Worked example: Trace an AM voice signal through an envelope detector. Step 1: The antenna receives an AM wave: carrier 1 MHz whose peaks rise and fall 300–3000 times per second following the voice. Step 2: The diode conducts only on positive half-cycles, so the output is a train of positive humps with the same envelope. Step 3: The RC filter charges quickly to each hump's peak through the diode, then discharges slowly through the resistor between humps. Choose RC so it follows 3 kHz voice wiggles but smooths out the 1 MHz carrier ripple. Step 4: The capacitor voltage now traces the voice waveform; a blocking capacitor removes the DC level, leaving clean audio for the speaker. Conclusion: three cheap components recover the message — but any noise spike also passes the diode, which is the price of AM's simplicity.