For my electronics assignment, I carried out a lab test on a parallel RLC circuit. It was run in Proteus 8 and then carried out on a breadboard. An AC signal between 100hz and 20kHz was fed to the circuits and the inductor voltage was measured on an oscilloscope. The voltages across the inductor were much lower in the physical circuit, which is what I expected to happen at the beginning of the test. I put this down to the internal resistances of wires and components as well as the component tolerances, however when I went back into Proteus and amended the circuit to include the additional resistances, the inductor voltage at resonance was higher than the original Proteus circuit. I changed the values of the resistor, capacitor and inductor to values I found by testing the components in the physical circuit, and I also included resistances from the function generator and the inductor.


Graph of VL comparisons


Original RLC circuit in Proteus


Adjusted RLC circuit in Proteus

Could anyone explain why I might be seeing these results? I expected the adjusted circuit to be closer to the real one, and I am not certain why this might be.

Many thanks

 

Several things could be going on mostly revolving around component values and tolerances. An inductor with 7.32 Ω of parasitic resistance seems like it would detune a resonance peak such as your picture shows. What is the calculated impedance and frequency of the resonance peak?
The adjusted circuit shows a resonance peak at a lower frequency than the original, with maybe 250 mV higher peak voltage. None of this is too surprising. You have a voltage divider and you are changing the impedance of the bottom leg.