IC 555 Timer Based Vibration Alarm Circuit

IC 555 Timer Based Vibration Alarm Circuit is any easy to make.

It senses vibration and gives sound and light alert.

This circuit is used in security systems, factory machines and anti-theft devices.

Main part is IC 555 timer which sends steady signal when sensor feels vibration.

Circuit Working:

Parts List:

This circuit uses IC 555 in monostable mode.

Vibration sensor connects to pin 2 trigger pin through resistor R3 and capacitor C2 which helps cut noise.

Pin 5 connects to ground with capacitor C1 for stability.

Output pin 3 connects to BC547 transistor base using resistor R2.

Transistors collector powers buzzer and LED.

No vibration with sensor stays inactive with pin 3 stays low and buzzer and LED stays OFF.

When sensor feels vibration it sends signal to pin 2 and IC gives high output for time set by R3 and C2.

High output turns ON the transistor, buzzer and LED turn on with alarm sound and light.

ON/OFF switch controls battery power.

With ON the circuit works and with OFF the power cuts and saves the battery.

After vibration stops and time ends the pin 3 goes low and buzzer and LED turns OFF.

Formulas and Calculations:

Formulas and Examples for IC 555 Vibration Alarm Circuit:

1. Pulse Time (T) for Monostable Mode:

T = 1.1 × R3 × C2

where,

• T is the pulse time with seconds
• R3 is the resistor in ohms
• C2 is the capacitor in farads

Example:

R3 = 1MΩ, C2 = 100µF

T = 1.1 × 1,000,000 × 0.0001 = 110 seconds

2. Transistor Base Current BC547:

Ib = (Vout – Vbe) / R2

where,

• Ib is the base current A
• Vout is the IC output for 9V
• Vbe is the base emitter voltage for 0.7V
• R2 is the resistor in ohms

Example:

Vout = 9V, Vbe = 0.7V, R2 = 100Ω

Ib = (9 – 0.7) / 100 = 0.083A or 83mA

3. LED Resistor Value:

R = (Vbattery – Vled) / Iled

where,

• R is the resistor in ohms
• Vbattery is the supply voltage for 9V
• Vled is the LED voltage for 2V
• Iled is the LED current for 0.02A

Example:

R = (9 – 2) / 0.02 = 350Ω

Use nearest standard value resistor like 330Ω or 360Ωs 330Ω or 360Ω.

How to Build:

To build a IC 555 Timer Based Vibration Alarm Circuit follow the below mentioned steps:

• Gather all parts as shown in the circuit diagram.
• Pin 1 of IC 555 connects to GND.
• Pin 2 connects between R4, vibration sensor and GND(in series.
• Pin 3 connects to base of Q1 transistor through R2.
• Pins 4 and 8 connects to +9V supply.
• Pin 5 connects to GND through C1.
• Pins 6 and 7 connects together through R3 and C2 where C2 anode goes to pin 6 and cathode to GND.
• Collector of Q1 connects to +9V through buzzer.
• Emitter of Q1 connects to GND.
• Between collector of Q1 and buzzer connects LED1 and R1 in series to +9V.
• Add ON/OFF switch between +9V battery and the rest of circuit.
• Negative of battery goes to GND.

Conclusion:

This IC 555 Timer Based Vibration Alarm Circuit is small, simple and works well.

It senses vibration, gives sound and light alert.

It is useful for security, factory use or any place needing vibration check.

The circuit needs few parts, easy to make with low cost and is quite reliable.