3 ms·

> This can be done safely with high voltage differential probes like the R&SRT-ZHD, but we don't have any. Entry level differential probes are $300. Less if yo

> This can be done safely with high voltage differential probes like the R&SRT-ZHD, but we don't have any. Entry level differential probes are $300. Less if you shop around or buy used. Micsig makes a good starter probe that would be more than enough for 60Hz AC mains testing and it comes in a generic form that would have worked with this scope. A lot of things can go wrong, some dangerously so, if you incorrectly probe high voltage lines. I don't know why they got such an expensive oscilloscope and then proceed to cheap out on the most basic tools needed to use it properly.

SigmundA 6mo ago
Why are differential probes so expensive and why don't more scopes just have differential port built in? For about $300 you can buy a Tiepie differential usb scope: https://www.tiepie.com/en/usb-oscilloscope/handyprobe-hp3 https://www.tiepie.com/en/usb-oscilloscope/handyprobe-hp3
- Aurornis 6mo ago
  You can create a pseudo-differential input by combining two input channels on almost every scope. That's not the problem the differential probe is solving, though. The differential probe exists to provide a differential measurement between two voltages that may be isolated or significantly different than the ground voltage of your oscilloscope. The ground lead on your probes is connected straight to the ground on the power cable. This gets new users in trouble when they're probing power circuits and they don't realize that connecting the ground part of the probe to something will cause a short to ground. If that ground clip pops off and brushes against the high voltage you're trying to probe, you get sparks and maybe a destroyed scope. The differential probe provides isolation and rejects the common-mode (shared) voltage between the two probe points before it gets to the oscilloscope. I don't know about that USB probe, but I prefer not to have single-purpose instruments that require their own desktop software to use.
  - SigmundA 6mo ago
    I understand what a differential probe does, what I don't understand is why they are so expensive. Again one can get a whole USB differential scope for the same price or less. Seems like just a differential probe should be relatively inexpensive well under a $100. The Tiepie software actually works very well even though it's Windows only, they do have Linux library, just no GUI on Linux. Its not single purpose its a full oscilloscope that happens to use differential inputs. They actually do sell one more purpose built for power quality analysis which is new. I would love to have a couple on my home power split phases to view and log power quality in detail: https://www.tiepie.com/en/usb-oscilloscope/handyscope-tp450 https://www.tiepie.com/en/usb-oscilloscope/handyscope-tp450
    - Aurornis 6mo ago
      A good differential probe has to use precision components combined with careful factory trimming and calibration to get good common mode rejection ratio. The CMRR of the Micsig I linked is pretty average, but it's a lot better than the TiePie at low frequencies. Micsig also specifies it at multiple points across the spectrum, while TiePie doesn't even say where they measured it. It's all the differences like this that make good test gear expensive. The Micsig is not expensive on the scale of these devices. The professional gear will have even better specs, calibration, long-term stability, temperature stability, and many more features. For playing around, the TiePie thing will do fine.
      - SigmundA 6mo ago
        >The CMRR of the Micsig I linked is pretty average, but it's a lot better than the TiePie at low frequencies. Micsig also specifies it at multiple points across the spectrum, while TiePie doesn't even say where they measured it. It worse at high frequencies and the same in the middle. Again this is a whole scope compared to a probe. Not sure why you think Tiepies are toys, they are use professionally in Europe, popular for automotive. They have a lot more expensive scopes, and the price difference for the differential versions are not that much.
    - labcomputer 6mo ago

SigmundA 6mo ago

Why are differential probes so expensive and why don't more scopes just have differential port built in? For about $300 you can buy a Tiepie differential usb scope: https://www.tiepie.com/en/usb-oscilloscope/handyprobe-hp3 https://www.tiepie.com/en/usb-oscilloscope/handyprobe-hp3

Aurornis 6mo ago
You can create a pseudo-differential input by combining two input channels on almost every scope. That's not the problem the differential probe is solving, though. The differential probe exists to provide a differential measurement between two voltages that may be isolated or significantly different than the ground voltage of your oscilloscope. The ground lead on your probes is connected straight to the ground on the power cable. This gets new users in trouble when they're probing power circuits and they don't realize that connecting the ground part of the probe to something will cause a short to ground. If that ground clip pops off and brushes against the high voltage you're trying to probe, you get sparks and maybe a destroyed scope. The differential probe provides isolation and rejects the common-mode (shared) voltage between the two probe points before it gets to the oscilloscope. I don't know about that USB probe, but I prefer not to have single-purpose instruments that require their own desktop software to use.
- SigmundA 6mo ago
  I understand what a differential probe does, what I don't understand is why they are so expensive. Again one can get a whole USB differential scope for the same price or less. Seems like just a differential probe should be relatively inexpensive well under a $100. The Tiepie software actually works very well even though it's Windows only, they do have Linux library, just no GUI on Linux. Its not single purpose its a full oscilloscope that happens to use differential inputs. They actually do sell one more purpose built for power quality analysis which is new. I would love to have a couple on my home power split phases to view and log power quality in detail: https://www.tiepie.com/en/usb-oscilloscope/handyscope-tp450 https://www.tiepie.com/en/usb-oscilloscope/handyscope-tp450
  - Aurornis 6mo ago
    A good differential probe has to use precision components combined with careful factory trimming and calibration to get good common mode rejection ratio. The CMRR of the Micsig I linked is pretty average, but it's a lot better than the TiePie at low frequencies. Micsig also specifies it at multiple points across the spectrum, while TiePie doesn't even say where they measured it. It's all the differences like this that make good test gear expensive. The Micsig is not expensive on the scale of these devices. The professional gear will have even better specs, calibration, long-term stability, temperature stability, and many more features. For playing around, the TiePie thing will do fine.
    - SigmundA 6mo ago
      >The CMRR of the Micsig I linked is pretty average, but it's a lot better than the TiePie at low frequencies. Micsig also specifies it at multiple points across the spectrum, while TiePie doesn't even say where they measured it. It worse at high frequencies and the same in the middle. Again this is a whole scope compared to a probe. Not sure why you think Tiepies are toys, they are use professionally in Europe, popular for automotive. They have a lot more expensive scopes, and the price difference for the differential versions are not that much.
  - labcomputer 6mo ago