The Thunderbolt is an electro-mechanical outdoor warning siren that was manufactured by Federal Signal Corporation from 1952 until its production ended in 1990. It is a unidirectional, rotating siren with a large square-shaped horn, and can come in various colors, usually yellow, by request.
History
The Thunderbolt siren was developed between 1951 and 1990. It was the first outdoor siren to be used with a blower to force air into the rotor. The blower increases the siren volume by 50 decibels. Many Thunderbolts are in private and legal possession.