Capacitance Measurement

[Xaotic]

In here I am asked to design at least two methods to measure the capacitance and the quality factor. We cannot use DC in this experiment.
Well first of all I thought of a series resistor but I was not sure about it so I need help about this.

 

[Dan Mills]

You might want to think about resonance, possibly as part of an oscilator circuit....

The 'impedance measurement handbook' form HP/Agilent is available on line and covers the pros and cons of many methods.

Regards, Dan.

 

[Xaotic]

Thanks Dan
Is there any other suggestions with extended explanation please?

 

[Xaotic]

Capacitance in a circuit



Do you guys have any idea? to find the capacitance in here

 

[adi0803199]

Re: Capacitance in a circuit

What do you mean by the question that you have posted,The value of capacitance is mentioned in the schematic.Do you mean to ask how to measure the capacitance in the circuit or the net Impedence in the circuit.The capacitance is given by X_c=1/j*(ωC)=1/j*(10 nF*2*(pi)*20 M).

 

[Xaotic]

Re: Capacitance in a circuit

What do you mean by the question that you have posted,The value of capacitance is mentioned in the schematic.Do you mean to ask how to measure the capacitance in the circuit or the net Impedence in the circuit.The capacitance is given by X_c=1/j*(ωC)=1/j*(10 nF*2*(pi)*20 M).

In here I am not going to know the capacitance when implying this circuit but it is close to that value. So I need to understand the concept for finding the capacitance by a "method". Like tuning the circuit and then finding the resistance, after this with 2*pi*f = (L* C) ^(1/2) I must find the capacitance.
A method like this.

 

[FvM]

Regarding the post #4 circuit:

In principle, the capacitance can be determined from the voltage ration V(c1)/V(V1), measured as a vectorial quantity, presumed that the resistor values are known.

Practically, the capacitor's reactance at 20 MHz will be about 0.8 ohms, almost shorting V(c1). In so far you'll want to chose more suitable resistor values and/or a lower measurement frequency. 20M in SPICE syntax means 20 Millihertz, by the way.

A more general way to determine component values from voltage ratios is a bridge circuit, e.g. a Wien bridge.
https://en.wikipedia.org/wiki/Wien_bridge
https://en.wikipedia.org/wiki/Bridge_circuit