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

Unexpected panic-inducing situations can arise for various reasons, such as the intrusion of an unauthorized person into our home or a sudden deterioration in our health. The triggers for panic can be diverse and differ from one individual to another.

In such emergency scenarios, we may find ourselves unable to communicate with those in our vicinity. This article explores the construction of a straightforward panic alarm system designed to promptly alert others to our distressing situation.

## Panic Alarm Circuit Diagram

### Components Required

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

## Design

This circuit is assembled using cost-effective components, including the IC 555 timer, a buzzer, along with a handful of resistors and capacitors. Its design prioritizes reliability, utilizing straightforward and less sensitive hardware components such as the 555 timer, ceramic buzzer, capacitors, and so on.

Despite the absence of specific provisions to account for variable parameters, the circuit is inherently designed to be resilient and user-friendly. It features a single button for effortless operation during moments of panic, ensuring a hassle-free response to emergency situations.

## Working

The IC 555 operates in the Astable mode, where the frequency relies on the values of resistors R2 and R3, as well as capacitor C2. Specifically, the values are set as follows: R2 = 100KΩ, R3 = 22KΩ, and C2 = 10µF.

By plugging these values into the relevant formulas for the IC 555 in astable mode, we determine that the circuit’s operating frequency is 1 Hz. Further calculations using this frequency yield a time period of 1 second for the circuit. This indicates that the circuit exhibits a repeating on-off cycle with a duration of 1 second.

Upon analyzing the ON and OFF time durations of the aforementioned panic alarm circuit, it’s evident that the circuit remains active for approximately 0.845 seconds and then remains inactive for roughly 0.152 seconds.

In the absence of pressing the button, the circuit remains in a deactivated state, and the alarm remains silent. Despite continuous power supplied to the IC 555, the circuit only operates in astable mode when the IC is enabled. This activation occurs solely when a high voltage is applied to pin 4 of the 555 IC, putting it into an enabled state.

This activation is initiated only when the button is pressed. To enhance visibility and ease of use, a plastic shell could be added to the button. For the sake of demonstration, a simple buzzer has been connected to the output of the 555 IC.

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