Category:Electromechanical Sirens

An electromechanical siren utilizes an electric motor to drive a spinning rotor, also known as a chopper, which is located inside a stationary stator. Typically, the rotor and stator contain an equal number of holes ("ports"). The vanes within the rotor direct air through these ports. As the rotor spins, the air is pushed through the ports and is chopped at a specific frequency, producing sound. The number of ports in the siren and the speed of the rotor both influence the pitch; the more ports present and the faster the rotor rotates, the higher the peak pitch of the siren.