AC to DC 12V Regulated Power supply

Last Updated on March 16, 2024

In Many electronic projects output actuators or output device needs 12 volt regulated power supply like, LCD, Graphic LCD and DC geared motors. This Circuit brings Regulated 12 Volt DC from bridge rectifier and a IC7812, this circuit uses 100uF capacitor as a simple filter to remove large ac ripples form rectified DC, and the capacitor 0.1uF capacitor removes small size ac ripples from Regulated DC output.

This AC to DC 12V Regulated Power supply circuit use Bridge Rectifier made by four 1N4001 Diodes, you can use any bridge rectifier module like W10M, Positive Voltage Regulator LM7812 in a TO-220 Plastic Package. Handles input voltage up to 35V and power dissipation is 15W, gives output voltage between 11.5V to 12.5V with load regulation Current from 5mA to 1.5 Amp. Even though it can operate in 125ºC temperature, it is better to provide heat sink.

LM7812 Pinout

Circuit Diagram

Components List

S.No	Name	Quantity
1.	Diode 1N4001	4
2.	Capacitor 100uF & 0.1uF	each 1
3.	IC 7812	1

Note: Step down transformer is not illustrated in this circuit diagram.

Operation of Bridge Rectifier

The step down transformer reduces the High voltage AC into Low amplitude AC supply and that is also in SINE form (Positive and Negative cycles), during the positive cycle of the input signal terminal A is positive with respect to terminal B. Here the current flows through D1 diode and RL and then D3 diode finally it reaches the terminal B. During this cycle Diodes D2 and D4 are not conducting any current supply.

During the negative cycle of the input, terminal B is positive with respect to terminal A and now the current flows through D2 diode, RL  and D4 diode finally it reaches the terminal A. During this cycle diodes D1 and D3 are not conducting. Hence for both positive and negative cycles RL gets current flow so its called as full wave bridge rectifier.

The first wave represents the input voltage and then each diode output current and voltage plotted, finally the load current appeared on load resistor RL, when we use bridge rectifier we can get continuous load current and voltage.