What is the difference between electronic and mechanical sirens? Are there other types of sirens?
A. Over the past 50 years outdoor warning siren technology has drastically changed to meet the demands of the purpose and use of the equipment. Sirens were originally manufactured for civil defense purposes. During World War II, the most common use of sirens was for signaling the threat of an air raid. Due to the nature of this type of warning and the lack of technology available at the time, the use of commercial power was the most effective means of producing high-powered sound. An electro-mechanical siren is a fairly simple device. It consists of an electric motor that turns a fan called the “rotor” or “impeller”, spinning inside a slotted drum called the “stator”. However, over the years these sirens have evolved to combine the use of electronics to control the tonality of the moving parts in the form of timers, relays and radios thus rendering them reliable on technology. The first job of the rotor is as a centrifugal fan. It pulls air into the siren axially through the intake, an
