ESR meter 200kHz

[tigr]

Another serious problem with the ESR meters is related to the measurement of electrolytic s of less than 1 uF. In the ESR tables, these values are not available.

[The Electrician]

The main problem with all ESR meters is the ability to separate the active and reactive components from the capacitor.This depends on many factors,and primarily on the measurement method.In practice,most amateur circuits are not situable for measuring the ESR the film capacitors.

I will demonstrate using an example of a super-quality polystyrene capacitor 0.5 uF 250V 1%.

Exactly what are you demonstrating here? I see that there is considerable difference in the first two ESR measurements, and I don't know what the reading in the third measurement is.

It is to be expected that when measuring ESR using the pulse or square wave technique that the result will not be accurate when, at the frequency of measurement, the impedance of the capacitor is much larger than the ESR.  In that case the only way to get a good measurement is to use sine wave excitation.

There are some relatively low cost meters that use sine wave excitation, such as the DE-5000.  Do you have any meters that use sine wave excitation?

[ocw]

Do you have any meters that use sine wave excitation?

Attached is the 100 kHz capacitor evaluation waveform from my Extech LCR200.
The other test frequencies are similar sine wave signals.

[tigr]

and I don't know what the reading in the third measurement is.

0,005Ohm.
And where it is possible to read about the effect of the shape of the measuring signal on the measurement of ESR, tested in practice?

[ocw]

Do you have any meters that use sine wave excitation?

I should have also included the attached 100 MHz test signal that I use for capacitor evaluation from my AIMUHF analyzer.  It can test up to 1 GHz although eliminating the effects of the test "cable" becomes more difficult above 500 MHz.

[Jay_Diddy_B]

Exactly what are you demonstrating here? I see that there is considerable difference in the first two ESR measurements, and I don't know what the reading in the third measurement is.

It is to be expected that when measuring ESR using the pulse or square wave technique that the result will not be accurate when, at the frequency of measurement, the impedance of the capacitor is much larger than the ESR.  In that case the only way to get a good measurement is to use sine wave excitation.

There are some relatively low cost meters that use sine wave excitation, such as the DE-5000.  Do you have any meters that use sine wave excitation?

1+

I don't see anything in Tigr's design that is revolutionary or offers any significant improvements.

The design can be simplified a current source, a standard resistor and a current detector:



The MAX253 and the resistor form a current source. The current is split between a resistor, which I will call the standard resistor and the impedance of the capacitor being tested. The current through the capacitor under test is measured and displayed.

The meter will read a maximum if the impedance of the capacitor is zero. The meter will read half-scale if the impedance of the capacitor is equal to the standard resistor.

The impedance of the capacitor consists of three parts, the capacitance, the ESR and inductance.

The impedance is only equal to the ESR if 1/(2 x pi x Freq x C) = 2 x pi x Freq x L

So if the frequency is swept the results are:



Sweeping the value of C

If change the model. I have fixed the frequency at 300 kHz and I am sweeping the value of capacitance. I am measuring the RMS current in the capacitor under test.



Results with Resr = 10m



Results with Resr = 200m




The desirable result is to have the ESR reading independent of the value of the capacitor.

All this shows that it not possible to accurately measure the ESR of capacitor by simply measuring the impedance.

You need to also measure the phase angle or use a phase sensitive detector that measure the component of the impedance that is in-phase with excitation current.

The ESR adapter that I shared here:

https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg341177/#msg341177

This circuit uses a phase sensitive detector, which helps but it is not super accurate for low values of capacitance.

I have attached the LTspice models for those playing along at home.

The best DIY solution I have seen was done by Jaxbird:



https://www.eevblog.com/forum/projects/impedance-analyzer-build-and-experiments/

Unfortunately, some of the pictures are lost.


Regards,

Jay_Diddy_B

[tigr]

  In that case the only way to get a good measurement is to use sine wave excitation.

I once was interested in this issue,but in practice I never saw the difference.

[The Electrician]

and I don't know what the reading in the third measurement is.

0,005Ohm.
And where it is possible to read about the effect of the shape of the measuring signal on the measurement of ESR, tested in practice?

I explain it in reply #6, reply #7 and reply #8 of this thread: https://www.eevblog.com/forum/projects/impedance-lcr-esr-meters/msg459262/#msg459262

[tigr]

All this shows that it not possible to accurately measure the ESR of capacitor by simply measuring the impedance.
You need to also measure the phase angle or use a phase sensitive detector that measure the component of the impedance that is in-phase with excitation current.

For me, a simple practical criterion is important, when the result of the measurement is less than that indicated in the datasheet. This means that the device measures the real ESR.
Capacitor LOW ESR Rubycon MBZ 3300uF/6,3v.By datasheet max.ESR-0,012Ohm.
The ESR meter is with a synchronous detector. Measures a practically pure ESR. The result is in the table.
 My ESR meter shows 0.006 Ohm. Which sensitive detector is needed?

[tigr]

There are some relatively low cost meters that use sine wave excitation, such as the DE-5000.

I do not use instruments that give the same result of ESR at different frequencies.
Your topic was reading. Thanks.

[The Electrician]

All this shows that it not possible to accurately measure the ESR of capacitor by simply measuring the impedance.
You need to also measure the phase angle or use a phase sensitive detector that measure the component of the impedance that is in-phase with excitation current.

For me, a simple practical criterion is important, when the result of the measurement is less than that indicated in the datasheet. This means that the device measures the real ESR.
Capacitor LOW ESR Rubycon MBZ 3300uF/6,3v.By datasheet max.ESR-0,012Ohm.
The meter is with a synchronous detector. Measures a practically pure ESR. The result is in the table.
 My meter shows 0.006 Ohm. Which sensitive detector is needed?

Jay_Diddy_B was not talking about a capacitor with 3300 uF; he was talking about much smaller value capacitors.

I don't have a 3300 uF Rubycon, but I do have a 1800 uF 6.3 volt Rubycon.  Here is a sweep showing its impedance and ESR over a frequency range from 100 Hz to 5 MHz:



Notice that when the capacitance is large, the impedance and ESR are the same over a substantial range of frequencies, in this case from about 20 Khz to about 300 KHz.  A simple meter using pulse or square wave techniques will give a good result for ESR over that frequency range even though it is really measuring impedance, because the impedance and ESR are the same over that frequency range..  But with a smaller value capacitor may not be true.  Look at some of the sweeps I show in the linked thread.

[The Electrician]

There are some relatively low cost meters that use sine wave excitation, such as the DE-5000.

I do not use instruments that give the same result of ESR at different frequencies.

I don't understand what you mean by this.

[tigr]

http://www.murata.com/en-eu/products/emiconfun/capacitor/2013/02/14/en-20130214-p1

[tigr]

I don't understand what you mean by this.

I have no desire to detail these things.
Let us continue with the measurement of ESR of small capacitors.
ESR meter 100kHz.
0,1uF/63v.
0,22uF in the circuit.

[tigr]

Capacitor LOW ESR Rubycon MBZ 3300uF/6,3v.By datasheet max.ESR-0,012Ohm.
The ESR meter is with a synchronous detector. Measures a practically pure ESR. The result is in the table.
 My ESR meter shows 0.006 Ohm. Which sensitive detector is needed?

ESR-0,009Ohm.
This practically coincides with the measurement philosophy, which LCR Research showed with its tweezers.

[tigr]

Another complication of the ESR meters is the measurement of ESR of large capacitances.
For example.

[tigr]

  In that case the only way to get a good measurement is to use sine wave excitation.

I once was interested in this issue,but in practice I never saw the difference.

Square wave.
My first tweezers ESR, 100kHz, 5 years ago.
Capacitor Rubycon MBZ 3300uF/6,3v.ESR-0,007Ohm.

[tigr]

Capacitor LOW ESR Rubycon MBZ 3300uF/6,3v.By datasheet max.ESR-0,012Ohm.
The ESR meter is with a synchronous detector. Measures a practically pure ESR. The result is in the table.
 My ESR meter shows 0.006 Ohm. Which sensitive detector is needed?

ESR-0,009Ohm.
This practically coincides with the measurement philosophy, which LCR Research showed with its tweezers.

[The Electrician]

Capacitor LOW ESR Rubycon MBZ 3300uF/6,3v.By datasheet max.ESR-0,012Ohm.
The ESR meter is with a synchronous detector. Measures a practically pure ESR. The result is in the table.
 My ESR meter shows 0.006 Ohm. Which sensitive detector is needed?

ESR-0,009Ohm.
This practically coincides with the measurement philosophy, which LCR Research showed with its tweezers.

What are you trying to show us here?  Please include something more than pictures in your posts; some text explaining the purpose of the post would be good.

[BravoV]

Guess he obsessed with low ESR electrolytic caps, and keep posting meaningless photos of measured used caps.

[tigr]

Please include something more than pictures in your posts; some text explaining the purpose of the post would be good.

And what is there to explain?
It is clear that the russian tweezers, instead of showing the real ESR, shows the maximum permissible ESR-0.012Ohm.

[tigr]

The main feature of this ESR meter is the search for faulty film capacitors of low capacitance in the circuit.

Now,I want to show why the measurement of the tan d(D) is not suitable for this. It is necessary to measure ESR.
Bad film capacitor 1uF/250v.
A good film capacitor 0.47uF/250v.

[The Electrician]

Since D and ESR convey exactly the same information, there should be no reason in theory why one would be better than the other.

The relationship is D = ESR*(2*pi*f*C)

However, as a practical matter, for film capacitors measured at 1 kHz, the measurement of either D or ESR can be difficult because the ESR can be 3 or more orders of magnitude less than the reactance.  This may result in the value of D being given with only a single significant digit.  When converting this low precision value of D to ESR, the resulting ESR will also have only a single digit of significance.  If the numerical result appears to have more digits it should be kept in mind that many of those digits are bogus.

For example, your "bad" capacitor has a measured D of .0002; if we calculate ESR from this we get .1131, but the measured value was .090.  Or, going the other way, if we calculate D from the ESR value of .090, we get .00016 rather than the measured value of .0002

Here's some measured values of a film capacitor with a measurement frequency of 100 kHz.  At this frequency it's possible to get more than a single digit of accuracy.  In this case if we convert the measured value of D (.00996) to ESR we get .0398 which is very close to the measured value of .03984.  Or, if we convert the measured value of ESR (.03984) to D we get .00996 which is exactly the same:



But if we make a measurement of this same capacitor at 1 kHz, the measurement doesn't give as many significant digits for D, and the conversion of D to ESR doesn't give such a good match:



Converting D to ESR, we get 72.10 milliohms compared to the measured value of 73.82 millohms.

Measurements of a good film capacitor at 1 kHz are difficult with even a good bench instrument.  Measurements made with a tweezer instrument are likely to be very near the limit of the tweezer's capability, so we can't really expect highly accurate results.

[3db]

@The Electrician
I don't think it's going to matter,whatever you say to him. 

3DB 

[tigr]

3db
Did you want to say something on the subject?