Still I cant get around to understand how Inductance is measure without an AC signal being use. I'm having problems understanding the concept
Hello ilcaccillo
Extract from Karl-Heinz Kübbeler's documentation:
Transistor tester with AVR microcontroller Version 1.13k
Page 44
3.10 Measurement of coils
The normal measurement of the inductance is based on the measurement of the time constant of the
current grow. The detection limit is about 0.01mH, if the resistance of the coil is below 24Ω. For
bigger resistance values the resolution is only 0.1mH. If the resistance is above 2.1kΩ, this technique
can never be used to detect coils. The measurement results of this normal measurement is shown in
the second line (resistance and inductance). With the samplingADC method a resonant frequency
of coils can be detected with greater inductance values. If this effect is noticeable, the frequency and
the quality factor Q of the coil is shown additionally in line 3.
The method of resonant frequency measurement can also be used for the determination of the in-
ductance value, if a sufficient big capacitor mith know capacity value is connected parallel to a little
inductance (<2mH). With a parallel connected capacitor the normal measurement of inductance
can no more operate well. If the resonant frequency let assume a parallel connected capacitor, the
inductance of the normal measurement is not shown and the resistance value is shown in line 1. For
this resonant circuit the quality factor Q is also computed and shown behind the frequency value in
line 3. You can identify this type of measurement with the inductance value at the first position of
line 2, followed by the text “ if ” and the value of the assumed parallel capacity. The value of this
parallel capacitor can currently only be set with the calibration function (1-||- 3 10-30nF(L)).
For displays with only two lines, the content for the third line is shown time-delayed in line 2.
Greetings Horst