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Monday, June 22, 2009

5V, 12V Regulated Power supply

5V, 12V Regulated Power supply
Regulated power supplies are commonly used in engineering projects. Power supply is food of any circuit. I would like to share 5V, 12V regulated power supply circuits which can be used for Embedded or Micro controller projects.

+5V SUPPLY UNIT
The circuit diagram of +5V is shown in the figure. +5V supply is obtained from the +5V supply unit for microcontroller and digital ICs. Initially 230 V AC supply is reduced to (0-9V) with the help of a step down transformer having a capacity of 500mA. Since the input voltage to the regulator IC should be more than its output voltage, transformer secondary voltage is 9V. This low voltage is rectified with the help of bridge rectifier. The ripples are minimized with the help of capacitor filter to get a smooth DC supply. The rating of the chosen capacitor filter is 1000µF.
The regulated DC voltage is obtained by using a regulator IC 7805. In the case of IC 7805, the unregulated DC voltage is applied to Pin 1, and the output is taken at Pin 3 and Pin 2 is grounded. Another capacitor filter of rating 10µF is connected at the output of regulator IC to eliminate the voltage oscillations at the output due to the large voltage oscillations at the input of the regulator.

+12V SUPPLY UNIT
The ±12 V supply required by the OP amps is provided by the 12V supply circuit arrangement. The circuit diagram of ±12V power supply unit is shown in figure. Initially 230 V AC supply is reduced to (15V-0-15V) with the help of a step down transformer having a capacity of 1A and the center tap of the transformer is grounded. This low voltage is rectified with the help off bridge rectifier. Since the input voltage to the regulator IC should be more than its output voltage, transformer secondary voltage is 15V-0-15V.The ripples are minimized with the help of capacitor filter to get a smooth DC supply. The rating of the chosen capacitor filter is 1000µF.
The regulated DC output voltage is obtained by using regulator ICs. For regulated +12V DC supply, IC 7812 is used and for regulated -12V DC supply, IC 7912 is used. In the case of IC 7812 the unregulated DC voltage is applied to Pin 1, and the output is taken at Pin 3 and Pin 2 is grounded. In the case of 7912 ,the unregulated DC voltage is applied to Pin 2, the output is taken at Pin 3 and Pin 1 is grounded. The pair of capacitors of 10µF is connected at the output as shown in figure to eliminate the voltage oscillations at the output due to the large voltage oscillations at the input of the regulator.

10 comments:

Anonymous said...

oh, come on, that's too simple!!

ArticIce(Juice)

Anonymous said...

i thought it was good. cheers :)

Kruthi said...

It helped me write my lab record! :P
Thanks a tonne! :)
-BE student.

Roberto said...

Do I need to put a heatsink for 500mA? How do I know if I need one?

Roberto said...

How do I know I need a heatsink? Do I need one for 500mA?
Regards,
Robert

piyush said...

i m going to make mobile charger to my mobile using 7805 amd a simple rectifier which a got form old charger.. thanks for idea. i hope it 'll working well.

Poovendhan E said...

Any body please help what if i use 1000uF,16v capacitor instead of 1000uF,25v as given here.......what change will it make?

Shuvojit Das said...

Nothing special will happen. both are approximate same in this purpose. @poovendhan

Shuvojit's recent blog : 5V Regulated Power Supply Circuit Diagram

Bejoe Cherian said...

will the above circuit work if the required current rating is the range of 4-5A?
and can i get 12v and 5v from the same circuit?

Yokara said...

You can not use the circuit for higher current (amps) ratings.

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