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Design of Dual voltage power supply

In this article we will discuss how to design dual voltage power supply from single supply components. Circuit diagram and components rating of dual power supply are also presented. The dual output power supply is implemented and tested in ISIS Proteus and results are shown.

INTRODUCTION to dual voltage power supply

Power supply is an integral part of electronic circuits. Stable and accurate power supply ensures correct working of circuit as well as ensures long life of electronic equipment’s. Electronic equipment’s are very delicate. A slight overvoltage or disturbance in the supply can lead to serious problems in complex electronic circuits which are very difficult to determine and rectify. Most electronic components work on 5V. However there are considerable number of components which needs 12V to operate. Some operate on 6V. Since electronic arrangements are very small in size therefore multiple power supplies are impracticable in single electronic circuit. This article gives solution to this problem by presenting design of dual voltage power supply using single power supply arrangement.

Design and components of Dual power supply

The following components are used in construction of dual power supply

  • Capacitors 400uF, 25V
  • Diodes PIV=50V, 2 Ampere
  • Fuse 1 Ampere
  • Input supply 220V, 50Hz
  • Transformer 220V/12.6V, Center Tap
  • Switch

The purpose of transformer is to convert the high voltage into low voltage. For this particular application, the transformation ratio of transformer should be 220/12.6 = 17.46. In terms of coupling factor from primary to secondary its value would be 0.05. However it can be adjusted according to requirement. In order to get dual supply the transformer must be center tapped.

Four diodes are required to make a bridge. The bridge will convert the AC voltage to pulsating DC voltage for dual voltage power supply. The peak to peak voltage across diodes will be 25V so the rating considered for this application is 50V peak inverse voltage. To convert pulsating DC into smooth DC, soothing capacitors 0f 400uF will be used.

Switch is used for On/OFF while fuse is used for protection. The selection of fuse and all other components depends upon the current requirement of both supplies. If 500mA is current requirement for each supply output than total current on secondary side will be 1A. On primary side the current will be 50mA. So fuse of breaking current of 1A on primary side will be enough. If it is not available 2A at maximum can be used.

Circuit diagram of dual output power supply

Following figure shows the connection diagram for dual output power supply.

Diodes are arranged in the form of bridge to convert AC into DC. One output of higher voltage is taken from the bridge while other output is taken directly from the center tap.

dual output  power supply connection diagram

Simulation Results

Dual power supply is simulated in ISIS Proteus and the result is shown in the figure

As it can be seen that one terminal gives 12.2V as output while second terminal gives 6.14V.

About Syed Noman ud din

Syed Noman ud din is an Electrical Engineer and working in Industry from last 3 years. He writes technical articles for electrical and electronic engineers. He has also published several research publications in renowned international journals.

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