(a) (b)(c)
(d)(e)
Figure 43.1: Construction of a crystal radio receiver. (a) Tuned LC circuit. (b) Addition of an antenna and
ground to drive the LC circuit. (c) Addition of a diode to rectify the signal and extract the audio. (d) Adding
headphones completes the radio circuit — the headphones convert the electrical signal from the diode to
sound. (e) Making the inductor or capacitor variable allows the radio circuit to tune different stations. Shown
here is a variable inductor.