Resonant frequency

Capacitors and inductors, when put in parallel, resonate to form small AC currents. The current is slowly lost due to ESR and wire resistance. The capacitor must first be charged up, then switched over to the inductor. Notice that it immediately begins to resonate at around 111 MHz. Change the inductance and capacitance values in small increments to see how the resonant frequency changes, and how long the circuit resonates. Also notice the phase shift in the voltage and current waveforms. Note that you may also have to adjust the simulation speed to see the resonance occuring. Note: The diode is a fly back diode to prevent inductive spikes. In order to prevent capacity being added to the circuit and the inductor resonating with the diode, the diode's junction capacitance must be zero or VERY close to zero. Otherwise the resonant frequency changes and the fly back diode does not do its job and begins to resonate.

published 10 years ago