Security & Saftey

Panic Alarm Circuit

In this project, I will show how to design and build a simple Panic Alarm Circuit using 555 Timer IC and a few other easily available components. This circuit can be used to activate an alarm in case of any emergencies.

Outline

  • Introduction
  • Panic Alarm Circuit Diagram
  • Components Required
  • Design
  • Working

Introduction

There can be any sudden situation of panic. It could be because of an intruder entering our house or bad health status. Situations can be many for panicking and may vary from person to person.

During such emergencies, we might be unable to intimate to the people around us. In this article we shall see how to make a simple panic alarm, which can help us to intimate others regarding our bad situation without any delay.

Panic Alarm Circuit Diagram

Panic Alarm Circuit

Components Required

  • 555 IC
  • Resistor – 1KΩ
  • Resistor – 22KΩ
  • Resistor – 100KΩ
  • Capacitor – 10µF
  • 9V Battery
  • Push Button
  • Mini Buzzer
  • Breadboard
  • Connecting Wires

Design

This circuit is made with a low cost hardware using IC 555 timer, buzzer, a few resistors and capacitors. It is made to be working reliably as it has simple to use and not so sensitive hardware like 555 timer, ceramic buzzer, capacitors, etc.

Although no exclusive arrangement is used to make any compensation for the variable parameters, the circuit by default is made to be robust and easy to use. It is very user friendly with a single button to be pressed to handle the panicking situation without any trouble.

Working

The IC 555 is used in the Astable mode with the frequency depending on the values of resistors R2, R3 and C2. The values of R2 = 100KΩ, R3 = 22KΩ and C2 = 10µF.

The following values are obtained by substituting the specified parameters in the relevant formulas for the IC 555 in astable mode. The circuit’s operating frequency is calculated to be 1 Hz. We acquire the time period of the circuit as 1 second by applying the frequency information to find the time period of the circuit. This indicates that the circuit has a 1 second on-off repeating time span.

After analyzing the ON and OFF time period of the panic alarm circuit given above, we find that the circuit will remain on for about 0.845 seconds and off for about 0.152 seconds.

When the button is not pressed, the circuit is in the deactivated mode, and the alarm will not sound. Despite the fact that the IC 555 will be powered all of the time, the circuit will only operate in the astable mode when the IC is activated. Only when pin 4 of the 555 IC is supplied a high voltage does the IC go into enable mode.

Only when the button is pressed does this happen. A plastic shell could be added to the button to improve visibility and accessibility. I’ve wired a simple Buzzer to the 555 IC’s output for demonstration purposes.

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