12V & 5V Dual power supply Circuit

Dual power Supply Circuit

Power supply form the basic building block of any electronic circuits and therefore its important to familiarize the DC power supply circuit construction. The above given circuit illustrates a simple approach to construct a dual DC power supply of 5V and 12V from the 230V AC mains supply. The Voltage ranges 5V and 12V are widely used in all kinds of simple electronic circuits, so its meaningful to learn this simple construction. 


The above circuit obtains power from a 230V AC mains supply voltage and fed into a step down  transformer for transforming higher voltage supply to lower one. The transformer TR1 can be of 230V primary ,15V secondary and 1A step down transformer. The stepped down voltage can be fed into the bridge rectifier made of four 1N4004 diodes for the conversion of AC supply to DC one. 

IC regulator pinout

The output from the bridge rectifier was filtered by the capacitor C1 and C2 to offer a steady DC level to the input pins of the regulators used in the above circuit. The DC voltage is then fed in to the IC 7805 which is a 5V regulator and also to the IC 7812 which was a 12V regulator. The output obtained from the 7805 & 7012 are 5V and 12V respectively. A LED D5 was connected through the current limiting resistor R1 for indicate the state of the device.

This kind of circuits are highly useful where two dual range of DC voltages are used to power the operation of a circuit. Varying the voltage regulator IC ‘s 7805 or 7812 with 7806 and 7808 to obtain 6V and 8V as output. But each IC have minimum and maximum voltage requirements, so make sure you build in such a way to meet the requirements. 

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Frank Donald

Frank Donald

Junior Network Engineer at Tata Communications
Frank Donald is an Electronics and Communication Engineer who loves building stuff in his free time. Video games, blogging and programming are the things he loves most
Frank Donald

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47 Comments on "12V & 5V Dual power supply Circuit"

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Thank you for this circuit. I’ll be testing it in the lab.

One mistake that you’ve made in your PCB layout is of the power source terminals. The negative terminal is not connected correctly. It should be between diodes 2 and 4.


is it provide 1A

Mark Joseph

What if I use a step down transformer 220v – 12v 2amphere. What will be the effect if I use that components? Thanks


i made this circuit but, the problem is when i connect the load to the 5v output supply i get only 6V from the 12V outpit pin.

Kartik Sikka

Hi Frank
You have done an awesome work by providing us the schematic with PCB Design . Thank for that !!

There is one thing , I want to ask that can i add 7809 in b/w 7812 & 7809 , as i want to make Power Supply which could deliver all three outputs 12V,9V,5V


Please can I use a 230-12v 500mA transformer instead


i’am ask to my supervisor our project,he say the circuit is false,can u explain to me sir??


Will it be okay if i used LM317 instead of IC 7812?


can this supply feed 2A load?


I have an 18V 2A transformer. will it be ok?