Lab 5 RS

Go Back to All Lab Reports

LC Resonance circuits

The LC circuit

Design a parallel LC resonant circuit with a resonant frequency between 50-200 kHz. use [math]L[/math] = 10 - 100 [math]\mu H[/math], R = 1k [math]\Omega[/math]

[math]\omega_0=\frac{1}{\sqrt{\mbox{LC}}}[/math]

I choose the following values for [math]\mbox{L}[/math] and [math]\mbox{C}[/math]:

[math]\mbox{L}=33\ \mu H[/math]

[math]\mbox{C}=1.024\ \mu F[/math]

[math]\mbox{R}=0.989\ k \Omega[/math]

[math]\mbox{R}_L=2.5\ \Omega[/math]

So the resonance frequency is [math]\omega_0=\frac{1}{\sqrt{33\ \mu H \cdot 1.024\ \mu F}} = 172 \cdot 10^3\ \frac{\mbox{rad}}{\mbox{sec}}[/math]

[math]f=\frac{\omega_0}{2\pi} = 27.4\ \mbox{kHz}[/math]

And

[math]\mbox{Q} = \frac{1}{\mbox{R}} \sqrt{\frac{\mbox{L}}{\mbox{C}}} = 2.27[/math]

Measure the Gain [math]\equiv \frac{V_{out}}{V_{in}}[/math] as a function of frequency. (25 pnts)

Compare the measured and theoretical values of the resonance frequency ([math]\omega_{L}[/math]) (10 pnts)

Let's the plot the data from table above:

And let's zoom the graph above at resonance frequency:

So the experimentally measured resonance frequency is

[math]f = 27.7\ \mbox{kHz}[/math]

And the predicted value of resonance frequency is

[math]f = 27.4\ \mbox{kHz}[/math]

The error is:

[math]Error = \left| \frac{f_{exp} - f_{theor}}{f_{theor}} \right| = \left| \frac{27.7 - 27.4}{27.4} \right|= 1.09\ %[/math]

The error is small so I was lucky

Questions

1.Is there a value of [math]R[/math] in which [math]V_{out} \approx V_{in}[/math] at resonance. What is the value?(5 pnts)

The RLC cicuit

Questions

What is the current as [math]\nu \rightarrow \infty[/math]? (5 pnts)

Forest_Electronic_Instrumentation_and_Measurement

Go Back to All Lab Reports