Why are proper current probes for scopes so expensive ?

[Martin72]

Hi everyone,

I want to share my thoughts coming in my mind when I´m observe the market what current probes for scopes concerns.
First thought, it seems that probes for scopes aren´t much desired by customers - passive probes, active probes, differential probes for voltage are more than enough there.
But current…?
Either they´re for AC measuring only, because of it´s simple design you can get a couple of them on the market, no big deal.
Or they´re for DC and AC measuring.
Then a hall sensor is used.
You can get it from hantek for a few bucks, or from owon, or by some brands using the same thing ( pintek = rigol = siglent = lecroy = keysight = rohde&schwartz).
It starts from appx 50 bucks and ends at 1000 bucks, depending from the bandwith and the brand itself.
But all have in common, they aren´t much precisely, in higher current ranges measures failures lies up to 15% and much more.
Also by the 1000 bucks probes 
You can buy a hantek cc-65 probe for 50 or a rohde&schwartz for 1000....differences between them are not so much as you would expected by the spending money.
Yes, a little deviation occurs, bandwith is a little bit better, noise level also.
But in general, it was crap.
To get a proper probe, you must take a huge step what pricing concerns.
4000, 5000, 6000 bucks...
These probes can therefore costs much more than your scope itself, wtf?!
And there is nothing between - Either you spend up to 1000 for a "crap probe" or you must take the big step and spend minimum 4000.
Why?
OK, to be honest, probes must have a proper supply, real noiseless for the small outputlevel. ( Think about good old tektronix system : Inputlevel must be 10mV on scope)
And to avoid saturation of the core element ( the reason why "cheap" probes have such a great measure failure on higher currents) you must have a compensation circuit for it.

Proper power supply and compensation circuits, OK, this can´t be cheap to realize.
In the 1970´s....
But we have 2020 now and it seems, today it can´t be affordable also.
Why ?
Can´t believe it...

Martin

[0culus]

Tektronix P6042 probes can be had for not outrageous amounts. I've collected four of them. One was fully restored by the prior owner (aside from replacing the probe cable with some more modern cable bundled up with heat shrink, it's like new) and it is in spec and works. The other three are in varying levels of working and I intend to rob them for parts as needed.

The probes are vulnerable to drop damage, and the cabling is prone to developing breaks in the very fine control wires that are routed with the two coaxes.

[Electro Detective]

It appears a LOT of test gear companies may be wayyy out of touch and clueless, especially from addon/accessories profit making ,
by not producing affordable TooHungLow sourced current probes and many other gadgets for oscilloscopes, be they DSO or CRO

My pet beef is not having affordable TooHungLow sourced DSOs with FULLY ISOLATED SEPARATED channels and Trigger inputs, outputs,
and basically anything going in and out of the oscilloscope, including the USB and comm ports 

If one desires a mains or otherwise earthing/ground reference, the manufacturer SHOULD fit an array of hard switches etc
or a master link or switch to save money

Instead they continue releasing the same old tired single ended designs and overpriced corporat priced accessories to frustrate cash strapped battling owner users,
as well as ignore the fact clueless or reckless death wishers will try and measure mains voltages or suspect grounded DC by thinking their DSO/CRO works like a floating multimeter   

And seriously folks, WHO doesn't want to see a current waveform on their screens as well as the voltage in real time or frozen? 
Why not jack the price of the DSO a bit and throw in a current probe or options to buy two, four..?

Unfortunately, it's not going to change anytime soon so don't hold your breath waiting, or buying into apologist BS.

China tech is cheap, we all know that, and a lot of product is good enough,
there's no excuse 'isolation' and 'current probes' are -expensive because..- for whatever feeble reasons in 2020,
or that Demand is low =     +     =   

[james_s]

There are a number of reasons. One is that the demand for current probes is far lower than for voltage probes, probably by at least two orders of magnitude. The probes are much more complex, their operation is simple in concept but the devil is in the details. Try building a clamp probe that is reasonably linear from a few tens of Hz to a few tens of MHz and see how easy that really is. If it was easy to build cheap ones that worked well someone would already be offering them.

[HighVoltage]

Even DC Probes are difficult to keep in tolerance and that makes them expensive.
And, quantity sold is very low compared to voltage probes.

But, if you have time you can get very good current probes on the secondary market for reasonable cost.

[tautech]

It appears a LOT of test gear companies may be wayyy out of touch and clueless, especially from addon/accessories profit making , by not producing affordable TooHungLow sourced current probes and many other gadgets for oscilloscopes, be they DSO or CRO

State your real requirements !

Peak amps ?
Max continuous amps ?
Frequency ? Max and min !
Insertion loss ?
Conductor size ?
Rigid or flexible design ?
Physical size/mass ?
AC or AC/DC ?
Isolation rating ?
Accuracy ?
Resolution ?

It should be plain to see that NO one size will fit all so the myriad of choices currently and historically available indicate they are specialist bits of gear and therefore not made in the millions so to be available to the masses for a few bucks like P6100 probes are. 

My pet beef is not having affordable TooHungLow sourced DSOs with FULLY ISOLATED SEPARATED channels and Trigger inputs, outputs, and basically anything going in and out of the oscilloscope, including the USB and comm ports 
If one desires a mains or otherwise earthing/ground reference, the manufacturer SHOULD fit an array of hard switches etc or a master link or switch to save money
Instead they continue releasing the same old tired single ended designs and overpriced corporat priced accessories to frustrate cash strapped battling owner users, as well as ignore the fact clueless or reckless death wishers will try and measure mains voltages or suspect grounded DC by thinking their DSO/CRO works like a floating multimeter   

Mine too but like quality current probes it's not piss simple. 
Full and safe isolation is a difficult task in a scope and just the price of isolated channel handheld DSO's reflect this without adding into the mix a mains supply, Ext Trig, Pass/Fail, USB, LAN isolation and operator safety too.
Further additional cost are probes suitable for isolated channel use with NO exposed metal and reference leads with shielded plugs and heavy clip insulation.
As some example just one of these costs more than four PP510 100 MHz probes:



For most differential probes serve this less common use type well and at affordable cost today where they can also double for measuring currents across shunts when they might not have a gnd referenced point.

And seriously folks, WHO doesn't want to see a current waveform on their screens as well as the voltage in real time or frozen? 
Why not jack the price of the DSO a bit and throw in a current probe or options to buy two, four..?

Again, a current probe you might be happy with, your mate won't as he will have different needs and even the selection of what's available pale in comparison to the decades old Tek designs like the 60 MHz P6021 or 100 MHz P6022.

Then how do we check current probe calibration and voltage/current probe skew ?
Add a current probe loop like in some old Teks or supply a current probe test fixture like this ?
Further additional cost. 

Unfortunately, it's not going to change anytime soon so don't hold your breath waiting, or buying into apologist BS.
China tech is cheap, we all know that, and a lot of product is good enough,
there's no excuse 'isolation' and 'current probes' are -expensive because..- for whatever feeble reasons in 2020,
or that Demand is low =     +     =   

You seem to think all this ^ is a simple one size fits all exercise however I can assure you it's not !

[Mechatrommer]

And seriously folks, WHO doesn't want to see a current waveform on their screens as well as the voltage in real time or frozen? 
Why not jack the price of the DSO a bit and throw in a current probe or options to buy two, four..?

we can see current using normal probe and $1 shunt resistor...if anything, if i dont like whats on the market, i'll try diy to appreciate why the price is (or is/should not).

[BravoV]

High end current probe market is DOMINATED and MONOPOLIZED by Hioki, everyone rebadges their products. Why would they make cheap ones?

+1 , bookmarked this particular page if I'm in the mood just to droll  -> Hioki CT6700 Current Probes as I can not afford them, this one's price can buy many-many DS-1054Z scopes.   

[Electro Detective]

High end current probe market is DOMINATED and MONOPOLIZED by Hioki, everyone rebadges their products. Why would they make cheap ones?

Thanks mate  I suspected some sort of monopoly or corporat market stifling going on 

You would think one of them might at the least dangle offer an affordable low bandwidth current probe, to keep up with multimeters and clamps which kick to 500 hz
and some can stretch out to 2khz

If people want 'ludicrous bandwidth' and accuracy, they gotta pay big dollar or DIY, hey I get that 

[coppice]

High end current probe market is DOMINATED and MONOPOLIZED by Hioki, everyone rebadges their products. Why would they make cheap ones?

Thanks mate  I suspected some sort of monopoly or corporat market stifling going on 

You would think one of them might at the least dangle offer an affordable low bandwidth current probe, to keep up with multimeters and clamps which kick to 500 hz
and some can stretch out to 2khz

If people want 'ludicrous bandwidth' and accuracy, they gotta pay big dollar or DIY, hey I get that 

The reason the current probe business is a near monopoly is its very small. Dave tried a current probe using a tiny flux gate, which is an innovative and interesting design. However, I doubt they've sold more than a handful, and had to finance the development of an entire new sensor for it.

[Sighound36]

The reason the current probe business is a near monopoly is its very small. Dave tried a current probe using a tiny flux gate, which is an innovative and interesting design. However, I doubt they've sold more than a handful, and had to finance the development of an entire new sensor for it.
[/quote]


I have one of the ITT probes and they are quirky but bloody useful especially for tight board work and silly SMPS around 600Euro +vat use this one at least once a week.

Martin the other current probe which we find very useful for sensible money is Pico Technology 30 A AC/DC precision current probe accurate to 1m/a cost is around 340 Euro'

https://www.picotech.com/accessories/bnc-current-probes/30-a-precision-current-probe-bnc

[Mr Evil]

High end current probe market is DOMINATED and MONOPOLIZED by Hioki, everyone rebadges their products. Why would they make cheap ones?

+1 , bookmarked this particular page if I'm in the mood just to droll  -> Hioki CT6700 Current Probes as I can not afford them, this one's price can buy many-many DS-1054Z scopes.   

That probe is exactly the sort of thing I would love to have, but likewise it costs multiples of my entire oscilloscope. There's no way it can actually cost that much to manufacture.

The closest I have to an affordable version of that (a low-current DC current probe) is a CP-06. It was cheap, but it's slow, too noisy to be usable for measuring currents of the order of milliamps, and the build quality is barely adequate.

[tautech]

High end current probe market is DOMINATED and MONOPOLIZED by Hioki, everyone rebadges their products. Why would they make cheap ones?

That's true to a point but there are starting to be other Asian options available.

PT-350
Bandwidth DC-50MHz
Peak current 60A
Max.current 20A RMS
Min.current 20mA
Accuracy 1%（±5mV）
Noise ≤3mA RMS
Rise time ≤7 ns
Terminal load 50Ω
Coupling AC/DC
Length 1.48m
Clamp dia. 5mm
Conversion ratio 0.1V/A

[supperman]

You can find this one for $200 on ebay..up to 1Ghz and super sensitive. Completely passive coil..amazing how it can drive into 50 ohm..
https://www.amazon.com/Tektronix-CT1-Frequency-Bandwidth-Accuracy/dp/B00A7GYISW

As a somewhat newbie I may be missing something, but it seems dead on accurate into 50 ohm over a high frequency range.. Of course will not do DC.. but I have a cheap one for that. And of course you need to wire it up.. but you kind of have to do that anyways with current probes. I use a breadboard patch cable which fits perfectly. (after removing the plug)

[tautech]

You can find this one for $200 on ebay..up to 1Ghz and super sensitive. Completely passive coil..amazing how it can drive into 50 ohm..
https://www.amazon.com/Tektronix-CT1-Frequency-Bandwidth-Accuracy/dp/B00A7GYISW

As a somewhat newbie I may be missing something, but it seems dead on accurate into 50 ohm over a high frequency range.. Of course will not do DC.. but I have a cheap one for that. And of course you need to wire it up.. but you kind of have to do that anyways with current probes. I use a breadboard patch cable which fits perfectly. (after removing the plug)

For most of us insertion is a PITA without a split core and high BW isn't really necessary.
Often a much cheaper option if we don't mind/can put up with insertion is an off the shelf CT or one from a SMPS current feedback loop.
FYI, attached is the Tek CT range spec and CT1/CT2 manual

[joeqsmith]

Yes, probes can be expensive.   I picked up an old LA a few years ago and wanted to some contactless and a few MICTOR cables for it.  The cables cost about 2X more than the LA. 

For home, I'm way too cheap to afford a nice clamp.  I have my old 1960's Tektronix that I rebuilt.  It drifts around a bit until it warms up but usable.  I wouldn't mind finding a new clamp with similar specs for under $100.   

[james_s]

You can find this one for $200 on ebay..up to 1Ghz and super sensitive. Completely passive coil..amazing how it can drive into 50 ohm..
https://www.amazon.com/Tektronix-CT1-Frequency-Bandwidth-Accuracy/dp/B00A7GYISW

As a somewhat newbie I may be missing something, but it seems dead on accurate into 50 ohm over a high frequency range.. Of course will not do DC.. but I have a cheap one for that. And of course you need to wire it up.. but you kind of have to do that anyways with current probes. I use a breadboard patch cable which fits perfectly. (after removing the plug)

The whole point of a current probe, and part of the reason they are so expensive is that they open up to slip over conductors without having to break the circuit and disconnect anything. If you don't mind opening the circuit you can use a differential probe across a sense resistor for a lot less money.

[supperman]

You can find this one for $200 on ebay..up to 1Ghz and super sensitive. Completely passive coil..amazing how it can drive into 50 ohm..
https://www.amazon.com/Tektronix-CT1-Frequency-Bandwidth-Accuracy/dp/B00A7GYISW

As a somewhat newbie I may be missing something, but it seems dead on accurate into 50 ohm over a high frequency range.. Of course will not do DC.. but I have a cheap one for that. And of course you need to wire it up.. but you kind of have to do that anyways with current probes. I use a breadboard patch cable which fits perfectly. (after removing the plug)

For most of us insertion is a PITA without a split core and high BW isn't really necessary.
Often a much cheaper option if we don't mind/can put up with insertion is an off the shelf CT or one from a SMPS current feedback loop.
FYI, attached is the Tek CT range spec and CT1/CT2 manual

Wait.. I want to understand this better. There are inexpensive current measuring devices that you can place on the board for testing? Can you offer me some key words so I can do some searches? I did not get very far with the above.

I'm dealing with high speed LED communications (in the 2-3ns switching range) and am having decent results with the coil.. but would totally embed components if there was a good non-invasive method. The less wire leads the better since this things wants to radiate.. The Ghz response is key.. (well.. on a 500Mhz tek scope)

[tautech]

You can find this one for $200 on ebay..up to 1Ghz and super sensitive. Completely passive coil..amazing how it can drive into 50 ohm..
https://www.amazon.com/Tektronix-CT1-Frequency-Bandwidth-Accuracy/dp/B00A7GYISW

As a somewhat newbie I may be missing something, but it seems dead on accurate into 50 ohm over a high frequency range.. Of course will not do DC.. but I have a cheap one for that. And of course you need to wire it up.. but you kind of have to do that anyways with current probes. I use a breadboard patch cable which fits perfectly. (after removing the plug)

For most of us insertion is a PITA without a split core and high BW isn't really necessary.
Often a much cheaper option if we don't mind/can put up with insertion is an off the shelf CT or one from a SMPS current feedback loop.
FYI, attached is the Tek CT range spec and CT1/CT2 manual

Wait.. I want to understand this better. There are inexpensive current measuring devices that you can place on the board for testing? Can you offer me some key words so I can do some searches? I did not get very far with the above.

CT = current transformer. 

I'm dealing with high speed LED communications (in the 2-3ns switching range) and am having decent results with the coil.. but would totally embed components if there was a good non-invasive method. The less wire leads the better since this things wants to radiate.. The Ghz response is key.. (well.. on a 500Mhz tek scope)

This makes it difficult, really difficult and I don't know of off the shelf solutions, sorry. Others might. 

[james_s]

I'm dealing with high speed LED communications (in the 2-3ns switching range) and am having decent results with the coil.. but would totally embed components if there was a good non-invasive method. The less wire leads the better since this things wants to radiate.. The Ghz response is key.. (well.. on a 500Mhz tek scope)

I've never even heard of a current probe with 1GHz bandwidth, even a voltage probe needs to be relatively exotic to achieve such bandwidth, I'm not aware of any DIY solutions that even come particularly close. Your best bet is probably a non-inductive sense resistor coupled with a high speed active differential probe.

[supperman]

I guess I'm using the correct tool then.. the Tek CT1 is responsive.. at least to what my scope can measure.. and down to very low current. I don't know how it is possible either.. I don't have it setup right now or I would share pictures.. ran tests be directly driving current with my 500mhz SDG6k

[james_s]

The fact that you're seeing something on the scope doesn't guarantee that what you're seeing matches what is actually there.

[tautech]

I guess I'm using the correct tool then.. the Tek CT1 is responsive.. at least to what my scope can measure.. and down to very low current. I don't know how it is possible either.. I don't have it setup right now or I would share pictures.. ran tests be directly driving current with my 500mhz SDG6k

If you're close to replicating risetime specs for the SDG6kX you can be reasonably confident with your CT1 and scopes performance.

[supperman]

I guess I'm using the correct tool then.. the Tek CT1 is responsive.. at least to what my scope can measure.. and down to very low current. I don't know how it is possible either.. I don't have it setup right now or I would share pictures.. ran tests be directly driving current with my 500mhz SDG6k

If you're close to replicating risetime specs for the SDG6kX you can be reasonably confident with your CT1 and scopes performance.

Yes, This. I was left with a feeling that the voltage readings correctly matched the current readings when driving into a linear resistor. (50 ohm). Diodes are then a leap of faith.. but I think it is good enough for what I need.

[Harjit]

I would love to find a clamp on oscilloscope current probe that went from 1mA / 10mA to 10A with a 1MHz bandwidth that was ~$200 but no luck... Any ideas?