•  
  •  

Police Siren

This circuit produces a sound similar to the police siren.
It makes use of two 555 timer ICs used as astable multivibrators. The frequency is controlled by the pin 5 of the IC.
The first IC (left) is wired to work around 1Hz. The 47uF capacitor is charged and discharged periodically and the voltage across it gradually increases and decreases periodically.
This varying voltage modulates the frequency of the 2nd IC. This process repeats and what you hear is the sound remarkably similar to the police siren.

Two presets VR1 and VR2 are provided to vary the siren period of repetition and the tone of the siren.
By varying VR1 you can set how fast the siren changes from high freq. to low freq.
VR2 sets the siren frequency. Adjust VR1 and VR2 to suit your taste.

If there are any problems please contact webmaster@electronic-circuits-diagrams.com

Please share & like

YASKAWA JZNC-RK22 MOTHERBOARD,
$2100.0 YASKAWA JZNC-RK22 MOTHERBOARD, picture
Portable Voice Amplifier SHIDU Personal Speaker Microphone Headset Rechargeable
$44.63 Portable Voice Amplifier SHIDU Personal Speaker Microphone Headset Rechargeable picture
INLAND KOLLMORGEN PWM 115-20/35-953A 115 VDC 50 HZ AXIS DRIVE
$200.0 INLAND KOLLMORGEN PWM 115-20/35-953A  115 VDC 50 HZ AXIS DRIVE picture
FANUC A06B-6064-H332#H550 AC SPINDLE SERVO UNIT W A16B-2201-0440/05B TOP BOARD
$850.0 FANUC A06B-6064-H332#H550 AC SPINDLE SERVO UNIT W A16B-2201-0440/05B TOP BOARD picture
VICKERS BRD-4DS SERVO DRIVE W/ BRD-S 4S TOP BOARD
$150.0 VICKERS BRD-4DS SERVO DRIVE W/ BRD-S 4S TOP BOARD picture