Civil Defence Sirens #15

20/24 Thunderbolt 1003 Synth | Growl & Alert

7/10 Thunderbolt 1003 synth | High-low

8/12 Thunderbolt 1003 synth | High-low signal

Sentry 40V2T HI-LO Synth

If Thunderbolt 1003 would be 9/12 port | High-low signal

If Thunderbolt 1003 would be 6/12 port | Alert signal

If Mineola Thunderbolt would be 7/10 port

Thunderbolt 1003 with 8/10 port chopper and 6M Blower | Alert signal

if the 10/12 thunderbolt had a broken solenoid

Civil Defence Sirens #14

Сирены Гражданской Обороны #13 (Россия)

Civil Defence Sirens #12

electrical hazard sign #2

Civil Defence Sirens #11

Civil Defence Sirens #10

Civil Defence Sirens #9 (Harry O. Ricci)

Civil Defence Sirens #8 (Federal Signal)

Civil Defense Sirens #7 (Alerting Communicators of America)

Civil Defense Sirens #6

A.C.A. Hurricane 130 MKI/MKII old videos

Civil Defence Sirens #5

Most popular sirens in 1950's

Civil Defence Sirens #4

Ermish warning siren system

Model M all port ratios

Decot red arrow historical photos and all port ratios

Thunderbolts

Sterling machine company

Dillon Box Iron Works Co.