A very simple police electronic siren can be built using electronic diagram below. This electronic siren uses electronic components and produce a Kojak character sound .
For this circuit required only two 555 timers and a few passive components. The first timer 555 produces a sound that can be adjusted with potentiometer P1 and excite a small speaker. Height sound is modulated by IC2 with low frequency signal. Modulation speed can be adjusted with the potentiometer P2. It thus produces a frequency modulated signal similar to that emitted by American police sirens.
The circuit can be supplied with a continuous supply voltage between 4.5 and 12 volts