Author Topic: Micsig CP1003/CP503 100MHz/50MHz Current Probe  (Read 57681 times)

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Offline Dennis Frie

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #150 on: September 19, 2024, 07:36:19 pm »
I was debating whether to buy the Siglent CP6030 or the Micsig CP503B current probe. Considering the price-tag of the Micsig CP503B probe, I decided it was still an interesting probe, even with the linearity issues.
I have to say, so far the noise and DC accuracy is pretty damn good.

I've played around a bit with the frequency response, trying to measure it at slightly higher currents. Still pretty bad compared to the specs as shown previously in this thread, but overall not a bad current probe the price considered. Compared to the 100 MHz model tested earlier in this thread, I see no reason to buy the 100 MHz as the linearity problems seems comparable.
I will probably stick to the Lecroy CP030 probes for high-frequency stuff, but a great probe for a lot of other things.
 

Offline Dennis Frie

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #151 on: September 19, 2024, 07:49:20 pm »
Direct comparison of the measurement Martin72 did.
Same scaling on the y-axis, but tested with higher current. Considering I get significantly better linearity with a 50 Mhz probe, I either got lucky with the probe or the higher current makes a difference.

Yellow = Martin72' original test
Green = my trace copied into the image

Tested with 5 Vpp, 25R load (50R external + 50R internal in scope) and 3 turns on current probe. Gives approx. 400 mApp @ 1 kHz
« Last Edit: September 19, 2024, 07:56:05 pm by Dennis Frie »
 
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Offline Martin72

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #152 on: September 19, 2024, 09:23:13 pm »
Hi,
That looks better, but if this behavior only occurs at higher currents, it's still not for me.
Apart from that, I'm disappointed with Micsig's support; they never got back to me.
No, I'll wait until I can afford the Siglent Current probe:
https://www.eevblog.com/forum/testgear/siglent-cp6030-current-probe-a-very-very-short-review/msg5352083/#msg5352083

Until then, I'm doing fine with my Tektronix A6302...

Offline Dennis Frie

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #153 on: September 20, 2024, 11:07:47 am »
Hi,
That looks better, but if this behavior only occurs at higher currents, it's still not for me.
Apart from that, I'm disappointed with Micsig's support; they never got back to me.
No, I'll wait until I can afford the Siglent Current probe:
https://www.eevblog.com/forum/testgear/siglent-cp6030-current-probe-a-very-very-short-review/msg5352083/#msg5352083

Until then, I'm doing fine with my Tektronix A6302...

Yeah I did consider the Siglent CP6030 after reading your tests. No doubt it's a better probe, but it also comes at a significantly higher price.
I think the Micsig probe has its place, but the datasheet specs and graphs are misleading.
 
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Offline folays

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #154 on: October 25, 2024, 03:10:55 pm »
Hi, I've bought a brand new CP503B, is having only XX mA precision on a constant DC 30V / 2A normal ?
Here below are the probe in the 6A range (correctly in the lock position !) when power supply is OFF, then ON.
As you will see, under 2A of current, the probe measures an AMPLITUDE of 237 mA (24 mA at rest).
Should I send back my probe ? I've bought it at Jeulin because 2 days ago Batronix didn't have it in stock, maybe I should have asked and waited...

The Datasheets ( https://www.eevblog.com/forum/testgear/micsig-cp1003cp503-100mhz50mhz-current-probe/msg5260149/#msg5260149 ) says :
Code: [Select]
DC accuracy : ±1%±10mA (6A)
2413691-02413695-1
(for info, under the 30A range, the "imprecision" (Amplitude) would jump from 237 mA to around 440 mA.

Previous forum user here https://www.eevblog.com/forum/testgear/micsig-cp1003cp503-100mhz50mhz-current-probe/msg5259840/#msg5259840
shows it had (albeit at a much reduced voltage, possibly from an AC source) a Pk-Pk of 10 mA, whereas even under NO LOAD I still have much worse Pk-Pk of 24 mA.

Here below is the setup of the lab power supply + the DC electronic load (which I put on a constant RESISTANCE).
Maybe I misunderstood the ability of the DC load to really maintain a stable resistance (or current) under a stable power source ?
2413699-2

For the sake of checking with a constant CURRENT setting on the DC load (no photo included, but I set the DC load on CC 2A "in the 5A and 36V range") :
2413703-3
Much better, 175 mA of Amplitude, but it seems way off the Datasheet precision (±1%±10mA) which should have yield a measured amplitude precision of 30 mA max ?

Thanks & Best Regards,
 

Offline Martin72

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #155 on: October 25, 2024, 03:42:25 pm »
Hi,

https://www.eevblog.com/forum/testgear/micsig-cp1003cp503-100mhz50mhz-current-probe/msg5275105/#msg5275105

See the noise picture, try to recreate it with the settings you can see in the picture.
Then:
You're not triggering on channel 4, I'd change that if I were you.

Offline Kean

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #156 on: October 25, 2024, 03:57:43 pm »
Hi, I've bought a brand new CP503B, is having only XX mA precision on a constant DC 30V / 2A normal ?
Here below are the probe in the 6A range (correctly in the lock position !) when power supply is OFF, then ON.
As you will see, under 2A of current, the probe measures an AMPLITUDE of 237 mA (24 mA at rest).

Do you have a 15 ohm 100 W resistor by any chance?  That way you can eliminate any extra noise induced by the DC load control loop.  You've already shown CR is noisier than CC mode.

You can use use a lower voltage if you only have lower wattage resistors.  It also doesn't have to still be 2A to get a feel for if it makes any difference.
Even better if you can use a battery as the source.
 
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Offline electr_peter

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #157 on: October 25, 2024, 04:21:19 pm »
Here below is the setup of the lab power supply + the DC electronic load (which I put on a constant RESISTANCE).
Maybe I misunderstood the ability of the DC load to really maintain a stable resistance (or current) under a stable power source ?
CC mode works best, other modes (CR/CV/CP) are "indirect" with most DC loads and can produce "interesting" results.
Bottom line, use very stable current source (real resistor across PSU output) when checking stability of current probe.
« Last Edit: October 25, 2024, 07:47:51 pm by electr_peter »
 

Offline folays

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #158 on: October 25, 2024, 09:32:22 pm »
Thanks for you insights ;
I'm new to the electronic hobby ; See one of my adventure here : https://www.eevblog.com/forum/repair/repairing-a-robotic-pool-cleaner-zodiac-vortex-3/
  • In the above topic, for a pool cleaner robot, the propeller motor is powered at 28V and I measured the propeller motor at around 56 Ohm (disconnected, at idle).
    On my desk (above water  :)) The robot would put itself in a state of "fault" mode, and I guessed that the IC board were measuring propeller consumption Amperage,
    and thus was able to put itself to fault mode for safety reasons, thinking it somehow got out of the pool.
    The future (yesterday) proved me right, as soon as I plugged a DC load consuming those 28V at 20-25 Ohm or less (raising Amperage to 1.5 A), the robot behaved like it were submerged.
I often told myself, as in the case above, "damn right now I would like to have a purely resistive load, 28V at 1-2 Ampere in this case, so I would need something around 20 Ohm, not the most difficult I have a box of resistances, but I mainly need it to be able to dissipate 14 Watts of energy, not those pesky .125 Watts common resistances... Welp, let's buy a DC load....".

As a newbie, I only used for now Batronix and Eleshop, but they don't have neat low-resistance multi-watts resistances.
Would you have a shop recommandation for Europe/France ?

Unfortunately, on the supply side, I don't see where I could at home find 1A of battery DC current. Car's battery I would prefer not extracting it (car electronics sometimes reset unwanted stuff like remote keys), Power tools' batteries have circuitry unless I open their assembly, maybe I could take a bunch of AA batteries in parallel, I didn't checked their per-unit Amperage.

In the post linked by Martin72, I see the user have a https://www.siglent.eu/product/1149228/siglent-df2001a-power-analysis-deskew-fixture.
It's probably off-topic and of no help, but in any case, I own the Batronix Demo board https://www.batronix.com/shop/demoboards/Batronix-MSO-Demo-Board.html.

Quote
You're not triggering on channel 4, I'd change that if I were you.
I wanted to be in roll mode (continuous and rolling, not clearing-the-screen every time the horizontal span of time has been measured), I didn't yet figured out how to make Roll mode always behave like this, but I think that if I were to be (a) in Roll mode (b) set a correct channel (c) have the trigger level in the Amplitude region ; Then I sometimes have the Roll behaving like if the scope were to be in "Normal" mode (not "Auto" neither "Single") and not really "rolling", so until I understand why, when I want to "roll", I either set the wrong channel or set the trigger level outside of the Voltage amplitude.

Anyway, below are more refined scope settings, trying to copy Martin72's settings of https://www.eevblog.com/forum/testgear/micsig-cp1003cp503-100mhz50mhz-current-probe/msg5275105/#msg5275105 :
I changed the Timebase, Martin72 was at 1ms/div, I set my scope to 50us/div, and trigger to C4 "Normal" ;
Picture 1 and 2 are the same (just letting you on the (1) see the Channel settings, DC mode and BW 20M limit mode).
Picture 3 is at 10us/div.
I don't known why the "bands" are so much wide (multi-pixels height), I didn't enabled "Persistence" or something like that.

The Amplitude stills shows 144 mA.
Question is, regarding the Amplitude variation (which should be 2A stable in non-existing ideal setup), but is 144 mA which instruments are guilty ?
(a) could it be partly the CP503B but only for partially for up to 20-30mA variation ?
(b) the lab PSU and the DC load ?

Bonus question : I think that even if non-ideal, considering that the lab PSU is probably waaay less noisy than the DC load, would I be right regarding the lab PSU (SPD4036X) noise for being nearly non-existing (for being 10x much lower than the noise of the DC load), at least util then DC load is replaced by a "pure resistive load" ?

The amplitude is really sinusoidal-alike at 24k Hz, but I'm not knowledgeable enough to extract information from that.
I'm in Europe so mains is at 50 Hz (not 60), scope is 1 Ghz capable, CP503B should be able to measure up to 50 Mhz, at least 10 Mhz without huge distortions...

What I am observing here ? some ripple of the DC load ? What should I prioritize, finding a low-resistance 100 W ?
I own a broken 1000 Watts mains (230 V) resistive heater awaiting diagnostic. The resistor inside it should be around 50 Ohm I guess? And be able to dissipate... Maybe I should try that ?


Thanks & Best Regards,

EDIT : upload missing images.
« Last Edit: October 25, 2024, 09:34:37 pm by folays »
 

Offline folays

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #159 on: October 26, 2024, 12:39:29 am »
Hello again, I salvaged a mains' heater 1000 Watts measured at 55.32 Ohm, so around 0.54 Ampere for the same 30 V.
Below two capture, I set the DC load (Siglent SDL1020X-E) to the same CC than expected heater's resistor (0.55 A).

(again I moved the trigger out of the voltage level, I didn't want to post-analysis, so I wanted the scope' to roll freely)


First one shows the DC load, 62 mA of Amplitude (and Pk-Pk).
Second picture shows the pure resistive load, 11.294 mA of Amplitude (and Pk-Pk).

Sorry for the disturbance  :(, it was the DC load, the CP503B works better without an electronic DC load.

Best Regards,
 
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Offline Martin72

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #160 on: October 26, 2024, 02:03:09 pm »

Offline Kean

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Re: Micsig CP1003/CP503 100MHz/50MHz Current Probe
« Reply #161 on: October 26, 2024, 03:16:12 pm »
Hello again, I salvaged a mains' heater 1000 Watts measured at 55.32 Ohm, so around 0.54 Ampere for the same 30 V.
Below two capture, I set the DC load (Siglent SDL1020X-E) to the same CC than expected heater's resistor (0.55 A).

(again I moved the trigger out of the voltage level, I didn't want to post-analysis, so I wanted the scope' to roll freely)


First one shows the DC load, 62 mA of Amplitude (and Pk-Pk).
Second picture shows the pure resistive load, 11.294 mA of Amplitude (and Pk-Pk).

Sorry for the disturbance  :(, it was the DC load, the CP503B works better without an electronic DC load.

Best Regards,

Great!  I was just reading your earlier post and thinking to ask if you had a hair dryer or small fan heater you could check for resistance.

Some years ago I bought a handful of 50W and 100W power resistors in values like 1, 3.3, 5, 10, 22, 47, and 100 ohm, and mounted some on various heatsinks.  I have at least 6 programmable DC Loads and a few 2/4 quadrant power supplies, but a simple resistive dummy load can be very handy.

I have picked up some surplus resistors very cheaply over the years.  I think a large bag of 22 ohm 3W and tray of 10 ohm 25 W resistors have proved particularly handy.  I can wire these up in various series/parallel combination to make different loads.

A hot water heater element I bought was not expensive and turned out to be about 16 ohms and can run several kW in a bucket of water.  I've been planning to buy another to get 8 ohms.

These resistors can have some inductance that should be taken into account depending on what circuit you connect them to.
 


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