Hi. So I'm reading about crystal radio and I finally managed to understand the true role of the LC circle(how since there is no losses at resonance the energy coming from the aerial just adds to the already existing one in the LC circle), but I don't understand how if the coil and capacitor are at resonance( they shift energy back and forth between them without theoretically any loss thus no need to be replenished and that's why LC circle at resonance appears as an infinite resistance to the rest of the circuit) is the LC circle able to power the speaker? The part where energy from the aerial is added in a loop that is not supposed to let anything in or out is weird too. Theoretically no current should leak out.

 

Forget 'no losses'. In any real circuit there will be losses.
A crystal radio will not power a speaker directly with no amplifier.
It will work a high impedance earphone or headphones but not the usual low impedance ones.

 

Hi. So I'm reading about crystal radio and I finally managed to understand the true role of the LC circle(how since there is no losses at resonance the energy coming from the aerial just adds to the already existing one in the LC circle), but I don't understand how if the coil and capacitor are at resonance( they shift energy back and forth between them without theoretically any loss thus no need to be replenished and that's why LC circle at resonance appears as an infinite resistance to the rest of the circuit) is the LC circle able to power the speaker? The part where energy from the aerial is added in a loop that is not supposed to let anything in or out is weird too. Theoretically no current should leak out.

its the easiest way to lower the Q and make the tuning much wider band.