| The thing you posted isn't the same thing as a differential probe. It's a single input low bandwidth scope that floats at the common mode voltage, with an optically-isolated data output. Now, let's say you want to probe two things at the same time (triggered by a common signal source). You can't. And the reason you can't is because the producer took the expedient of floating the entire scope, and there's no trigger input. In other words, they took the cheap way out by not actually building a differential probe. Related to that, this thing doesn't appear to have a step attenuator, which is why the effective resolution depends on the volts/div setting of the input. Also, they don't specify the CMRR, which is one the main figures of merit people look for on differential probes. Any capacitive coupling between the scope and ground is going to degrade CMRR. So who knows if it can actually measure anything useful. You can buy a scope with multiple optically-isolated channels as well as a trigger input, but those end up costing as much as a differential probe. Because it turns out that achieving good CMRR when you have multiple inputs is as hard a problem as making a good differential probe. This is not to say the product you linked shouldn't or can't be used for anything, but it is a niche product. That's probably why it is advertised as a "power quality monitor" and not an "oscilloscope". |
Yes this is very inexpensive single input scope, they make more expensive multi input scopes you can stack as many as you want and have them synced:
https://www.tiepie.com/en/usb-oscilloscope/handyscope-hs6-di...
The difference in price between their single ended and differential scope is not the much so it seems the actual differential part is not the expensive part, back to my original point.
>Related to that, this thing doesn't appear to have a step attenuator, which is why the effective resolution depends on the volts/div setting of the input.
They sell differential step attenuators: https://www.tiepie.com/en/usb-oscilloscope/accessories/diffe...
>Also, they don't specify the CMRR, which is one the main figures of merit people look for on differential probes.
CMMR 60db from thier spec sheet: https://download.tiepie.com/Documents/Datasheets/Datasheet-H...
>This is not to say the product you linked shouldn't or can't be used for anything, but it is a niche product. That's probably why it is advertised as a "power quality monitor" and not an "oscilloscope".
From their spec page: "The tables below show detailed specifications of the Handyscope TP450 high voltage oscilloscope."
and
"The Handyscope TP450 is delivered with the versatile Multi Channel oscilloscope software, which transforms the Handyscope TP450 into an oscilloscope, spectrum analyzer, data logger, multimeter and protocol analyzer."
They make quite a few differential scopes, that just happens to be a inexpensive one physically deigned for power quality analysis.