Audio Perimeter Monitor [Deleted]

Using a single cable such as speaker wire or doorbell cable, this circuit can be remotely positioned, for example, at the bottom of a garden or garage, and used to detect all sound in that area.

The cable can be buried in a hosepipe or duct and is concealed out of sight. The mic is an ordinary dynamic mic insert and should be housed in a waterproof enclosure with the rest of the circuit.

The mic output is amplified by the two transistors, the output is fed down the cable via the 220u...

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