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 9V power supply circuit using an LM7809 voltage regulator IC.
LM7809 regulator IC is a common but important part of a much 9V power supply circuit. LM7809 is a 9V Voltage Regulator that restricts the voltage output to 9V and draws 9V regulated power supply. The LM7809 is the most common, as its regulated 9-volt supply provides a convenient power source for most TTL components.
Hardware Components
The following components are required to make a 9V Power Supply Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Breadboard | – | 1 |
| 2. | Connecting Wires | – | 1 |
| 3. | Voltage regulator IC | LM7809 | 1 |
| 4. | Stepdown Transformer | 230V to 16V 2A 50Hz, | 1 |
| 5. | Bridge Rectifier Diode | 2A | 1 |
| 6. | A heat sink (optional) | – | 1 |
| 7. | Electrolytic Capacitors | (470μF 50V) | 1 |
| 8. | Ceramic Capacitors | 0.01μF | 1 |
LM7809 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM7809
9V Power Supply Circuit
Working Explanation
An input voltage of 230V is applied at the primary of the transformer which steps it down to 16V 2A through mutual induction of the primary & secondary windings while maintaining the frequency at 50Hz. After which the 16V 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 LM7809 voltage regulator IC which produces a constant regulated 9V 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.
