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Use of Oscilloscope Probe x100 Vs x1000
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2X:

--- Quote from: bdunham7 on April 06, 2024, 12:00:04 am ---
--- Quote from: 2X on April 05, 2024, 11:20:39 pm ---
Testec TT-HVP-40
https://www.batronix.com/shop/measurement/probes/Testec-TT-HVP-40.html

Testec TT-HVP-2739
https://www.batronix.com/shop/measurement/probes/Testec-TT-HVP-2739.html

--- End quote ---

The first is useless for you (it is only a low BW tool) and the second is massive (literally) overkill.  I would use my Tek P6015s for this, but I happen to have them--I wouldn't buy them for this occasion.

As far as recirculating or reactive currents, that's just basic AC circuit theory that you should get acquainted with.  When you put a capacitor across a sinusoid AC source, there is in fact a current and it is also a sinusoid, but it is out of phase by 90 degrees (leading the voltage) and therefore half of the time energy is being transferred to the capacitor and half them time it is being transferred from the capacitor, less any losses of course. If losses are low, there is very little energy actually lost in the process.  If your signal is not sinusoidal, things get more complicated but the same basic principles apply.

--- End quote ---

I didn't combine the 90 degrees out of phase with you wrote. Thanks for your reply. Also, I found and the below that you told me.

https://www.batronix.com/shop/measurement/probes/Testec-TT-HV-250.html

Phil1977:
That´s exactly the reason why I think you can get good results only with a differential probe.

With high voltage and high frequency, you have capacitors literally everywhere. If you use your probe without grounding, you have no idea about what your reference plane is doing - except you use two identical probes and do the differential math in the scope.

If you use probe grounding, you ether blow up your circuit or *massively* change the circuit by inducing a new low-z-connection where there is none in the original circuit. Galvanic isolation works only for DC or very low frequency AC, never for HF.

Please appologize if the first answer to your question was not very nice, but - without knowing special details - you just can not meassure with non-differential probes. And please don't think I didn't try to... :-X
Phil1977:
PS: A possible answer why x1000-probes exist: If you work a lot on HV-stuff you may also have unintentional discharges. A x100-probe transfers by design 10 times as much of the transient to the scope than a x1000-probe, so if the datasheet values are exceeded anyhow, then it´s of advantage to protect the scope instead of the probe.

Maybe there are also some instruments that just don't have a -/-50 V input range.

But as long as you use everything in spec, I can't see a good reason why the probe attenuation factor should make a great difference.
2X:

--- Quote from: Phil1977 on April 06, 2024, 07:47:28 am ---That´s exactly the reason why I think you can get good results only with a differential probe.

With high voltage and high frequency, you have capacitors literally everywhere. If you use your probe without grounding, you have no idea about what your reference plane is doing - except you use two identical probes and do the differential math in the scope.

If you use probe grounding, you ether blow up your circuit or *massively* change the circuit by inducing a new low-z-connection where there is none in the original circuit. Galvanic isolation works only for DC or very low frequency AC, never for HF.

Please appologize if the first answer to your question was not very nice, but - without knowing special details - you just can not meassure with non-differential probes. And please don't think I didn't try to... :-X

--- End quote ---

Thanks for you replies. I have made quite experiments with oscilloscope but fortunately I hadn't blow up something yet and because I know all the danger with the grounding I ask to many things here. In same cases the the groung was not so clear how is arranged on the PCB I have used two identical probes and I 've done the differential math in the oscilloscope but I had noise on the measured signal because the ground clips are not connectioned. I have used differential probe but I would like to risk and measure with "ordinary" probes. Always there is something to new even with risk.

I am close to select the two below for buying. They have good specs for what I want to experiment/measure.

Testec TT-HV-250
https://www.batronix.com/shop/measurement/probes/Testec-TT-HV-250.html

Testec TT-HVP-2739
https://www.batronix.com/shop/measurement/probes/Testec-TT-HVP-2739.html



tooki:

--- Quote from: 2X on April 05, 2024, 10:57:58 pm ---I have never used Testec probe or any other product of this brand... It has better, same or lower quality and safety from BK precision?

--- End quote ---
I have used many Testec probes and quite like them. Great quality at reasonable prices. The grips are a bit fatter than many probes, which I happen to like. I have some Testec at work and some at home.

Hameg (the test equipment company R&S purchased in order to break into the general test and measurement industry) shipped rebadged Testec with their scopes. (R&S now ships probes from another German manufacturer, PMK, which is more focused on high-bandwidth probes.)
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