How to make a Relay Module ?

 How to make a Relay Module?

Introduction :-

When we talk about the electronics indirectly we talks about the controlling of physical world. Electronic devices are capable enough to control the physical world. Generally  we deals with the low voltages in electronic circuits but some time we need to control a huge amount of electricity to run or stop some electrical devices for example when we need to control the main power line from distribution board. Than in general electronic, directly  we have nothing to control this amount of power. So if we want to control this huge amount of power than we have operate a relay as switch of  that further control the main power line.

A Relay Module:- 

A relay module is a electronic device the operates on 10-12 Volts DC but have a capabilities to handle a huge amount of power to switch some kind of electrical devices such as electrical fan , bulb, motor or iron etc. This module can be made some generic electronic components. These components can easily arranged from local market or your own electronic inventory.

The circuit diagram of a relay module is shown in the figure below.

As we can see in the circuit diagram, the incoming signal is fed to the optocoupler IC 4N25 through 1 kilo ohm resistor and LED D1 that switches the internal transistor through photo technique. When this internal transitor get switched on than it further switched on the externel transistor that is BC547 . This BC547 now power on the relay coil with 12 VDC and relay get energied due to this the contacts of relay get switched from NC (Normally Closed) to NO (Normally Opened) and the power given to common pole start going through NO terminal.

Construction:- 

This module required very few generic components. The list components are.

Small Piece of Zero PCB

One 12VDC  Coil Relay (PCB Mountable)

One BC547 Transistor 

One 4N25 Optocoupler IC

Two 1 Kilo Ohm Resistor 1/4 Watts

One IN4007 Diode

One 3 mm LED

7 Male Header Pins  

Soldring Iron and Some Basic tools

Make a  suitable sized zero PCB, it will be better to have holes of approx 3mm at every corner of this PCB piece. These holes are used to fix the relay module . Now assemble and solder  the components as shown in the circuit diagram before .

After finishing the soldring process cut the extra long terminals of components with the help of wire cutter. Now lets check the relay module . To check the relay module folllow the steps given below-

1. Double check the correct ness of soldered circuit.

2. Check for any type of shorting of solder in between tracks.

3. Join the 12VDC to terminal.

4. Give approx 5 VDC to In terminal at input (Jack 1).

5. Check the connectvity between comman to NO terminals at output (Jack 2).

6. If connectivity found than your circuit is okey and ready to use.

This Relay Module can be use to operate a load upto a limit as mentioned on the relay body. When a incoming 5 VDC signal comes the LED glows. It indicates that the optocoupler is working fine at input side. 

If we use new and reliable components than this circuit can withstand for years long. 

So this was for now . We will meet again for another intersting blog. 

Kindly suggest in the comments section.

What is a Desktop Computer SMPS ?

What is a Desktop Computer SMPS ?

(Switched Mode Power Supply)

Introduction

Computer is an state of art device and made to do numerous tasks like calculations, printing, scanning, document making saving and lots of many more. To perform these tasks computer have lots of electronic parts too. These parts works in a sequence to handle the data or various signals. These devices or components need various voltages at various current levels. To meet their power requirements a desktop computer need various voltages at various current levels.  A desktop computer SMPS ( Switched Mode Power Supply) handles these power requirements. this types of power supply comes in some variants also like 250 Watt, 350 Watts or 450 Watts and so. In this blog we will discus about this power supply.

What is a SMPS ?

SMPS ( Switched Mode Power Supply) is a AC to DC converter that changes the AC 230 VDC to various DC voltages. These voltages are as follow.

          

             +12 Volts

            -12 Volts

             +5 Volts

             -5 Volts

           + 3.3 Volts

            -3.3 Volts

To connect these voltages to computer circuit called computer mother board we have two types of power connector . There are two types of power connector that connects SMPS to motherboard . Both connectors are shown in the picture in following . 

20 pin  connector was used in old PCs and 24 pin connector can be found in almost new PCs . The basic difference can be found in the picture. The incoming voltage of a SMPS is 110-230 VAC, and outputs are discussed earlier. So lets see how a SMPS do his job ?

Circuit diagram shown in the picture is a basic idea of a SMPS . SMPS use PWM signal to for controlling of volateg and current for output. The incoming  power is converted in the DC voltage directly by a bridge rectifier and than filters by a strong dc capacitor . The maximum AC part of the voltage is removed hare . After this DC voltage is switched at controlled speed by the switching circuit and fed it to the SMPS transformer through a powerful transistor. This transformer actually works like an regulator of the outputs . It transformed the  various voltages at his secondary windings. After this step voltages formed filterred and fed to the computer motherboard. On another important circuit take care of the regulation that is feedback circuit . It takes some voltage from the output and feed it to the switching circuit. 

The switching of this circuit depends upon the voltage level of the output. This whole circuit is placed in a metal cabinet. As it is a SMPS power supply so this need a starting trigger to starts it functionality so one trigger wire or power ON wire need ti connect with the ground wire. When we connect this SMPS with the motherboard than PC power switch do this job but when we need to run this power supply without any motherboard than we manually need to start the functionality . The method is shown in the picture below. This is the biggest power connector for motherboard it cannects all the DC power  to the mother board too. 

With this power connector we have another power connector that joins the DC power to the mother board. It is shown in the picture below. 

 Various connector ans their works

  SMPS has various connectors to connect output with the computer peripheral device like HDD ( Hard Disk Drive), ODD (Optical Disk Drive ) . These devices need two dc power as 

+12 VDC-------------Yellow Wire

+5 VDC -------------- Red Wire

Ground----------------- Two Black Wire.

These are the most common output connector that are used  to connect hard disk or a optical drive ( CD or DVD writers etc.

These connector can seen any modern computer that these are power connector for SATA device like Hard Disk or DVD writer etc. The Voltage for these device are same as discuss earlier .

Some we need power converter that connects old type of power connector the modern one. 

one SATA power converter connector is shown in the picture.