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Accurate Low Amp Current Probe Advice
Kean:
--- Quote from: Phil1977 on October 29, 2024, 08:42:01 am ---Just to show how bad it can be with cheap equipment:
--- End quote ---
FYI, there are some potential improvements you can try
https://www.eevblog.com/forum/testgear/peaktech-4250-acdc-current-clamp-teardown-and-repair/
Not sure if they will help with low current measurements.
nctnico:
--- Quote from: Kean on October 29, 2024, 10:50:55 am ---
--- Quote from: Phil1977 on October 29, 2024, 08:42:01 am ---Just to show how bad it can be with cheap equipment:
--- End quote ---
FYI, there are some potential improvements you can try
https://www.eevblog.com/forum/testgear/peaktech-4250-acdc-current-clamp-teardown-and-repair/
Not sure if they will help with low current measurements.
--- End quote ---
I don't think so. With a range of 60A, the noise is just too much to measure in single digit mA range. However, I think the lower range clamp which KungFuJosh has tested a few posts up, has the ability to measure currents in the mA range. Only nulling it precisely will be tricky and noise will need to be filtered / averaged.
Martin72:
--- Quote from: Phil1977 on October 29, 2024, 08:42:01 am ---Maybe I can try the same test with the Micsig CP2100B end of the week, but last time I compared them against each other there was not a huge difference.
--- End quote ---
I had once opened a thread about a Micsig CP2100, with various tests:
https://www.eevblog.com/forum/testgear/micsig-current-probe-cp2100b-tests-and-comparing/msg3070834/#msg3070834
(and the following pages)
DaneLaw:
Tried with the Hantek CC65 (also 60A rated clamp) to see if it could muster minute current clamp values.
The setup is as crude as it gets..
Top of a washing machine, no shielding..
Sig gen DG800PRO 50Hz sine, sq w. with a cheap BNC cable to alligator fitted with 10R metal film resistor.
1mA pr div. (as low as the scope will go) with lpfiltering & avg.
The noise from the clamp can be cleaned up quite a bit on these Micsig scopes with both variable bandwidth filtering and averaging, so even minute mA, triggered..
Setup.
Sensorcat:
--- Quote from: DaneLaw on October 30, 2024, 07:35:00 am ---Tried with the Hantek CC65 (also 60A rated clamp) to see if it could muster minute current clamp values.
--- End quote ---
Could you please explain your setup in more detail (the video is a bit blurred)? I'm a bit puzzled trying to get the numbers together: The Hantek has, in its more sensitive range, 1 mV / 10mA, which is equivalent to 100µV / 1mA. I checked the Micsig range at Batronix and could not find a model with a sensitivity higher than 1mV/DIV. The 2nd screenshot tells 1.52mA PK-PK and the trace covers about 1.5DIVs. Doesn't that require a 100µV/DIV range? OTOH, the AWG seems to read 700mV, and, if I understand correctly, you used a 10Ω resistor as load? With 50Ω output impedance, this would lead to 700mV/60Ω = 11.67mA. Should this be the actual current, the resolution of the measurement would still be impressive, especially because of the stable triggering, since the cleanup through averaging cannot happen without stable triggering on the single acquisition to average. So please tell something on the variable filtering your instrument has!
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