Introduction
A Power Supply Circuit is one of the most important blocks in any electronic system. It converts electrical energy from one form to another, usually from high-voltage AC mains to low-voltage regulated DC suitable for electronic devices.
Almost every electronic project depends on a reliable power supply for proper operation.
Objective of the Project
The objectives of this project are:
- To convert AC voltage into DC voltage.
- To provide stable and regulated power to electronic circuits.
- To understand rectification, filtering, and regulation.
- To design a basic DC power supply.
Working Principle
A power supply circuit works in four main stages:
- Step-down Transformer
Reduces high AC voltage to a lower AC voltage. - Rectifier
Converts AC voltage into pulsating DC using diodes. - Filter
Removes ripples from DC voltage using capacitors. - Voltage Regulator
Maintains a constant output voltage.
Components Required
- Step-down Transformer (230V AC to 9V/12V AC)
- Bridge Rectifier (4 × 1N4007 diodes or rectifier IC)
- Filter Capacitor (1000µF – 2200µF)
- Voltage Regulator IC (7805 / 7812)
- Capacitors (0.1µF, 10µF)
- LED (Power Indicator)
- Resistor (220Ω)
- Breadboard / PCB
- Connecting wires
Circuit Diagram
Basic Power Supply Circuit
AC Mains
|
Transformer
|
Bridge Rectifier
|
Filter Capacitor
|
Voltage Regulator
|
Regulated DC Output
Circuit Explanation
- The transformer steps down AC voltage.
- The rectifier converts AC to DC.
- The filter capacitor smoothens the DC.
- The regulator provides constant output voltage.
- LED indicates power ON status.
Voltage Regulator IC Pins (7805)
Pin 1: Input
Pin 2: Ground
Pin 3: Output (5V)
Advantages
- Provides stable voltage
- Protects electronic components
- Simple and reliable design
- Low cost
Applications
- Electronic projects
- Embedded systems
- Microcontroller circuits
- Battery chargers
- Laboratory power supplies
Limitations
- Heat dissipation in linear regulators
- Lower efficiency compared to SMPS
- Limited output current
Conclusion
The Power Supply Circuit is the backbone of all electronic systems. This project helps students understand how raw electrical power is processed and regulated for safe use in electronic devices. It forms the foundation for advanced power management systems.
