Questions about multiple differential probing at the same time - Page 1
Forum section: electronics / testgear

author: nipil
author_rank: Contributor
timestamp: October 12, 2025, 09:54:08 am
content: HelloI am proficient with my DS1054Z and Micsig 10013 DP, and i have been diagnosing mains voltage for single and 3 phase motors with it, either with or without phase converters, or even inverters, or other installations up to "household voltages" (240V RMS) and building triac/thyristor based circuit for quite a time with this hardware.For various reasons, i would like to buy a second probe of the same type, and i have some questions :Q1)where have the cheap one gone ? I bought my MICSIG 10013 for 115€ in 2021, now they are 200€ up to 300€. In the previous price range i only found HT8050, and that may or may not introduce some problems (see question 3)Q2)(stupid question maybe) i never thought about it up to now as i plug my 10013 in the DSO usb : does the USB only provides power, or is there some data exchange with the DSO usb-host ? I ask because if i get a second DP with USB, i would like to be sure i could connect it to any wall-wart or power bank, or i know beforehand what features i would lose from not plugging it into the DSO usb port.Q3)do differential probes introduce any kind of delay in the probed waveforms ? i seem to remember (i might be wrong !) that when using the "AC trigger" of my DSO, the (direct) probing of mains voltage waveform was not really synchronized with the trigger time of the DSO display (i mean the zero crossing, which i expected to be the synchronization point). So if there is a delay introduced, how could i compensate for it ? Becasue if this delay varies with different probes, the compensation would be all the more "required" to compare both waveforms.Q4)the standard probes provided with the DSO are rated for 300V RMS. All the stuff i work with (excluding transients) are 240V RMS max. I have never encountered an issue (except maybe transient being clipped, but i do not remember...)a)i would like to know if the transients/spikes (ac motor starts, or inverters) are actually included or not in the ratings of any probes. And if higher transients happen, what does it do to the probe/DSO. I ask so i could safely use 2 more channels and use math difference to "compute" a "differential" signalb)but then i am wondering how these "non-differential" waveform would be synchronized (again, time-wise, see question 3) against waveforms acquired from "real" differential probes.Q5)i am oftern probing current using "out of circuit" current-transformer (anything like "naked" QNCTK1-16 or "voltage conversion" ZMCT103C boards and the likes). Do these current transformer introduce any delay in the waveforms ? The purpose of this question is the same as in question 3 and 4 : compensating for the eventual time delay to allow for proper waveform phase/triggering comparison.Thanks in advance for your time and insights,Nicolas

author: tautech
author_rank: Super Contributor
timestamp: October 12, 2025, 12:30:31 pm
content: Any2 different probes will give different signal propagation delays resulting in channel skew.Channel skew can be nulled in the probe menu and for voltage probes the fast rising edge of the probe compensation output is sufficient for low frequency skew adjustments.Some suppliers offer specialized PCB's to provide current and voltage pulses for nulling the channel skew common in current probes.https://siglentna.com/product/power-analysis-deskew-fixture/

author: danno_cj
author_rank: Contributor
timestamp: October 12, 2025, 05:18:15 pm
content: Q1The explanations about this: the life in general has become harder, everything is more expensive today and the probe are not exactly the same. The new version DP1500 which replace the model that you have has got better. The new one has real and higher CMRR numbers.Q2USB is just to provide power to probe, no communicationQ4The voltages on these differential probe are PK to PK. There is some reserve space, probably around 200-300V. If you reach the limit + reserve the values on scope are clipped. No damage to scope or probe except you are pushing limits way to much.Q4aUsing 2 channels and use math difference to "compute" a "differential" signal works but CMRR will be bad.Micsig probes are the cheapest quality differential probe. Cheaper are Hantek and Loto but these don't have same performance especially regarding noise. You may regret buying these but if you want to try come back here with feedback.

author: nipil
author_rank: Contributor
timestamp: October 12, 2025, 07:56:14 pm
content: Quote from: danno_cj on October 12, 2025, 05:18:15 pmAs a hobbyist, i regret the price gap but i do not have high precision requirements which would warrant the investment for "the good stuff"...I indeed did not realize that the old one i have indeed been phased-out (and replaced !) : thanks for pointing it out.Quote from: danno_cj on October 12, 2025, 05:18:15 pmTo make sure i do not misunderstand, can you confirm that the "reserve" you talk about :- only applies to the differential probes ?- or applies to standard probes too ?That is to make sure that,when using 2 standard probes and "math difference", the scope and I are still safe during transients (up to a certain point of course, and with bad CMRR as you said)Quote from: tautech on October 12, 2025, 12:30:31 pmIs it a constant time or does it depend on the measured signal frequencies ?If constant, i guess i can i simply measure it once (for example with a resistive load on mains, and AC trigger) then write it down and then compensate in the menus each time i use the probe ?

author: danno_cj
author_rank: Contributor
timestamp: October 12, 2025, 09:09:41 pm
content: Only applies to the differential probes!Dave tested 10007 up to 1100V RMS and wasn't broken. Until 575V RMS was fine, after 580V RMS clipped.https://youtu.be/V93Rnco-wKg?si=U1aNg4Mu14O5ikS5

author: tautech
author_rank: Super Contributor
timestamp: October 13, 2025, 08:01:51 am
content: Quote from: nipil on October 12, 2025, 07:56:14 pmSkew can be ns or just ps depending on the probe.Some specialist probes have a very long coax, up to 1.5m so along with the particular probe propagation delay you also have coax length delays to consider.Much depends on your needs for absolute probe skew accuracy where in some modern DSO's Power Analysis computation accuracy is highly dependant on accurate probe deskewing.