Introduction
Every electronic device requires a DC input supply to power its circuit. Primarily, the DC power supplies are employed to transforms the AC power into DC power. Hence it generates a more convenient voltage to the output device. Also, the circuits of power supplies have almost four stages. At the first stage, there is a transformer, then there is a rectifier circuit, after that, filter and at the final stage, there is the voltage regulator. To understand the working of all these stages, in this tutorial, we are going to make a 9 Volt Power Supply using an LM7809 Voltage Regulator.
The circuit uses a 16V transformer to step down the voltage. Diodes are there to make the rectifiers. Capacitors are employed as filters. And, voltage regulator IC is adopted to protect the circuit and control the circuit. Here in this circuit, we have used LM809 voltage regulator IC. Since IC has just 3 pins, therefore easy to handle.

Hardware Components
The following components are required to make a 9V Power Supply Circuit
S.no | Component | Value | Qty |
---|---|---|---|
1. | PCB | – | 1 |
2. | Transformer | 16V | 1 |
3. | Diodes | 1N4007 | 4 |
4. | Electrolytic Capacitor | 470uf | 1 |
5. | Voltage Regulator IC | 7809 | 1 |
6. | Ceramic Capacitor | 0.01uf | 2 |
LM7809 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of LM7809
9V Power Supply Circuit

Working Explanation
In this circuit of 9 Volt Power Supply, the transformer in the circuit is used to convert the supplied voltage to the voltage that is needed. The diodes together make the rectifier circuit that converts the alternating current into direct current. Then the capacitors are used as filters that filtered out the ripples and give smoothness to the voltage. At the final stage, the regulator IC is wired to adjust and controls the output voltage.

Application and Uses
The power supply circuit is utilized in every electronic device such as:
- Firstly, in computers.
- Further, In electrical vehicles
- Also, in automation devices like motors, pumps, assembly lines, etc.
- Moreover, in medical devices like ventilators, infusion pumps, etc.