Measure capacitor ESR with any LCR meter?

[kc1980]

Can capacitor ESR be reliably measured with any LCR meter?  One would think that THAT is exactly what the LCR meter is designed to do, but there are other factors to consider (e.g. frequency).

[Zad]

I think it very much depends on the meter. Some meters are true L/C/R meters only, are very crude and only measure charge/discharge time or oscillation frequency in a simple circuit, others pass an AC voltage across the device under test and measure the phase and magnitude of the current. That makes it simple to derive the purely capacitive and resistive components.

As you say though, that is just at one frequency, and both R and C values can change massively with frequency. A cap that looks fine at 100kHz may degrade horribly at 1MHz. Ideally you want to be able to sweep the values, but then you start getting into the realm of scalar and vector network analysers.

[NiHaoMike]

I have read somewhere that if you have a signal generator, oscilloscope, and a known (low value) resistor, it is very easy to measure the ESR. Make a voltage divider out of the capacitor and resistor, set the frequency high enough that capacitive reactance is negligible, then measure the voltages.

[ThunderSqueak]

I have read somewhere that if you have a signal generator, oscilloscope, and a known (low value) resistor, it is very easy to measure the ESR. Make a voltage divider out of the capacitor and resistor, set the frequency high enough that capacitive reactance is negligible, then measure the voltages.

http://octopus.freeyellow.com/99.html 

Something like that?

[Pyr0Beast]

Can capacitor ESR be reliably measured with any LCR meter?  One would think that THAT is exactly what the LCR meter is designed to do, but there are other factors to consider (e.g. frequency).

No.

LCR meter measures inductance, capacitance and resistance, but not ESR of capacitor.
You have ESR meter for that.

[EEVblog]

Can capacitor ESR be reliably measured with any LCR meter?  One would think that THAT is exactly what the LCR meter is designed to do, but there are other factors to consider (e.g. frequency).

No.

LCR meter measures inductance, capacitance and resistance, but not ESR of capacitor.
You have ESR meter for that.

Actually, many of them do. The Extech LCR meter for example does.
It displays ESR on the secondary display.
But only at 10KHz.

Dedicated ESR meters are better if you are doing this sort of work though.

Dave.

[smpowell]

I have read somewhere that if you have a signal generator, oscilloscope, and a known (low value) resistor, it is very easy to measure the ESR. Make a voltage divider out of the capacitor and resistor, set the frequency high enough that capacitive reactance is negligible, then measure the voltages.

If you already have a function generator, look at: http://octopus.freeyellow.com/esr.html first.
 
My other page at http://octopus.freeyellow.com/99.html   includes the details about making a simple
square wave generator in case you don't want to use a separate function generator.

I'm probably going to simplify the 555 schematic on 99.html pretty soon as the old one is a bit more complicated
than it needs to be.

[TechGuy]

Can capacitor ESR be reliably measured with any LCR meter?  One would think that THAT is exactly what the LCR meter is designed to do, but there are other factors to consider (e.g. frequency).

The Sencore LC103 has ESR measurements. The LC103 also provides a programmable input voltage so you can measure ESR, leakage, etc while the cap is at operational voltage. Many LCR meters make measurements at low voltage which don't tell the full story about a caps performance, Leakage and ESR are typically much higher on bad caps when they are fully charged. http://www.sencore.com/products/general-test-measurement-equipment/75

The only anonyance is that you have to press and hold a button while it performs a measurement. This makes it hard to measure a component that you can't attach probes without holding the probes in two hands (ie Surface mount devices or in-circuit radial caps).