Using the ground lead on the LeCroy LC584AXL....
Using the ground lead on the LeCroy LC584AXL....
(OP)
I am trying to measure the voltage across a series resistor (in the power leg of my supply circuit?, and would like to use only 1 scope probe. Is there any easy way to do this without floating the scope? I really don't want to take 2 absolute readings and perform math (can't trigger on math function, and resolution is limited).
Thanks,
Thanks,
RE: Using the ground lead on the LeCroy LC584AXL....
You could breadboard a unity-gain diff amp and glue it to your probe and power it with a couple of 9V batteries.
TTFN
RE: Using the ground lead on the LeCroy LC584AXL....
If AC, a current transformer might suffice, but ‘scope floating can be a bit Darwinian. Burr-Brown isolation amplifier?
RE: Using the ground lead on the LeCroy LC584AXL....
RE: Using the ground lead on the LeCroy LC584AXL....
Steve Owens
Finish Line Product Development Services
Steve.Owens@FinishLinePDS.com
www.FinishLinePDS.com
RE: Using the ground lead on the LeCroy LC584AXL....
RE: Using the ground lead on the LeCroy LC584AXL....
RE: Using the ground lead on the LeCroy LC584AXL....
RE: Using the ground lead on the LeCroy LC584AXL....
Here is something that might help you. I came across it yesterday while looking for something else. - Electronic Design, Ideas for Design, Aug. 19, 2002, page 62. Titled: "High Voltage Monitor Features High Accuracy". It will give better than 20ppm accuracy up to 400Volts. The article can be downloaded in .pdf format.
The only other option is a differential probe, but then you have to decide what to do with the ground terminal on it.
RE: Using the ground lead on the LeCroy LC584AXL....
Thanks for the help!
RE: Using the ground lead on the LeCroy LC584AXL....
melone—just for giggles—what is the voltage to ground on the series resistor of interest?
RE: Using the ground lead on the LeCroy LC584AXL....
RE: Using the ground lead on the LeCroy LC584AXL....
Apparently, there are no imminent safety concerns.
Accessories like http://home.europa.com/~oatpmk/ampintro.htm or http://www.linkinstruments.com/adf25.htm are probably out of budget.
RE: Using the ground lead on the LeCroy LC584AXL....
How did you float your scope? Was it with an isolation transformer? I ask since you say floating your scope didn't work. I can't think of any reason that would not have worked.
RE: Using the ground lead on the LeCroy LC584AXL....
RE: Using the ground lead on the LeCroy LC584AXL....
<nbucska@pcperipherals.com>
RE: Using the ground lead on the LeCroy LC584AXL....
RE: Using the ground lead on the LeCroy LC584AXL....
<nbucska@pcperipherals.com>
RE: Using the ground lead on the LeCroy LC584AXL....
The result is, that you can end up with a difference in potential between the ground of the scope and the ground of your circuit and may possibly induce very LARGE ground currents into the input amplifier of your scope.
My friend was trying to do something similar to you. He circuit had about 12 volts across the current sense resistor. The Tektronix repair person estimated that something like 100 Amps was dumped into the vertical amplifier input. It melted a lot of stuff.