Multimeter measures the capacity at a constant current?

Question

Multimeter measures the capacity at a constant current?

Millimetre (RLC-meters) without the frequency selection measure the capacity of DC?
And RLC-meters to select the frequency of the measured capacitance on alternating current? And the multimeter can't measure capacitance with direct current?

As can be understood following the proposal of measuring capacitance With the piezoelectric transducer: "The value of C should be measured by an AVO meter under Dc state". As I understand AVO meter is a multimeter. What can be meant by "an AVO meter under Dc state"?

Electronics

gerry5 asked April 19th 20 at 12:21

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4 answers

naomie.Aufderh answered on · Accepted Answer · 2020-04-19T10:23:38.843Z

Yes, the usual multimeters do capacitance measurement and inductance alternating current. But the way to measure capacitance at a constant current is. You can use the parameter "time constant of an RC circuit":

$31707e49ef0fd027148d15a6b8c0514ad2354d1b$
Charges the capacitor to a known voltage, then discharged him to a resistor with known resistance. At the time of connection of the resistor it is necessary to start the stopwatch, and when the voltage on the capacitor will drop by about two-thirds (exactly - to the level of 36.8% of the original), the stopwatch will show the value of the time constant (Tau, in the formula above). Knowing Tau and resistance, this formula is elementary, the calculated capacity.

dedric_Ortiz answered on · Accepted Answer · 2020-04-19T10:25:38.843Z

dedric_Ortiz answered on April 19th 20 at 12:25

Solution

no. neither capacity nor inductance does not manifest itself at a constant current.
need either changing the value of the current/voltage to figure out what is the capacity/inductance of the element.

for capacity there is usually a simple scheme of the generator of a saw on direct current. pulse frequency is inversely proportional to the capacitance and directly proportional to the amperage (it switches for different ranges of capacity).
the frequency of the pulses considered timer percent is converted to capacity and display.
with the inductance of the circuit LC-oscillator with a set of containers. the actions are similar.
nothing complicated to itability will not.

How then can we understand the following sentence about the measurement of capacitance With the piezoelectric transducer: "The value of C should be measured by an AVO meter under Dc state". As I understand AVO meter is a multimeter. What can be meant by "an AVO meter under Dc state"? - gerry5 commented on April 19th 20 at 12:28

no. neither capacity nor inductance does not manifest itself at a constant current.

And transients? )
The time to charge the capacitor or a current surge when connecting the inductance can be measured and display the capacitance or inductance - abraham commented on April 19th 20 at 12:31

@abraham, Duc about this is the following sentence "you need any changing the value of the current/voltage to figure out what is the capacity/inductance of the element."
the measurement of a single process difficult and ineffective. it is better to measure a bunch of them are the same, i.e. the generator. a plurality of smooth systematic errors of individual processes, etc of Metrology.
well, how much easier it is to measure the frequency of 1 MHz than the duration of a single transition duration 0,000001 seconds. this is from the point of view of the applied circuitry. - dedric_Ortiz commented on April 19th 20 at 12:34

@gerry5, damn, I had to immediately write about photoelement, it is somewhat different. Probe more complex element than a capacitor. its equivalent circuit consists of several capacitances and inductance. the frequency response of a complex shape, has two resonance points, etc.
here under the dimension of an AVO meter under Dc state will assume a mean capacitance measurement at low frequency, almost DC. there are other methods for measurement of vessels using the high frequencies is usually measured and some associated characteristics of the parasitic inductance, resistance, cos φ, etc.
capacitance probes usually measure for a simple health check - with the destruction of the crystal capacity drops sharply. - dedric_Ortiz commented on April 19th 20 at 12:37

@dedric_Ortiz, the article where I got the quote atut capacitance probes need to measure to calculate inductively inductor, used to match probes to a generator. So the diode in which the capacitance is a temporary method not available? - gerry5 commented on April 19th 20 at 12:40

@gerry5, XS. the idea of the Creator are inscrutable. I just described the simplest and therefore the most shirokolistnyj method.
where to apply your PEP and why you need approval ??
all the same, PEP is usually used at the resonance frequency. and the resistance of the probe at this point has a minimum of reactive components. why external inductance/capacity question.
can describe in simple language what you need ?? I didn't tie to extract from you the information pincers to help :) - dedric_Ortiz commented on April 19th 20 at 12:43

@dedric_Ortiz, PEP is used in the low frequency bands of defektoskopie. The working frequency is approximately from 30 to 150 kHz. Emitting transducer operates at the resonance frequency, a receiving transducer at a frequency of antiresonance. The magnitude of the reactive component of the resistance of the transducer region of the resonance of about minus 3 ohms. You need to agree on a generator output detector/amplifier with the radiating transducer and the input of the receiving amplifier of the receiving transducer to increase the signal-to-noise ratio at the receiving device. On sale is a high frequency ULTRASOUND probe with a built-in inductance and in the literature on inspection there is a description of approval high-frequency transducer with a generator with inductance. - gerry5 commented on April 19th 20 at 12:46

clyde_Grady64 answered on · Accepted Answer · 2020-04-19T10:27:38.843Z

clyde_Grady64 answered on April 19th 20 at 12:27

Solution

To measure capacitance or inductance can be both a frequency and a temporary method. Moreover, for some nonlinear or polar entities may only a temporary method will be applicable.
The context would be in detail.

AVO meter - Dada, that Amper,Volt,Ohm meter

Need to measure the capacity of ployment to calculate inductively inductor, used to match the piezo generator. In the article about the agreement there are only these two offer about the measurement of capacity: "The value of The static capacitance C is formed by the connection lines of the transducer and its two surfaces. The value of C should be measured by an AVO meter under Dc state.". - gerry5 commented on April 19th 20 at 12:30

@gerry5this supposition: apparently when you try to measure capacitance of the piezoelectric element alternating current, you can get very strange results once the measurement frequency or its harmonics in the resonance zone of the piezoelectric element... - clyde_Grady64 commented on April 19th 20 at 12:33

harmon answered on · Accepted Answer · 2020-04-19T10:29:38.843Z

Time is a piezoelectric transducer, then it is possible the strong dependence of the capacitance from the applied voltage. Have in mind, it is likely that the measurement should be done with the same [average] level of DC voltage, which is applied to the transmitter in a real circuit.