Tone Detector circuit diagrams and explanation

The following circuit diagrams are tone detector circuit diagrams which also known as sound activated switch circuit. Actually, these circuits use micro-controller for switching because the circuits were designed for robot start up activation. But you can build switching module using relay.

Tone Detector diagram 1

Tone Detector diagram 2

Tone Detector diagram 3

Tone Detector diagram 4

Tone Detector diagram 5

Source: Sound activated switch for robot