Alarm sound fading-in circuit structure

The utility model provides an alarm sound fading-in circuit structure. When an acousto-optic alarm is started, the sound fades in in a certain period of time, and in the premise of ensuring that people don't get scared, the people can make the escape response in an instant and escape for the first time. The alarm sound fading-in circuit structure is simple and reliable in structure, and low in cost. The alarm sound fading-in circuit structure is composed of a switch drive circuit and a buzzer, and is characterized by comprising a charging delay circuit, a fading-in drive circuit and a controlled output circuit, wherein the output end of the charging delay circuit is respectively connected with the input ends of the fading-in drive circuit and the switch drive circuit, and the output ends of the fading-in drive circuit and the switch drive circuit are respectively connected with the input end of the controlled output circuit, and the output end of the controlled output circuit is connected with the input end o