened.
Noting that we now live in an era of “confusion and ill-conceived stuff,” Ammunition design studio founder Robert Brunner, speaking at Gigaom Roadmap, said that by adding connectivity to everything and its mother, we aren't necessarily doing ourselves any favors, with many ‘things’ just fine in their unconnected state.
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