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Smart LCR tweezers LCR Pro1-Russian RLC tweezers HB-14

Harald Kapp

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There ar a few limitations stated in that patent:
- The DC current through the rest of the circuit needs to be small, the patent states < 20 % of the DC current used to measure the capacitance in step 1.
- The capacitor is assumed to be the dominant reactive component.

Furthermore I doubt that this patent has been applied in constructing the tweezers.
 

caps

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I showed this patent as an example to answer your question about the influence of other components in in-circuit measurements.
This patent, of course, is not related to tweezers.
 

Harald Kapp

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I showed this patent as an example to answer your question about the influence of other components in in-circuit measurements.
And indeed this patent asserts that other components may have an influence.

Consider the simple case of two (or more) capacitors in parallel. This is a typical application e.g. in power supply decoupling. When you try to measure the capacitance you will measure the total capacitance of all capacitors. The instrument cannot distinguish between the capacitors unless all the other capacitors (except the one to be measured are removed from the circuit.
Of course it is usually much, much easier to remove the one capacitor to be measured from the circuit and then measure it separately.
 

caps

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And indeed this patent asserts that other components may have an influence
This is claimed by all and sundry, but nowhere is there any evidence of this.
Let's not repeat these arguments, but rather give specific examples where it is impossible, in your opinion, to measure the capacitor parameters in-circuit.
Describe more specifically these situations.
 

Harald Kapp

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Let's not repeat these arguments, but rather give specific examples where it is impossible, in your opinion, to measure the capacitor parameters in-circuit.
I did in post #63.
 

caps

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Consider the simple case of two (or more) capacitors in parallel. This is a typical application e.g. in power supply decoupling. When you try to measure the capacitance you will measure the total capacitance of all capacitors. The instrument cannot distinguish between the capacitors unless all the other capacitors (except the one to be measured are removed from the circuit.
The parallel connection of capacitors is a separate case of in-circuit measurements.
It can be considered separately.
I meant the influence of other components on the reliable measurement of capacitor parameters, if any.
And give specific examples of such situations.
 

Harald Kapp

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The parallel connection of capacitors is a separate case of in-circuit measurements.
It can be considered separately.
You may consider any combination of components as a "special case".

Here is a typical example of an LC line filter (from this page):
744998Schaltkreis.png

When you try to measure Cx (it doesn't matter which one), you have to deal with:
  • Another Cx in parallel
  • A series connection 2 × Cy in parallel to Cx
  • A resistor in parallel
  • A varistor in parallel which not only has a resistance but also a comparatively large capacitance

If you don't trust my experience, trust the experts, e.g. this explanation.
 

caps

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The left side of the circuit.
There should be no problem measuring the capacitance of a film capacitor.
Capacitance of varistor S14K250 on datasheet-350pF.
 

caps

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Canadian tweezers LCR Pro1 will always be correctly measured in the most difficult situations of in-circuit measurements.
Resistor 0.005 Ohm.
 

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caps

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Two electrolytic capacitors connected in parallel. A good capacitor and a bad capacitor. 5.00-5.37.
Complete nonsense.
 

SHA_S

May 25, 2019
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No wonder. In-circuit measurements require shielding of the component to be measured from the effects of other components, wiring etc...
For measuring ESR of electrolytic capacitors, in-circuit, these tweezers (HB-14, HB-15) are perfect, because measurement voltage tens of mV and semiconductors do not affect the result. Resistors also have a small effect due to the large difference in resistance, because ESR 5-50mOhm, and resistors from 10Ohm or more.

Watch this moment carefully in the video.
6.48-6.58.
Measured SMD resistor 0 Ohm. Its name is a resistor-jumper.
The measurement results differ three times. So, it is absolutely not clear which of the tweezers can be trusted.
Poor contact, or poorly calibrated one of the tweezers, that's the whole secret in the discrepancy of the results.

Canadian tweezers LCR Pro1 will always be correctly measured in the most difficult situations of in-circuit measurements.
Resistor 0.005 Ohm.
And the hell to measure a shunt at 100 kHz? This measurement will make any device capable of measuring in the mΩ range anywhere in the circuit and 100 kHz here unnecessarily.

Two electrolytic capacitors connected in parallel. A good capacitor and a bad capacitor. 5.00-5.37.
Complete nonsense.
Not to understand what is shown in this part of the video, this is really nonsense.
 
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caps

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16.10-18.50
The measurement of 1500μF capacitors. Complete nonsense.
 

caps

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A logical question arises.
Why sell a raw product to people? The measurement results are terrible, the numbers on the display are unstable, the display spontaneously flips, the contact is not stable, constant calibrations are needed.
 

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SHA_S

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The measurement of 1500μF capacitors. Complete nonsense.
In the previous post, I named the reasons for these strange measurements, the device, most likely, has nothing to do with it.
Why sell a raw product to people?
To "earn" fast money, what else?
A deeply erroneous statement, for the reason I named earlier. NV-14 is the best device on the market in terms of price / functionality / accuracy / convenience / speed / stability. And the technical support is generally the best in the world.
 

caps

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To "earn" fast money, what else?
In my opinion, everyone understands this.
I can only say that the HB-14 tweezers ceased to exist for a number of reasons that I described earlier.
That's good. It was a toy for schoolchildren.
The next clone, HB-15, costs twice as much. But in fact it is the same raw product. All this is clearly visible in all videos.
 

SHA_S

May 25, 2019
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If HB-14 is a toy for a student, then LCR Pro1 is probably suitable for a kindergarten. We watch the video from 1:23, where you can clearly see what quality this craft has.
 

caps

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HB-14 is a primitive home-made product that has not reached a decent level of measurement quality. An unfinished program, a lack of knowledge and practical experience among developers, the use of cheap Chinese components, a terrible assembly with poor-quality soldering and unwashed flux, medieval quality of the probe and everything else say that, that it is better to do something yourself than to buy this toy.
 

caps

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Once upon a time, this toy had a maximum frequency of 10 kHz. The manufacturer naturally did not have enough brains to make 100 kHz right away. In fact, measuring at this frequency is associated with certain difficulties. But the Canadian engineers were able to solve them immediately.
Perfectly developed software. All features of measurements at a frequency of 100 kHz are taken into account. All features of measurements in the complex picoFarads and nanoHenry ranges are taken into account.
Electrolytic and polymer capacitors are measured with phenomenal accuracy.
Respect again to the Canadian engineers.
 

caps

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The HB-14 used the cheapest microcontroller with limited capabilities.
The developers have solved all the negative aspects at the expense of the poor controller, since its memory was not enough for everyone.
The PR people of this office did their best to embellish this toy as best they could, but they suffered a complete fiasco. NV-14 evaporated like smoke.
 
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