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ESR meter questions

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I'm learning how to use an ESR meter and need help with interpreting the results when measuring capacitors and transistors.

First of all, this is a Chinese cheap meter bought on amazon... a "BSIDE ESR02 Pro"


I have tried testing the same 1uF/35V   capacitor both in and out of circuit with the ESR meter.

In circuit:

Capacitance = 2.598uF   
Vloss = 3.1%   
ESR = 3.2 Ohms

Out of circuit:

Capacitance = 0.955uF   
Vloss = 0.1%   
ESR = 2.9 Ohms

Cap #7 in below schematic is the one tested.

How should I interpret these results, and what values should I ignore?

Should I ignore the capacitance result from the in circuit test and only look at the ESR?
The ESR value seems to be about the same both in and out of circuit.

What about V-loss? Can I look at V-loss in circuit or is it only valid when testing out of circuit?
Here the results are quite far apart with a x30 increase in VLoss when measuring in circuit.

The back of the ESR-meter has a table and it says "1uF/35V cap - 9 Ohms". Does that mean that as long as the cap reads 9 ohms or under, it is a good cap? Is this true both in and out of circuit?


Results from the transistor measurement:


The transistor is detected as a N-JFET
Pins functions are detected: (see picture)
I = 0.71mA@Vg=0.49V

I'm not sure what the numbers mean?

I only tested the transistor out of circuit, I'm not sure if I can test a transistor in circuit with the ESR meter...can I?

As for capacitor measurements: this meter is typical simple RLC and transistor multy-tester. It doesn't have in-circuit measurents feature so it is intended to use only off-circuit.
As for what to look at: you may look at datasheets of parts under test. You may compare only parameters stated by manufacturer. That's capacitance for capacitors and ESR for low-ESR capacitor types. If you test not low-ESR capacitor (e.g. general use or high-temperature type) you may check its ESR too - it is typically 2-4 times larger then similar low-ESR.

You may use Vloss parameter too but it is used by multy-tester manufactufers only and it is not used by capacitor manufacturers typically so you have to gather your own database for it. Typically low Vloss is ok (IDK,  < 5%) and high Vloss is not ok (>10..20% possibly). I use professional RLC-meter which doesn't have this parameter so IDK about it much.

If you check the user manual for a Peak Instruments ESR meter, it gives typical values for a range of capacitors:


Incircuit measurement is done at low voltage levels. That multi tester use ~5V pulsed source . When some Vbe(0.65V) is clamping and code is not enough advanced to detect it (continous sampling? could help)

Wallace Gasiewicz:
These inexpensive BSIDE component testers are amazing.I have one and it is accurate enough for my hobby needs. It is invaluable for testing transistors. The Resistance and capacitance measurements are quite good also.The usefulness of even the meters designed for in circuit testing is very limited, this one is not for in circuit testing as you have discovered. Any meter will only measure the value that is obtained in the circuit with every other component attached and affecting the reading.The in circuit testers that I am familiar with just use a very low voltage that is lower than a typical PN junction voltage to try to eliminate the effects of transistors on the reading. This is sometimes helpful but not a tremendous advantage.
Most inexpensive testers will not test at low values of cap and inductance. The BSIDE will not either.


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