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Micsig CP1003/CP503 100MHz/50MHz Current Probe

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Fred_47:

--- Quote from: EEVblog on November 19, 2022, 02:55:17 am ---No, this is the opposite. Not multiple turns to turn a large current proce into a smaller current probe, but a single thicker wire paralleled with a thinner wire that goes through the current probe to turn a small current probe into a bigger current probe. Probaby easier to use say 10 wires of the same diameter and then only clamp one of them, bingo 1:10 probe.

--- End quote ---

There will be a small additional voltage drop in the wire thru the core because of the probe, that doesn't occur in the bypass conductors. Whether it is large enough to matter is a subject for experimentation.

Martin72:

--- Quote from: jonpaul on January 25, 2023, 11:52:53 am ---For 600..1200 EU you can get a very fine TEK vintage probe with amp.

Check epay for Tektronix current probes

Jon

--- End quote ---

Yes and I also have one because is still unbeaten in terms of performance, apart from the very expensive current probes from hioki, which run under different names.(which are equal, not "better")
(R&S, Lecroy, Rigol and Siglent...no kidding).

Siglent probe

Rigol probe

R&S probe

Lecroy probe

And that's the problem, the old Tek system is great but very space consuming, the nice narrow probes from Siglent and co. way too expensive.
And so I've been waiting for a good and yet inexpensive probe from China....
To date, all I had up to 600 € were nothing.
From this point of view, the 1200€ would be a bargain, the Micsig would bring a very similar performance.
But you do not know currently and even if it would be "only" 1200, I do not want to play a test rabbit this time. ;)
Plus I really do not understand why the universal "B" variant costs twice as much as the one for micsig scopes only.  :o

PartialDischarge:
One problem with clamp probes is that CMRR is either not specified or is very bad. Historically CMRR was not a very demanded spec in current probes so the trend of not asking for it has continued.
So for high side/floating current measurements, there is going to be a nice distortion.

EEVblog:

--- Quote from: Martin72 on January 25, 2023, 06:13:03 pm ---Plus I really do not understand why the universal "B" variant costs twice as much as the one for micsig scopes only.  :o
--- End quote ---

It shouldn't from what I've been quoted wholesale pricing for the B varient.

jonpaul:
Rebonjour, cher PartialDischarge ...

" clamp probes ...CMRR  not specified or is very bad.
 for high side/floating current measurements, there is going to be a nice distortion"

Well there is not a "high sided distortion" but a predictable CM noise coupling proportional to  Dv/Dt of the circuit probed and the stray C probed wire to probe body.

Thus CM current = Icm = C dV/Dt

In 55 yrs we never had a problem with a current probe CMRR.

No spec as the coupling depends on conductor size and position in probe jaw aperture.

  Cp-s is perhaps a few pF.

 But any CMRR issue  is easy to solve.

1. Place probe at rtn/low side of circuit not at high side, eg BJT NPN emitter or FET drain.

Thus the CM  voltage is minimum, near ground.

2. Make a small copper shield around the conductor, with a slit to avoid shorted turn/

Wrap the shield tightly around the conductor. No shorted turn!

Ground the shield: Voila a Faraday shield.

Jon

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