# [SOLVED]How component requirements are determined for power supply

#### Pushkar1

Joined Apr 5, 2021
416
I want to design a power supply to meet the following requirements,

Input Voltage : 12 V AC
Input current : 2 A
Output Voltage : 5 V DC
Output current : 1A DC.

I have seen many circuits on Google in which I see that I need the following components to make the power supply

Rectifier
capacitor filter
Regulator IC
Resistor ( current limiting)

At first need a rectifier in my power supply. There are three types of rectifiers half wave, full wave and bridge rectifier

How do we decide which rectifier required and why it should be used only

#### Audioguru again

Joined Oct 21, 2019
6,608
Simply learn about the differences (pros and cons) of half-wave vs full-wave then the cost and space of separate diodes vs a bridge rectifier.

A simple calculation shows that the fairly high input voltage causes the regulator to get hot and dissipate about 10W of heat.
Most voltage regulators need an output capacitor.

Joined Jul 18, 2013
28,510
I want to design a power supply to meet the following requirements,
How do we decide which rectifier required and why it should be used only
What is the PS used to serve?
Regulated or not?

#### dl324

Joined Mar 30, 2015
16,672
Welcome to AAC!
I want to design a power supply to meet the following requirements
Is this school work?

#### Pushkar1

Joined Apr 5, 2021
416
Welcome to AAC!

Is this school work?
No, This is not a school assignment

What is the PS used to serve?
Regulated or not?
Regulated , To power 5V Digital IC

Simply learn about the differences (pros and cons) of half-wave vs full-wave then the cost and space of separate diodes vs a bridge rectifier.
I guess Bridge rectifier is more efficient than others, if this is the case,
Then When half wave and full wave rectifier should be used in power supply ?

Last edited:

Joined Jul 18, 2013
28,510
Bridge rectifier IS a full wave rectifier and is the most efficient of the two for a P.S.

#### dl324

Joined Mar 30, 2015
16,672
Then When half wave and full wave rectifier should be used in power supply ?
Half wave would give up half of the transformer current. Does the secondary have a center tap?

#### Pushkar1

Joined Apr 5, 2021
416
Half wave would give up half of the transformer current. Does the secondary have a center tap?
Ohh I am sorry I gave the wrong information in my starting post. I have 12 V DC adapter and I want to convert 12 V DC into 5V DC @ 1 A current.

I understood that I need bridge rectifier IC or four diodes to make bridge rectifier circuit. I would like to use diodes. A lot of ratings diode avillable in the market and I have to choose diode according to my requirements.

When choosing a diode I must remember that it is perfect for my supply and it should not be damaged, Which rating of diode should I choose to make rectifier?

Joined Jul 18, 2013
28,510
If it is already DC, why do you need a bridge?
There are many all-in-one bridge rectifiers out there of different current ratings, also four 1n4007 would make a 1 amp bridge.
What are you using for a voltage regulator? IC7805?

#### BobaMosfet

Joined Jul 1, 2009
2,105
I want to design a power supply to meet the following requirements,

Input Voltage : 12 V AC
Input current : 2 A
Output Voltage : 5 V DC
Output current : 1A DC.

I have seen many circuits on Google in which I see that I need the following components to make the power supply

Rectifier
capacitor filter
Regulator IC
Resistor ( current limiting)

At first need a rectifier in my power supply. There are three types of rectifiers half wave, full wave and bridge rectifier

How do we decide which rectifier required and why it should be used only
Welcome to what it means to be an Electronics/Electrical Engineer. This is what we _do_. We take needs and determine the constraints and risk-factors, and then choose components that satisfy those constraints and risk factors.

Start here:

Title: Understanding Basic Electronics, 1st Ed.
Publisher: The American Radio Relay League
ISBN: 0-87259-398-3

#### djsfantasi

Joined Apr 11, 2010
9,151
Ohh I am sorry I gave the wrong information in my starting post. I have 12 V DC adapter and I want to convert 12 V DC into 5V DC @ 1 A current.

I understood that I need bridge rectifier IC or four diodes to make bridge rectifier circuit. I would like to use diodes. A lot of ratings diode avillable in the market and I have to choose diode according to my requirements.

When choosing a diode I must remember that it is perfect for my supply and it should not be damaged, Which rating of diode should I choose to make rectifier?
If your input and output are DC, then there is no need for any rectifier. A rectifier converts AC to DC.

A 7805 voltage regulator is the simplest solution. The data sheet shows the ancillary components needed - such as input and output capacitors.

Joined Jul 18, 2013
28,510
Here is the circuit I implied

#### dl324

Joined Mar 30, 2015
16,672
I understood that I need bridge rectifier IC or four diodes to make bridge rectifier circuit. I would like to use diodes. A lot of ratings diode avillable in the market and I have to choose diode according to my requirements.

When choosing a diode I must remember that it is perfect for my supply and it should not be damaged, Which rating of diode should I choose to make rectifier?
For your application, you don't need rectification.

With 12V in and 5V out at 1A, I'd use a switching regulator. Otherwise, you're going to dissipate 7W in the regulator at full load.

#### Dodgydave

Joined Jun 22, 2012
11,236
If you're dropping down from 12v to 5v, then use a 7805 regulator or better still use a buck regulator like lm2576.