Wireless Radio Tuning
Turning a radio dial is really adjusting a capacitor, and this simulation makes that visible. Several stations broadcast at once; as you tune the LC circuit, only the station whose frequency matches the circuit's natural frequency comes through clearly while the others fade into the background.
How to use this simulation
- Turn the tuning dial to vary the capacitance
- Change the inductance of the coil
- Switch between the available broadcast stations
What to look for
- Signal strength peaks sharply as you sweep through each station's frequency
- Stations close together in frequency are harder to separate
- The resonance peak broadens as resistance increases, making tuning less selective
The physics behind it
A resonant LC circuit responds strongly only to signals near its natural frequency f = 1/(2Οβ(LC)). At resonance the circuit's impedance to that frequency is minimised, so that station's signal drives a large current while off-resonance signals barely register. Selectivity β how sharply the circuit rejects neighbours β depends on the circuit's resistance.