sentences:  The basic elements of the circuit are an inductance (tank coil) and a capacitance (tank capacitor) and an oscillator valve.Basic electrical principles dictate that if a voltage is applied to a circuit containing a capacitor and inductor the circuit will oscillate in much the same way as a swing which has been pushed.Using our swing as an analogy if we do not push again at the right time the swing will gradually stop this is the same with the oscillator.