555 timer project, police siren using 555 timer, 555 timer police siren, applications of 555 timer, Police siren circuit in Proteus, Proteus circuit of 555 timer project. Hey Geeks! Welcome to The Engineering Projects. We hope you are having a reproductive day. We know that sirens are the special sounds that are the symbol that something unusual is occurring or about to occur. You may have experienced the Siren of the Walkthrough Gates at the airport when a person ha ...