Thunderbolt 1003

the Thunderbolt 1003 is a siren made by federal signal. It uses two solenoids that are attached to the throat of the horn. Each solenoid has a gate that closes off one row of ports on the stator. They are used to create alternating steady, alternating wail, pulsed steady, and pulsed wail signals, which can be used as a fire warning. Otherwise, it is identical to the 1000T, but used the 5/6 rotor only. Although the 4/5 port rotor is compatible, it was never offered originally. The 1003 entered production around 1959, and ceased in 1990. It is noteworthy that the 1003 was the last production unit ever built. The last sirens went to a township in Michigan.