Dear Ahmed

Attached, please find a suggested solution.

Regards

Hasan Al-Nashash

Ahmed,

In order to measure a capacitance of a capacitor, there is many measuring method but perhaps the mot suitable one using a differential amplifier is to derive the capacitor by a voltage ramp dv/dt and sensing the current passing through the capacitor by inserting a current sensing small resistance Rm in series with the capacitor. Assuming that the current is ic, then the voltage drop across Rm ic Rm= Vm. This voltage can be acquired by the differential amplifier.

On the other side, by definition ic= c dv/dt. This result finally in

c= Vm/ (Rm. dv/dt). Then one calculates c by measuring Vm at the output of the differential amplifier. Both Rm and the voltage ramp dv/dt can be chosen to measure c with good resolution.

hope this satisfies your imagination.

wish you success 

Thank you Dr. Hasan

Thank you Dr. Abdelhalim yes it sure gave me a push :)

You need an oscilloscope.  Configure the capacitor in an RC series circuit and charge the capacitor with a battery.  Measure the time constant of the resulting charge curve.  That will allow you to calculate the capacitance.  

Good luck.  

Thank you Dr. Zigang but my problem is i need the results to correspond in-real time.

You may want to look into adaptive control and parameter identification literature.