Factory Siren

Components :

                Resistor            : R1 6k8

                            : R2 100k

                            : R3 3k3

                            : R4 22k

                            : R5 1k

Trimpot                : RV 1k

Capacitor             : C1 4.7µF/10V

                            : C2 0.1µF/15V

Transistor             : Tr1 FCS 9013

                            : Tr2 FCS 9012

SCR                     : MEU 21

Speaker                8Ω 4 inch

This circuit is a siren tone generated by tone generator that generated by the two transistors TR1 and Tr2.
With about 500-100Hz frequency will produce an excellent sound sirens are used as signs began to come to work and marks a break from an office or factory.