+12V and -12V Dual Power Supply Circuit Power Supply Circuits

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In this tutorial, we are going to design a “Dual Mode Power Supply +12volt and -12volt”. The +12V and +12V Dual Power Supply Circuit work by converting AC into both +12 volts and -12 volts DC. This is the reason for its name “dual power supply”

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Hardware Components

The following components are required to make a Dual Power Supply Circuit

S.No	Component	Value	Qty
1.	Breadboard	–	1
2.	Voltage Regulator IC	7812, 7912	1
3.	Centre tapped Transformer	220v/12v	1
4.	Power Diodes	10A	4
5.	Electrolytic Capacitor	2200uF/25v	2
6.	Toggle Switch	–	1
7.	Load Resistor/Motor	–	1

LM7812 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of LM7812

LM7912 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of LM7912

Circuit Diagram

Construction

To construct a dual supply circuit, the first step is to convert 220v AC into 12v AC using Step Down Transformer. This can be done when the center-tapped transformer’s primary terminals are connected to a power supply.

Then, the center-tapped transformer is used to convert 12 volts AC into 12v DC by connecting it to the bridge rectifier circuit which can either be half bridge or full bridge. And at last, one just needs to filter out the ripples from the output when there’s an input of 12v and the output will be +12v and -12v DC. It is important to regulate the output or else, it will start fluctuating.

Working Explanation

The process includes the following steps

First, the step-down transformer is used to convert an AC supply of 220 volts to 12 volts.
Then, the rectifier circuit converts it into DC by using the ripples.
The ripples use a supply of 25 volts along with a 2200 microfarad capacitor.
The DC obtained by the output uses a voltage regulator of IC 7812 and IC7912 which is used to obtain the output of +12 volts and -12 volts.