5v power supply using 7805 regulator 

At the input section of every electronic device, the most important section always belongs to the power supply block, if it is a large or small circuit arrangement power supplies must have to work properly to get good working operation.

 

In this article we are going to design a proper power supply using 7805 regulators ICs, at the output, we get a 5v and 1.5 amps of current.

 

The regulators are the devices used to maintain the power supplyvoltage value in a constant limit, for almost every electronic device fluctuated voltage values are not apt for proper working, so removal of ripples will be a must thing.

 

Before going to power supply designs, we have to consider multiple steps to follow to get into designing a power supply circuit.

 

5v power supply using 7805 regulator
5v power supply using 7805 regulator

5v power supply using 7805 with design 

First of all, we need to consider, what all are the blocks included in a regulator power supply circuit.

The block diagram shows the blocks that need to attach to form a good circuit.

 

block diagram of dc power supply
block diagram of dc power supply

How to select the right transformer

 

12 volt 1 amp transformer
12 volt 1 amp transformer

At any power supply circuit, transformers are used to convert 220v AC to your desire level AC, step down transformer will be used for power supply applications.

When we consider this circuit voltage rating, we have to step down 220 v AC to 12v AC, and the current rating must at 1amps.

Safety measures are been a must thing, when we use components like a transformer, lowering of voltage range with the coils are the concept of the transformer.

 

power supply rectifier circuit

 

power supply rectifier circuit
power supply rectifier circuit

 

In a power supply circuit conversion of AC to DC is done with rectifier circuit, in the first section transformer step down 220 v AC to 12v AC diodes are used as the rectification component, for different connections such as full-wave and bridge rectifiers and also we had a second option using bridge IC with the specification of 1.5amps.

 

power supply filter circuit 

The rectifier in the power supply get converts AC power to DC power, but it is not enough for a pure DC, output from the rectifier is pulsating, and here is the importance of the capacitor filter circuit.

The capacitor can store +VE voltage in its plates and ground extra voltage rising, after the filtration process, pulsating DC become partially pure DC.

We have different types of filter circuits are available, especially using a capacitor, difference happening by the connections and usage of components.

In this circuit, we have to filter 5v DC power, so a lower value PI filter using a capacitor filter is used for filtration.

 

How to select the right regulator

 

When we wish to select an apt regulator component in a power supply circuit, we have multiple options to opt for, before going to the details, we need to know about the importance of a regulator in a circuit.

 

In a circuit, the regulator will be placed after rectifier and filter circuits, so the regulator has the role, which is to stabilize the voltage variation.

 

After the initial filtration, our DC output is partially filtered, but the DC signal still have the ripples in it, so this power supply is design to have a 5v DC output, that range of voltage must be achieved using different regulators, such as Zener diode, op-amp and IC-based in the linear power supply.

 

In this circuit, we opt for the 7805 regulators IC, because they had many advantages over other regulators.

 

lm7805 pinout

lm7805 pinout
lm7805 pinout

 

It is a three-terminal device, 1st input pin, 2nd ground, and 3rd output pin.

They are designed to have a fixed 5V DC output, which has a minimum of 7v input capacity and a maximum of 25v, also have a maximum operating current of 5amps.

 

Protection systems 

  • Internal thermal overload
  • Short circuit protection 
  • Overvoltage and current protection 

 

Applications 

  • Constant 5v regulated for microcontroller 
  • Adjustable regulated power supply
  • Current limiter circuits
  • Output polarity- reversal protection circuits

 

circuit diagram of 7805 voltage regulator

 

circuit diagram of 7805 voltage regulator
circuit diagram of 7805 voltage regulator

The circuit only having three components, 7805 IC and two capacitors at input and output.

So we have to take the input capacitor as C in and the output capacitor as C out.

The C in the capacitor is used for input inductance control and C out is for the stability of the circuit.

Both theses capacitors should have to connect closer to the terminal for effective working and ceramic type capacitors are apt for the circuit because they have a faster operation than electrolytic capacitors, also the size of the ceramic type is smaller than electrolyte, which will affect in decreasing of size of the whole circuit.

 

7805 adjustable regulator circuit

 

7805 adjustable regulator circuit
7805 adjustable regulator circuit

This diagram shows the basic circuit of the adjustable regulatorusing the 7805 IC, you have to control the power supply voltage using a variable resistor placed in the circuit.

 

The range of input voltage 7805 IC withstand will be 9v to 25v.

Using the voltage divider circuits R1 and R2, we have to adjust output voltage using a potentiometer R2 in the circuit.

 

5v Power supply using 7805 voltage regulator circuit

 

5v Power supply using 7805 voltage regulator circuit
5v Power supply using 7805 voltage regulator circuit

 

This diagram show here is the regulator power supply using the 7805 IC designed and tested, which can get the output of 5v.

 

5v power supply Circuit explanation and working 

The regulator power supply circuit has very few components, which have 4 sections to get 5v regulated output.

 

At input we have a transformer section to step-down 220v AC to 12 v AC, before that we have a rectifier section, for the conversion process, we need to convert 12v AC to 12 v DC, this duty is done with the bridge rectifier circuit.

 

After the rectification process, the signal has ripples, also known as pulsating DC, so initially, we have to use a capacitor filter circuit to remove the AC components from the signal.

 

After the filtration process signal is partially filtered, at the end we have regulator component 7805 IC, which will stabilize the DC wave into the 5V range.

 

This is the whole working of the regulated circuit, in this circuit we had other options to implement for adjusting purpose and indication purpose.

 

Safety measures 

If you will wish to build this circuit, we have to follow safety instructions for safe circuit operating and arrangement.

 

At the transformer we need to put extra caution because they will be dealing with high voltage, so fuses and insulation will be implemented in the transformer section.

 

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