This is the circuit diagran of two tone electronic siren. The scheme is simple and easy to built, it based on two ICs with different task: produce audio signal and amplify the audio signal.
List of Components:
R1-R2-R3: 2.2KΩ
R4: 1KΩ
R5: 10K (potentiometer)
R6: 470Ω
C1 - C2: 10 uF
C3 - C4: 470 nF
C5: 10 uF
C6: 220 uF
IC1: Integrated Circuit TTL 7400
IC2: LM386
Z1: Zener 5 volts 1/2 watt
Speaker 8 Ω