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| Looking for portable oscilloscope |
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| csuhi17:
--- Quote from: abgx1 on December 11, 2023, 04:33:55 pm ---Well, at some point, the amperage of the fuse doesn't matter anymore because it just won't trip, no matter how hard you're trying. 🙂 The frequency inverters I commonly come across are in the range of 0.18-11 kW, which means around 25-26A at max. Anyway, I did some studying, and I see four options: 1. Buying differential probes - That's too expensive, at least for now. 2. Buying a scope with isolated inputs - That's even more expensive. 3. Using a grounding connector with a big green/yellow wire connected to the 100% safe grounding point (for example, a lightning rod on those wells) as a reference point so I do not have to use the probe grounding lead at all - That sounds pretty safe to me. 4. Could I use the second channel as a reference point? I mean, I would connect channel 1 through a 1:100 probe on mains voltage. Then I would connect channel 2 through a 1:100 probe to the ground. Finally, I would subtract channel 2 from channel 1. Now, when I see it written, I think that option 4 is impossible since I will not be able to measure any voltage on channel 1 without grounding. Is that true? Currently, I am leaning toward the Rigol DHO804 and option (if option 4 is not possible), if you guys do not have a better idea that does not cost a four-figure price. I have excluded Owon from selection since it doesn't have a grounding point other than one on the probe.. --- End quote --- If I wrote something wrong or ambiguous, please correct me, unfortunately English is not my first language. If it is enough for you to just see the signal and not perform any serious measurements on it, and the display size is fine for you: Differential measuring head: Hantek HT8050 for about 180 Euros or Micsig for about 250 EurosBangood sell it cheaper 150USD. Small handheld scope HDS242 around 140 Euros. The 40Mhz configuration comes out to around 320 Euros. You wrote that ~16 kHz should be around. If you need a more serious one, the oscilloscope is at least the Rigol DHO804 or maybe the others can recommend a cheap portable version. Forget Fnirsi and company. Maybe the DPOX180H, but only if you can get it cheap. it is worth putting a cap on each channel, and covering the measuring points of the 1kHz test signal with some sort of insulator. If I understand correctly what you wrote in point 4. You will not be able to use the two channels in such a way that the "Ground" wire of both channels is not connected anywhere. and You connect the "signal" wire of the first channel to the main voltage and the "signal" wire of the second channel to ground. This is wrong in principle, since the "Ground" reference point of both channels is "floating?" Did you read about the differential probe when you came up with this? Do any of fluke's handheld oscilloscopes have a separate ground?! Even the Fluke 190 Series III ScopeMeter doesn't include it, that is, I can't see it anywhere, even though it's a +4000 Euro instrument. As written above, compliance with the safety regulations is the most important. |
| abgx1:
cushi, you understand point 4 correctly. I wasn't reading about a differential probe, it was just a random idea that I got. But now I understand that it is not possible to measure completely without ground when not using differential probe. So I will stick with option 3 + Rigol 804 and maybe later I will buy some differential probe... |
| csuhi17:
ok When I measure higher voltages, I always use one of the battery scopes, floating. I don't know how to measure with a grounded oscilloscope! check properly how to do it, so that there is no problem. |
| shapirus:
--- Quote from: shapirus on December 11, 2023, 04:41:37 pm ---Practical implementation is a different story. I can't confirm that it works, but something tells me that it should be viable. --- End quote --- 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. |
| smaultre:
I'm just trying the same trick ch.A - ch.B with Fluke. I't works fine, math is GREEN line. |
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