The ACA Allertor 125 is a discontinued electromechanical Civil defense siren

Civil defense siren

A civil defense siren is a mechanical or electronic device for generating sound to...

made by Alerting Communicators of America. It has a distinctive design with the chopper on the bottom horn and the noise also coming out of the top horn.

History

The ACA Allertor was designed around the early 1960s as a 125dB siren with a metal horn. It has had many changes throughout its production run, the most notable being the horn changed to fiberglass around 1968, then to a larger design, as seen in the video. The Allertor was a popular choice for various communities in the Midwest from the late 60's, to the late 70's, and served as one of ACA's most popular sirens during that time. The design was unique, as it used a top horn design, with the intake built into the horn, near the bottom of the siren head. Despite being an efficient design, it was expensive to build the fiberglass horn. The Allertor was finally discontinued around 1980, and replaced with the more-efficiently designed Penetrator 10. The Penetrator 10 used a bell horn and cone intake that was much cheaper to produce. Many communities used the Allertor for outdoor warning purposes, however, they are now becoming more uncommon, as they are slowly replaced by more modern sirens.