Sound Activated / Sound Operated Circuits

Alternative ultrasonic-whistle electronic circuit diagram schematic. Emits high pitch frequency in the 11-22 kHz range, which can be heard by dogs and other small insects.

An electronic circuit that uses a regular 2-inch speaker to detect for low frequency vibrations in the ground (such as those cause by a deer or human walking), and sounds an alarm.

This super cool circuit behaves as a clapper-switch. You clap and the circuit turns on. Clap and it turns off. Great as a light clap switch.