Review on Taidacent Voice-Activated Delay Switch 12V Sound Detection Relay Module | Sound Sensor Module with Voice Alarm by Dave Brummet

The device is well designed and documented. It worked right away, with a delay of about 1.5 seconds after triggering, and the microphone sensitivity was about right too. This is fortunate as the potentiometers are small 1 turn potentiometers and I found them quite finicky to return to reasonable settings later on. If you're not sure what it's doing, it has a small microphone connected to a comparator. When the tone exceeds a predetermined level, the comparator turns off and again starts a timer circuit that drives the relay. At this point, the SPDT relay closes (or opens, depending on the circuit selected) for a set period of time. The sound trigger is simply amplitude based. it can be a hand clapping, a voice, the noise of a robber, etc. So there are two settings (potentiometers): one for the volume, one for the relay switch-on time.