Nowadays, almost all electronic devices include a circuit that converts AC supply into DC supply. The section of equipment that converts AC to DC is a DC power supply. In general, at the input of a DC power supply, there is a power transformer. After this, a bridge rectifier (a diode circuit) converts DC to AC and passes it through a smoothing filter which then goes through a voltage regulator circuit along with some capacitors in order to remove any residual noise or ripples. In this project, we are going to design a basic DC 5V power supply circuit using an LM7805 voltage regulator IC.
LM7805 regulator IC is a common but important part of many 5V power supply circuits available in the market today. It is a 5V three-terminal positive voltage regulator IC. The LM7805 IC has many features such as safe operating area protection, thermal shut down, and an internal current limiting which makes the IC very robust. Output currents up to 1A can be drawn from the IC with a proper heat sink.
Hardware Components:
The following components are required to make Power Supply Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Voltage regulator IC | LM7805 | 1 |
| 2. | Stepdown Transformer | 230V to 9V 2A 50Hz | 1 |
| 3. | Bridge Rectifier Diode | 2A | 1 |
| 4. | Electrolytic Capacitor | 470μF 50V | 1 |
| 5. | Ceramic Capacitor | 0.01μF | 2 |
| 6. | Breadboard | – | 1 |
| 7. | Connecting Wires | – | 1 |
LM7805 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM7805
Power Supply Circuit
Working Explanation
An input voltage of 230V is applied at the primary of the transformer which steps it down to 9V 2A through mutual induction of the primary & secondary windings while maintaining the frequency at 50Hz. After which the 9V AC signal goes through a bridge rectifier which converts the AC signal into a rippling DC signal.
The DC signal then passes through smoothing capacitors C1 & C2 before passing on to an LM7805 voltage regulator IC which produces a constant regulated 5V DC signal at the output. The DC signal then passes through capacitor C3 to remove any residual noise before going on towards the output.
Applications
- DC power supplies are widely in use in low voltage applications such as charging batteries, automotive applications, aircraft applications, and other low voltage, low current applications.
