Hi, I'm trying to model a sinusoidally driven harmonic oscillator using RLC circuits using LTspice IV. I get a reasonable result for the series RLC circuit, but not for the parallel circuit. Can anyone catch what I'm missing?
Ideally they should both give me the same result.
Attached files show circuits and AC analysis results.
In your image for the series connection, what voltage are you plotting? Is that the voltage across the resistor? I'm not really sure what you're trying to compare between the two.
Sorry, I'm trying to observe the motion of the mass of the harmonic oscillator:
in the series circuit - it's the current through the inductor
in the parallel circuit - it's the voltage across the capacitor
We could say the LC series and LC tank are nearly the same arrangement. Both have greater current flow at their resonant frequency. The difference is where you tap for the oscilloscope probe.
This simulation is a comparison. Notice where the scope traces tap the signal. The rolloff curves are nearly identical. Is this what you were aiming for?