How to Design a 5V DC Power Supply Easily

Power Supply Unit (PSU) is a vital part in any electronic product design.

Most Household electronic products such as Mobile Chargers, Bluetooth Speakers, Power Banks, Smart Watches etc requires a Power Supply circuit that could convert the AC mains supply to 5V DC to operate them.

In this Project we’ll build a similar AC to DC power supply circuit with 10W power rating.

That’s our Circuit will convert the 220V AC mains to 5V and supply a maximum output upto 2A.

This power Evaluation should be sufficient to power most electronic products running on 5V.

Also 5V 2A SMPS circuit is very well known in electronics since there are lots of microcontrollers which operates on 5V.

The idea of The project is to maintain the construct as simple as possible, so we will design the whole circuit above a dotted plank (perf board) and will even construct our own transformer so that anyone could replicate this design or construct similar ones.

Excited Right! So lets get started.

Formerly We also have built a 12V 15W SMPS circuit utilizing a PCB, so individuals who are interested in how to design a PCB for a PSU project (power supply unit) can assess that also.

The design Of 5V DC power distribution

The layout Of any circuit begins with a well made general block diagram.

It helps us To design the sections of the circuit separately and then at the end put them together to get a whole circuit, prepared for use.

The overall Block diagram for this job is provided below.

It’s very simple.

It has the Following four chief sub-blocks.

  • The Transformer
  • The Rectifier Circuit
  • The Filter
  • The Regulator

First, I Will clarify each block in general and then we will go for designing.

I think you Need to comprehend which block is doing exactly what first.

Block Diagrame of 5V Dc power distribution

Thus, let’s Try to comprehend each section one by one.

The input transformer

A Transformer is a device that can step up or step down voltage levels, after the law of conversation of energy.

The Question is, why we want it in our supply design?

Well, Depending on your state, AC coming into your house has the voltage level of 220/120 V.

We need the Input transformer to step the incoming AC to our required lower-level i.e. Close to 5V (AC).

This reduced Level is further employed by additional blocks to acquire the essential 5V DC.

A Transformer is a device that’s used to step up or step down the AC voltages level, keeping the input and outside electricity the same.

Be Mindful When playing this device.

As you are Employing the main supply voltage which could be too dangerous.

Never touch Any of the terminals with bare hands or with bad instruments.

Have a good And decent non-contact voltage tester, and utilize it to constantly be certain of which line is the live wire coming into the transformer.

The rectifier circuit

If you are Believing the transformer just stepped down the voltage to 5V DC.

I’m sorry, You’re incorrect like after I had been.

The Stepped-down voltage remains AC.

To convert It into DC, you want a fantastic rectifier circuit.

A rectifier Circuit is the combination of diodes arranged in such a manner that converts AC to DC voltage.

Without the Rectifier circuit, so it isn’t possible to have the mandatory output 5V DC voltage.

This Circuit comes in fine integrated packages or you may make it with four diodes as well.

You may See how we design it in later segments.

Basically, There are two types of this rectifier circuit; half-wave and full-wave.

But, The one that we’re considering is a full rectifier, since it is more energy-efficient than the initial one.

The filter

Nothing is Perfect in technical electronics.

The Rectifier circuit converts the incoming AC to DC but unluckily it doesn’t make it a pure DC.

The output signal Of the rectifier is pulsating and is called pulsating DC.

This Pulsating DC isn’t considered good to electricity sensitive devices.

So, the Rectified DC isn’t too clean and has ripples.

It’s the job Of the filter to filter out these ripples and to make the voltage harmonious for regulation.

A capacitor Filter is used when we will need to convert a pulsating DC into pure or to remove distortion from signal

A rule of Thumb is DC voltage must have greater than 10 per cent ripples to be controlled perfectly.

The best Filter in our case is the capacitor.

You will Have heard, a capacitor is charge keeping device.

But In fact, it can be best utilized as a filter.

It’s the Most inexpensive filter for our fundamental 5V power supply design.

The regulator

A regulator Is the linear integrated circuit use to provide a regulated constant output voltage.

Voltage Regulation is very important because we do not require a change in output voltage once the load varies.

An outcome Voltage independent of the load is obviously demanded.

The Regulator IC not merely makes the output voltage independent of varying loads, but also from line voltage changes.

A regulator Is your integrated circuit utilized to give a constant output voltage regardless of input voltage changes.

I hope you Have developed some fundamental theories of electricity supply design.

Let’s go further with the actual circuit Diagram for our specific 5V DC power supply layout.

Circuit Diagram of 5V DC power source

Below is The circuit diagram for the stated project.

You get the Main supply; voltage and frequency can ride on your nation, fuse; to safeguard the circuit, transformer, rectifier, capacitor filter, and an LED indicator, and the regulator IC.

Design 5V 500mA power distribution

The block Diagram is employed in NI Multisim software, good simulation applications for students and electronics novices.

I encourage Spent a while playing it.

Now, let Get into the actual layout.

Step by Step Method to Create 5V DC Power Supply

Here is the Deal, we’ll design each section first, then put together each of them to have our DC power source ready to power up our projects.

So let’s Get started step by step.

You’re Believing, I’d start the design explanation in the transformer but it isn’t the situation.

A Transformer is not selected at the very first.

#1: The Choice of regulator IC

The Choice of a regulator IC depends on your output voltage.

In our Case, we’re designing for the 5V output voltage, so we’ll select the LM7805 linear regulator IC.

From the Design process, the following issue is, we must know the voltage, current and power ratings of the selected regulator IC.

This is Done by using the datasheet of this regulator IC.

The Following would be the datasheet provided ratings, and pin diagram for LM7805.

Design 5V Power supply

The Datasheet of 7805 also prescribes to utilize a 0.1μF capacitor at the output side to avoid passing changes in the voltages due to changes in loading.

And a 0.1μF In the trunk of the regulator to avoid ripples when the filtering is far from the regulator.

Just for Extra knowledge, for positive ion output, we use LM78XX.

XX Indicates the value of output signal and 78 suggests positive output.

For Negative voltage output usage LM79XX, 79 suggests negative voltage and XX indicates the value of output.

#2: The Selection of transformer

The right Transformer selection means saving a great deal of cash.

We got to Understand, the minimal input to our selected regulator IC is 7V (See above datasheet values).

So, we need A transformer to step down the main AC to this value.

But, Between the ruler and secondary side of the transformer, there is a diode bridge rectifier too.

The Rectifier has its voltage drop across it i.e.1.4V.

We need to Compensate for this respect as well.

transformer and transformer symbol

So mathematically:

V_secondary=7V+1.4V \\ \\ V_secondary=8.4V(Peak value)

This means We should choose the transformer with a secondary voltage value equal to 9V or 10% more than 9V.

From these Points, for 5V DC power supply layout, we can select a transformer of current rating 1A along with a secondary voltage of 9V.

Why 1A Present? Because the regulator IC has a current rating of 1A, meaning that we cannot pass more present then this value.

Selecting a Transformer with the present score over this will cost additional cash.

And we Do not need it.

#3: The Choice of diodes for bridge

You see The circuit diagram, the rectifier circuit is produced by arranging diodes in some layouts.

To make Rectifier we must select appropriate diodes for this.

When Selecting a diode for the bridge circuit.

Keep in Mind the output load current, and maximum peak secondary voltage of the transformer i-e 9V in our case.

rectifier Circuit with symbol

Instead of Individual diodes, you may also use one individual bridge which arrives in an IC package.

However, I don’t Want you to use here, just for the purpose of learning and playing with individual diodes.

The Chosen diode must have the current rating more than the load current (i.e.

in this Situation is 500mA).

And summit Reverse voltage (PIV) over summit secondary transformer voltage

We select IN4001 diode because it’s the current rating of 1A more than our desire rating, and peak reverse voltage of 50V.

Peak Reverse voltage is the voltage that a diode can sustain if it is reverse biased.

#4: The Selection of smoothing capacitor and calculations

Things we Have to keep in mind while selecting a proper capacitor filter are, its endurance, power rating, and capacitance value.

The voltage Rating is calculated in the secondary voltage of a transformer.

The principle of Thumb is, the capacitor voltage rating should be at least 20 percent more than the secondary voltage.

So, if the Secondary voltage is 13 V (Peak significance for 9V), then your capacitor voltage rating must be at least 50V. capacitors For fundamental electronics

Secondly, we Need to figure the proper capacitance value.

It depends Upon the output voltage and the output current.

To find the Appropriate value of capacitance, use the formula below:

C= \fracI_otwo \Pi fV_o Where,

Io = Load Present i.e.

500mA in Our design, Vo = Output voltage i.e.

In our situation 5V, f = Frequency i.e 50Hz

In our case:

C= \frac500mAtwo \occasions \Pi\times50\times5 =3.1847\times 10^-4

Frequency Is 50Hz because in our nation mains AC is 220 @ 50Hz.

You may have 120V @ 60Hz mains AC.

If so then Place the values accordingly.

By using Capacitor formula, the sensible standard value near the value i-e 3.1847E-4 is 470uF.

Another Important formulation is listed under.

This can Also be used to compute the capacitor value.

C= \frac2+(Rf)2(Rf)fR

In this Case, R is loading resistance.

Rf is the Ripple factor, which should be less than 10% for a fantastic design.

And with This, we nearly finished with a 5V power supply design.

#5: Making the electricity supply safe

Every Layout must have a safety feature to protect it from burning.

Similarly, Our easy supply has to have a one i.e. the input fuse.

The input Fuse will protect our supply in case of overloading.

fuse and Fuse symbol

For Example, our want load can handle 500mA.

If in case Our load starts to miss behave, there’s a prospect of burring of components.

The fuse Will protect our supply.

A rule of Thumb for choosing the fuse rating is, it must be at least 20 percent more than the load current.

The simple Electricity supply we designed has the capability to deliver 1A present, which in some situations you’ll be able to use it to get.

Should you Decide to use it to get these instances, then don’t forget to attach a heat sink to the regulator IC.

More Fun With electronics

Electronics Is much fun.

You got new Items to do all the time as soon as you step into the world of electronic equipment.

Should you Love making DIY electronics, appreciated this post, heard all of the design theories, and today are interested to create your own DIY electricity supply undertaking.

You want to Solder and play around with all the aforementioned elements, check it out, the Elenco power supply kit (Amazon Link), you’ll find it interesting.

Additionally, there Is an enjoyable book named Make Electronics: Learning through discovery (Amazon link), which is going to teach you a lot of cool electronics together with practices.

If you find This book interesting, give it a try you will learn a lot.

Conclusion

For me, if You’re an electronic hobbyist or beginner, learning some basic electronics, I would recommend you to design your lab power supply.

It will Help you learn electronics as well as give you the ideal lab power supply.

I predict it The ideal one because you will make it all yourself.

And I Cannot place it in words how much fun it would be to play with electronics in a safe atmosphere.

It is like Learning from performing

Please do Not define it to only 500mA supply.

It can be Your own 5V DC power source in overall with up to 500mA current capacity.

And this Was what I know how to design 5v dc power distribution.

Hopefully, It was some kind of assistance to you.

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