PANIC ALARM CIRCUIT

       Hello guys. This is a simple alarm circuit by using 555 timer IC in mono stable mode of operation. The components required are

• NE555 IC     
  
• A piezo-electric Buzer
  
• Resistors (Values are specified in the diagram)
• Capacitors(Values are specified in the diagram)
• Push button switch
  
• Power supply or 9V battery
  
• Breadboard or PCB
  

The circuit diagram is shown below

WORKING

                The working of the circuit is based on the mono-stable operation of the 555 timer. The circuit is in the disabled mode when the switch is not pressed. When the switch is pressed it operate in the mono-stable state only. The IC is enabled only when pin 4 of the 555 given a high voltage which happens only when the switch is pressed.