Single Chip Two-Tones Siren

Kids like the police or fire-brigade cars siren sound. This circuit can generate dual tone like Police or Fire-brigade cars siren sound. This circuit usually installed on battery powered cars, bicycles, and motorcycles. Not only that, but also can be installed in models and other games. Here is the schematic diagram of the circuit:

Basically, this circuit utilize the IC1A and IC1B gates oscillation to reproduce the typical dual sound of Fire-brigade or police cars. When the P1 is pressed, the IC1C and IC1D start oscillate, the old siren sound increasing and slowly decreasing in frequency is regenerated. The output sound is produced by the loudspeaker. The period and tone of the sound oscillations depends on the value of C5, C2, C6, C1 and/or associated resistors. This circuit does not have power switch. [Circuit’s schematic diagram source: english.cxem.net]