Products > Test Equipment
Hantek CC-65 AC/DC Current Probe Teardown and Testing
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jrf:
Most dual opamps are pin compatible & available in that case size.
Important things you need to look at:
Operation Voltage range. ie same or better than existing.
Frequency response. 10x existing.
most of the other specs equivalent or better.
Availability.

Changing just the op-amps may not change the frequency response of the overall circuit as some of the capacitors in the circuit may act as filters as well.  Breadboard a circuit & experiment with what needs to be changed or just look up a 'standard' instrument amp circuit with the desired frequency response & modify to suit this applictaion.  Capacitors are often added for compensation & can depend on the opamp used.

John.
belzrebuth:
@jrf
Could you do a basic test when you receive the unit and post a couple of screenshots here?
Maybe post something like a square into a load and the current rising and falling at half its stated BW and close to 20k?
I'd very much like to know when things start to break up.
With other words I wonder what could be the max frequency at which you can get a pretty looking waveform before discontinuities or other artifacts appear.
jrf:
Look at the posts on this blog for that! Lots of photos of outputs.
10KHz bandwidth means that a 10KHz sign wave is at 3db down (1/2 expected voltage) at 10KHz.
So a 1KHz square wave, which is made up of 1KHz, 3KHz, 5KHz, 7KHz, 9khz etc sign waves,  will be mostly square.
But by 10KHz all you get is a mostly 1/2 voltage 10KHz sign wave.

John.
jrf:
Well Aliexpress have delivered my Clamp & ,after a few quick measurements, the circuit is as I drew.
Scematic -  CC-65 CLAMP1.pdf (20.94 kB - downloaded 481 times.)
I have updated the voltage regulator values.

I shorted the 470uF zero cap for 30sec & then powered on & the output was 2mv at 1mV/10mA.
I then zeroed the unit & the cap chaged to ~10mv to offset this to zero.
2mV zero error is what I would expect. The temperature of my unit was ~20'c.
I would expect up to +/- 5mV based on temperature fluctuations & existing mag fields.
I turned off the unit for 2 hours & then back on (the capacitor charge should not be affected by the power switch pos).
It then read 1mV. So 1mV drift. (equiv to 10mA.) Very good.
Noise was ~1mV p-p without any mods. Have yet to test adding caps. I think 1mVp-p is reasonable!

I also put a magnet near the head. Big reading.
So if you short the Zero Cap & get a large value (zero offset) then the head may need demagnetising.
My Fluke is unafected by external mag fields!
If demagnetised & still high zero offset then may need to adjust Zero - step 6. VR3-4

Checking the calibration, mine looks to read 10-20% high!
Only tried DC to 2A. Will try AC & if the same error will calibrate to full scale on DC on both ranges.
(as described in the SChematic attached. Last section only, ie no need to adjust hall sensors, so just Steps 7 & 8.)

Further testing/calibration tomorrow.

Cheers,
John.
Martin72:
Do you know the name of the op-amps ?
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