9V/5A Regulated Power Supply Using LM7809 Voltage Regulator

9V/5A regulated Power Supply units (PSU) are a common but important part of everyday electronics. They commonly serve with test equipment in general & industrial applications. So, in this project, we are going to build a 9V/5A regulated Power Supply Using LM7809 Voltage Regulator IC.

LM7809 regulator IC is a common but an important part of 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. It offers features such as internal current limiting, thermal shut-down, and safe area protection, making it essentially indestructible.

Hardware Required

You will need the following parts to build this project

S.no	Component	Value	Qty
1.	Stepdown Transformer	230V/12V 5A 50Hz	3
2.	Regulator IC	LM7809	3
3.	PNP Power transistor	TIP2955	1
4.	10A Bridge Rectifier	50V PIV	3
5.	Capacitors	3300uF/50V, 0.33uF, 10uF	–
6.	Resistor	10hm/2W	1
7.	Breadboard	–	1
8.	Connecting Wires	–	–

Pin No.	Pin Name	Description
1	IN	A positive voltage is given as input to this pin.
2	GND	Common to both Input and Output.
3	OUT	Output regulated 9V is taken at this pin of the IC.

Circuit Diagram

Working Explanation

An input voltage of 230V is applied at the primary of the transformer which steps it down to 12V 5A through mutual induction of the primary & secondary windings while maintaining the frequency at 50Hz. After which the 12V AC signal goes through a 10A bridge rectifier which converts the AC signal into a rippling DC signal.

The DC signal then passes through smoothing capacitors C1 (3300uF) before passing on to an LM7809 voltage regulator IC which produces a constant 9V/5A DC signal at the output. Here, the TIP2955 transistor boosts the output voltage of the LM7809 IC. The output DC signal passes through a smoothing capacitor C2 (10uF) before moving on towards the output.

Applications

• DC power supplies are widely in use in low voltage applications such as charging batteries & automotive applications.
• It also serves in places such as aircraft and other places with low voltage, low current applications.