This is the simple electronic siren schematic, built using three ICs: CD4011
NAND gate logic, CD4066 Bilateral Switch and CD4046 Micro power
Phase-Locked Loop (PLL). Itis quite simple electronic siren design, low
cost and easy to assemble.
With this circuit we can create a
changing tone siren. The oscillator IC1A-B consists of two NAND gates
logic, oscillating at very low frequency. The oscillation leads the IC2,
which is an electronic bilateral switch, which opens and closes in the
rate of oscillation. When the switch is closed then the voltage charging
the capacitor C3 through the resistor R2. When the switch opens the IC2
C3 discharge through the R3.
The voltage which is charged by C3
regulates the VCO IC3 which is a PLL, so that we have at the output of a
changing sound. You can experiment with the values ??of resistors and
capacitors to change the sound of the siren. The R1, C1 time control
function, the R3, C3 control the change of sound and the R4, C2 control
the frequency of sound produced.
