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Hantek CC-65 AC/DC Current Probe Teardown and Testing

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Martin72:
Hi,

Had the CC-65 too, it´s behaviour in general was worser than the owon cp-05, which I got too (still have it).
The noisefloor kills it, probably this should be only used by multimeter.
Also the offset correction wasn´t stable.
The owon costs about 170€ incl. tax and is usable from 1A/div upwards, because of the noisefloor, the hantek in my memory too.
I wouldn´t recommending both, but the hantek is so cheap, it could be worth trying to improve it´s behaviour.


--- Quote ---But the quality of the core is very important so I don't think the circuit is the limiting factor .
--- End quote ---

Remember the tektronix current probes.
With their external, large supply/amplifier, the circuit does matter too.
It´s got current compensating measuring method, so in theory, the core would not get into saturation.
(Current compensation: A winding is on the core, the hall sensor detect the current flowing through the core and feed it into a regular circuit which controls the compensation winding on the core.
A compensating current will be generated which rises up until the current through the core is zero, which means that the core couldn´t get in saturation - this compensating current will be forwarded to the measure output.
If 1A is flowing through the core, then compensating current will be 1A - And this is, what you measure.
Also this method allows you to do easily degaussing.)
But the saturation also depends from the frequency of the current, so the material of the core is mostly not a single one, it´s a mix, an compound of several ones to get as high as possible.

Current Clamps like the hantek or owon or many others, even when they costs 1000, 2000 bucks, don´t have it at all, what current compensating/ degaussing concerns.
What you can do is to reduce the noisefloor, maybe shifting a little bit the bandwith.


belzrebuth:

--- Quote from: Martin72 on June 17, 2020, 08:39:47 pm ---
Had the CC-65 too, it´s behaviour in general was worser than the owon cp-05, which I got too (still have it).
The noisefloor kills it, probably this should be only used by multimeter.


--- End quote ---

Have you tried increasing/adding capacitors as described in this thread?

Martin72:
To be honest, no. Got it, test it, give it away...
Must read the thread completely, what the capacitors concerns.

jrf:
CC-65-CLAMP.pdf above shows one capacitor solution as described in this blog, labled NEW caps in the power supply.
These caps are specified by the voltage regulator manufacturer but where not fitted, from what I can understand.
As stated on CC-65 CLAMP.pdf it should be possible to put in a multi-turn trim pot to replace the Zero push button. Then so long as the unit is at 'temperature' & under steady state conditions the zero should be reasonably stable, unlike a charged capacitor zero circuit! Pots where used on all the name-brand clamps & I suspect the push button was used to simplify the unit for rapid use in non-tech fields, copying its use in meters. Unfortunately meters are able to use a computer to do Zero, & do not drift compared to this solution!

I have read here about the coils used in some clamps. On reading a repair blog I found a 10MHz unit said the coil actually measured AC & the Hall the DC component. This makes sense. A coil could also be used to 'zero' the hall reading to reduce DC-saturation, but does nothing for AC saturation. The photos on this blog clearly show steel laminations. The frequency response of these would probably affect the linearity of the clamp at higher frequencies.

The op-amps used & the current circuit will only do as specified. Op-amps with 10x the frequency response are available but with typically higher current draw or more $$.

John.

Noy:
Do somebody know pincompatible better ones (Opamp)?

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