3.3V DC Power Supply Using L78L33 IC

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This is another project of a power supply. Power supplies are known as convertors of one electrical energy into another. They are responsible for providing electric current to loads. In this circuit, we are making a 3.3V DC Power Supply Using L78L33 IC.

L78L33 IC is a three-terminal positive voltage regulator IC. L78L00 is a series of positive voltage regulator ICs with built-in features such as thermal shutdown, internal current limiting. Therefore they are perfect to use in a power supply circuit. Their output current is up to 100mA and their output voltage varies from IC to IC. They have short circuit safety and because of their internal circuitry, these ICs don’t need much external components which ends up saving you from spending a lot of money and complicated circuitry.

Hardware Components

S.no	Components	Value	Qty
1.	Step-down Transformer	230V/12V 200mA	1
2.	Voltage regulator IC	78L33	1
3.	Diode Bridge	1N4007	4
4.	Electrolytic Capacitor	470µF	1
5.	Ceramic Capacitor	100nF, 330nF	1, 1
6.	Connecting Wires	–	1
7.	Breadboard	–	1

Circuit Diagram

Working Explanation

Since the IC that we are using in this circuit has all the important circuitry built inside it, therefore, we don’t need a lot of external components. The mains voltage of 230V AC is stepped down to 12V AC through a transformer. This AC signal is converted into a DC signal through a bridge rectifier. Before going to the IC this DC signal is filtered from any noise through smoothing capacitors. The filtered 12V DC voltage is now converted into a variable 3.3V output. The output voltage coming from this circuit is also filtered for any residual noise through a 100nF capacitor. This circuit can provide up to 100mA of output current and is suitable for all the circuits which require 3 volts.