Home Security Alarm System Without Microcontrollers
This home security alarm system operates without microcontrollers, relying on basic electronic components like transistors, resistors, light-dependent resistors (LDRs), and buzzers.
Key Components & Their Roles
- Light-Dependent Resistor (LDR) – Detects changes in light levels, triggering the alarm when an intruder disrupts the light source.
- Transistor (NPN) – Acts as a switch, amplifying signals from the LDR.
- Resistor – Limits current flow to protect components.
- LED – Provides a visual indication when the alarm is triggered.
- Buzzer – Sounds an alarm when the system detects unauthorized entry.
- 9V Battery – Powers the circuit.
Working Principle
- The LDR detects ambient light levels.
- If an intruder blocks the light, the resistance of the LDR changes, triggering the transistor.
- The transistor activates the buzzer and LED, alerting users of unauthorized entry.
- The system resets automatically when normal light conditions are restored.
Wiring Connections
| Component | Connection |
|---|---|
| LDR | Connected to transistor base |
| Resistor | Limits current to transistor |
| Transistor Collector | Connected to buzzer and LED |
| Transistor Emitter | Connected to ground |
| 9V Battery | Powers the circuit |
Advantages of This System
✅ No Microcontroller Required – Simple and cost-effective.
✅ Instant Response – Detects intrusions immediately.
✅ Low Power Consumption – Operates efficiently with minimal energy.
✅ Easy to Build – Uses basic electronic components.
Leave a Reply