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Hantek CC-65 AC/DC Current Probe Teardown and Testing
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mickab:
Hello,

I'm currently searching a solution to increase the bandwidth of the clamp. The hall effect sensor seems to response up to 3MHz but the mod is design for +/- 1Mhz (Power supply design)
My first glance on this topic was very helpful. ;D

I have simulated the signal conditioning stage of the hall-effect sensor on Spice with a rudimentary model. An OPA2350 is used for U3 (high speed, low noise, single supply...) and a OPA2192 (high C-Load capacity) for the output stage.
The simulation is based on the schematic "cc-65-CLAMP.pdf" wich seems right except the capacitor value. I correct some cap value with few measurements. The correction is into the .pdf.

Push to the limit we can obtain 2.3MHz with +/- 170° phase shift and -3dB (see picture)

I will make a comparison soon with a new clamp vs modified.  ;)

jrf:
Mickab,

Very impressive, especially if the osc pages shown where actual measurements of your modified clamp in operation.
Simulation certainly has come a long way!
I would not have expected such a good result given the iron laminations in the head.
Shows how similar circuits from other suppliers can achieve good results, with better spec & correct components.
I am sure none of the original designs where optimised with a simulator.

PS: The version of cc-65-CLAMP.pdf used is not the latest on the site. ie some corrections & updates & most capacitor values updated, but not surprisingly a little different to your measurements. I suspect errors, changes or quality will change these with batches.

Cheers,
John.


Mechatrommer:

--- Quote from: mickab on November 11, 2020, 03:21:32 am ---The hall effect sensor seems to response up to 3MHz but the mod is design for +/- 1Mhz (Power supply design)

--- End quote ---
yeah good job. the reason i didnt pursue modding my clamp is because i saw some datasheets about cheap grade hall sensor their BW rating always in KHz region, the opamps used in the clamp is in MHz BW region iirc. so i concluded the bottleneck is the hall sensor and any mod attempt on circuit or IC will be futile. good to hear that i'm wrong.
mickab:
Hello,

See in the .PDF the full test comparison.  :)
 
Mechatrommer:

--- Quote from: mickab on November 13, 2020, 03:29:21 am ---Hello,
See in the .PDF the full test comparison.  :)

--- End quote ---
in your pdf stated to change U4 with OPA2195. i cant find what is OPA2195, no datasheet in internet... but in your earlier picture, suggesting to change U4 with OPA2192, so i guess OPA2195 is a typo?... i'm currently adding stuffs into lcsc cart, so i want to add this stock as well. i can find OPA2350 for U1,U3 but i cant find OPA2192 in DGK (vsop/pdso) package, only soic8. is there any specific reason why we cant use all U1,U3,U4 = OPA2350? why must U4 = OPA2192? kudos to your work and cheers.

edit: i just noticed your OPA2192 high C-load remark. so we cant use OPA2350? i'll check on this thanks.
edit2: checking schematics, there is no C-load directly subjected to U4, at least 1Kohm impedance in the middle.

observation:
OPA2350 is 7V max opamp (5.5V recommended operating voltage), battery in CC-65 is 9V so i think  need to buck down operating voltage to 5V, this probably will reduce maximum current spec from 6.5A to maybe 3A in lower range and 65A to 30A in upper range. for myself, i dont think thats a big problem, i never need to measure high current so far.
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