Help! How to choose a proper current probe for my oscilloscope?

[ali6x944]

Hi everyone,
I was doing some repairs on a cuple of SMPS and other ac appliances and I needed a way to measure current and voltage, the way was using a 5w 1 resistor and two probes across the resistor to measure the voltage potential, well it is fine  if I want to measure power delivered to a load but not to great for my application so I want an expert recomendation on this subject...
Thanx a lot for all help

[ali6x944]

Anyone??

[Simon]

no idea to be honest I've not used current probes. If you want to effect your circuit less you could use a smaller shut like the ones used for high current and then amplify the voltage. For example the uCurrent is in effect a prtecision x100 amp so set to the nA range the input impedence would be 10K with is nothing to the micro ohms of a shunt resistor.

[stoica adrian]

Depending on your application.
You have to choose: Bandwidth, Attenuation ratio, Input impedance, Dynamic range, and look for compatibility with your scope.

[ali6x944]

Thanx a lot for the info, is there any other parameters I have to check be for I buy the current probes

[ali6x944]

Could I just make my own current probe?

[ebclr]

This little guy will help you a lot





http://pt.aliexpress.com/item/Free-Shipping-Hot-Sale-ACS712-30A-Range-Hall-Current-Sensor-Module-ACS712-Module-For-Arduino-30A/32515954572.html?spm=2114.02010208.3.10.rHrJwO&ws_ab_test=searchweb201556_0,searchweb201602_3_10057_10056_10065_10037_10055_10054_10069_301_10059_10033_10058_10032_10017_10070_10060_10061_10052_10062_10053_10050_10051,searchweb201603_2&btsid=b47076d6-b514-4047-9df3-235c2a6a8ed0

[tautech]

Could I just make my own current probe?

You can, I did for my first one but always yearned for a proper one.

I used a small CT from an old PC PSU and roughly calibrated it using a borrowed current probe with a resistor across its output. Trouble was there was no way to measure anything without breaking the circuit and soldering a wire through the hole in the CT. Worked fine up to a few KHz.
How I have a couple of P6021's, AC only, 15A max and 60 MHz rated. 

[Ice-Tea]

The iProbe 520 is very nice. But as said before: list your requirements first.

[ebclr]

You can also try a ready product like this one



http://pt.aliexpress.com/item/Hantek-CC-65-han-tai-oscilloscope-probe-current-AC-DC-AC-DC-current-clamp-measurement/32652508070.html?spm=2114.02010208.3.2.2CmG7V&ws_ab_test=searchweb201556_0,searchweb201602_3_10057_10056_10065_10037_10055_10054_10069_301_10059_10033_10058_10032_10017_10070_10060_10061_10052_10062_10053_10050_10051,searchweb201603_2&btsid=8efb74ec-cd21-46b1-ba9a-1b65366fe670

[ali6x944]

Could I just make my own current probe?

You can, I did for my first one but always yearned for a proper one.

I used a small CT from an old PC PSU and roughly calibrated it using a borrowed current probe with a resistor across its output. Trouble was there was no way to measure anything without breaking the circuit and soldering a wire through the hole in the CT. Worked fine up to a few KHz.
How I have a couple of P6021's, AC only, 15A max and 60 MHz rated. 

it is a good idea but dose it measure low frequency ac

The iProbe 520 is very nice. But as said before: list your requirements first.

a frequency of 100 MHz is fine
Attenuation ratio: x10
measure DC as well as AC
 Dynamic range i really did understand what is it , could u explain briefly please.
 

[tautech]

Could I just make my own current probe?

You can, I did for my first one but always yearned for a proper one.

I used a small CT from an old PC PSU and roughly calibrated it using a borrowed current probe with a resistor across its output. Trouble was there was no way to measure anything without breaking the circuit and soldering a wire through the hole in the CT. Worked fine up to a few KHz.
How I have a couple of P6021's, AC only, 15A max and 60 MHz rated. 

it is a good idea but dose it measure low frequency ac

AC only.
How low do you want to go? 

[oldway]

For ac+dc, LEM PR200 clamp.
It's discontinued now but you may perhaps find a used one for cheap.

[Ice-Tea]

The iProbe 520 is very nice. But as said before: list your requirements first.

a frequency of 100 MHz is fine
Attenuation ratio: x10
measure DC as well as AC
 Dynamic range i really did understand what is it , could u explain briefly please.

[/quote]
Pretty much: what's the lowest and highest current you want to measure.

And if you want 100MHz, be prepared to spend a lot if money.

[oldway]

A 100 Mhz current probe for doing some repairs on a couple of SMPS and other ac appliances
Are you kidding ?

Did you not understand that 100Mhz and attenuation x10 are not especifications of a current probe but are especifications of a voltage oscilloscope probe ?
ali6x944 is a beginner and he can't give especifications of what he need.
You don't even need a current probe to repair SMPS...

[Ice-Tea]

...ali6x944 is a beginner and he can't give especifications of what he need.

Which is why he is posting in the beginners section. To get advice and to learn. Probably not to be laughed at.

[oldway]

...ali6x944 is a beginner and he can't give especifications of what he need.

Which is why he is posting in the beginners section. To get advice and to learn. Probably not to be laughed at.

I'am laughing of the NON BEGINNERs who are answering at ali6x944 asking him especifications of the current probe, when he come here just because he don't know what he need and other people who would let him buy a very expensive 100 Mhz current probe that is only needed in a SMPS developping workshop.

[ali6x944]

A 100 Mhz current probe for doing some repairs on a couple of SMPS and other ac appliances
Are you kidding ?

Did you not understand that 100Mhz and attenuation x10 are not especifications of a current probe but are especifications of a voltage oscilloscope probe ?
ali6x944 is a beginner and he can't give especifications of what he need.
You don't even need a current probe to repair SMPS...

True , I might over exaggerate the value thanx for correcting me ....
I'm new to all the current probe stuff... the farthest I went in measuring current was the method mentioned earlier,  so please help others and me to choose the "proper" probe for their purpose.

[ali6x944]

The iProbe 520 is very nice. But as said before: list your requirements first.

a frequency of 100 MHz is fine
Attenuation ratio: x10
measure DC as well as AC
 Dynamic range i really did understand what is it , could u explain briefly please.

Pretty much: what's the lowest and highest current you want to measure.

And if you want 100MHz, be prepared to spend a lot if money.
[/quote]
Wait it isn't the same type of attenuation as in voltage probes?

[oldway]

Wait it isn't the same type of attenuation as in voltage probes?

No, the specification is how many mV or V by A or mA.
A 100Mhz current probe (with power supply and amplifier) costs thousands of $ ...

[ali6x944]

Ok...
 I got it now

[bson]

Are you measuring the mains side, the output side, or both?  They require very different tools.

[CoffinDodger]

I'm probably completely off but what I'm thinking is an AC/DC milliamp clamp meter would be the ticket if all you care about is magnitudes on the input and output. Not the waveforms, looking for harmonics and such..  not cheap but way cheaper than trying to outfit your scope I would think.    I hope I'm not missing something here.

[PTR_1275]

I bought one of the Hantek cc-65 clamps someone posted earlier. Be careful as some people sell them with banana jacks (but the photo is with BNC connector)

It isn't the flashiest out there, but it has worked for all my applications so far. I'be not needed accuracy (so far) just to see the current waveform.

[Bukurat]

Could I just make my own current probe?

You could, but what do you want to measure?  Current probes are essentially a one turn transformer with a split core and measure AC only.   I have a Tektronix P6021 probe that is at least 30 years old  that I use for non invasive in circuit measurements. These are still available and still pricey.

If you want to measure the AC input current there are other options. I use a meter I picked up off eBay http://www.ebay.com.au/itm/191929341893?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I mounted this in a plastic case and spliced the meter into a short extension cord.

For measuring AC current.
You can make your own current probe using one of the YHDC split core sensors. SCT-013-030 Has a built in burden resistor and gives 1V output at 30 amps.   http://garden.seeedstudio.com/images/b/bc/SCT013-030V.pdf

SCT-013-000 doesn't have a built in burden resistor. You can tailor the output voltage/mA with your own burden resistor.

For DC you need a Hall effect current sensor. Google it, there is a lot of info out there.