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Looking for portable oscilloscope

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abgx1:
What is the cheapes differential probe which can be used on main voltage?

nctnico:

--- Quote from: abgx1 on December 12, 2023, 01:50:57 pm ---What is the cheapes differential probe which can be used on main voltage?

--- End quote ---
Last time I checked the CAT rated ones from Micsig are the most economic ones.

shapirus:
I believe there also were some feasible DIY designs discussed on this forum (that someone actually implemented). Search should show them.

Fungus:

--- Quote from: abgx1 on December 12, 2023, 01:50:57 pm ---What is the cheapes differential probe which can be used on main voltage?

--- End quote ---

Micsig.

alm:

--- Quote from: shapirus on December 11, 2023, 09:09:20 pm ---So it doesn't work. I have just verified this with a handheld battery-powered scope: when the ground clips are detached, the Ch1-Ch2 (math) waveform becomes garbage.

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The signals need to stay within range for both channels. Especially with a floating scope the reference level may well be at a level away from ground, pulling the signals relative to the reference out of range. With a grounded scope this is not going happen because CH1 and CH2 are always referenced to ground. This is also a potential problem with real differential probes. Which is for example why Fluke tells you to ground the floating scope when using two differential probes at the same time.


--- Quote from: nctnico on December 12, 2023, 12:22:07 pm ---For measuring high voltages / mains safely, you'd need a CAT rated differential probe though.

--- End quote ---
No, you don't need a differential probe. A single-ended probe designed for floating measurements will also work. It's not like the reference level is moving much relative to earth. If you read the manual for high voltage differential probes, they have statements like "make sure the oscilloscope is grounded" or "These probes are designed for use with oscilloscopes that have a common terminal at GROUND POTENTIAL". So I'd say a single-ended probe for floating measurements is a better choice for a battery-powered scope with isolated inputs (the only type of battery-powered scope I'd use on mains). Either that, or use a grounded scope with a high voltage differential scope.

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