This circuit is the sound generator super siren, for use be alarm signal get by live frequency generator circuit that use , op-amp circuit. The principle works to are while still no press switch S1 will still have no the loud sound comes out from a loudspeaker SP1. When do pressure switch S1 then liberate C3 do something charge full until while press switch S1 and discharge go out. When liberate switch S1 come in at R7. Which perform in something limit current come in at 3 Non inverting legs of IC1a. By IC1, D1, D2, C1, C2 and R5 build be sound generator signal circuit then export come to way pin 6 of IC1a come to reach at pin 3 (Noninverting) of IC1b. By have R1 and R2 build be Dectector circuit. For do fining level has signal then signal to come out the way pin 7 of IC1b which will have flowing through comes in at pin B of Q1 for do something bias give Q1 bias. When Q1 work then make SP1 make a noise loud come out and make a noise poor loud C3 discharge be finished SP1 then stop make a noise loud.