Introduction: DIY RELAY MODULE

About: . I'am currently Doing my degree in Computer Science . I really love making things from scratch and loves Hiking .

Hi guys how are you ?

I hope you are fine !

Are you looking for making a relay board yourself , then your in right place.

today i will show you how to make a Diy relay module

that can be used any purpose . Even you can hookup with your Arduino or raspberry pi else use it for any project you needed a relay module. It costed me about 1$ (USD) to make one.

The reason i come up with this tutorial is last week i needed to make a project so fast(its a urgent project for my college) i needed a relay module to finish the last stage of the project, unfortunately i screwed . there is no relay module left in my garage . So, i went to a local store to buy one but there is no 5 volt or 6 volt relay module.But fortunately they have the relays , i bought so many(hope i can use like this situation in future :D) .then made one myself.

Its cheap and easy , you can save a little bit money by making these Diy relay module . At the same time you can use this relay module like a ordinary relay module. I made a single channel but you can make more on a same PCB.

for multiple channel like 2 or more , make copies of the same circuit in a single PCB.

So lets start making guys....!!!!


Now we need to collect some parts that we needed to make the Diy relay module.

NOTE : Most of the parts was lying around my home,I used to save little more ¢

here the list of all the parts you needed to do this project:


1. 5 volt relay(i used 6 volt because i need 6 volt relay)
2. BC548 transistor.
3. 100ohms resistor.
4. IN4001diode.
5. Screw terminals(3 pols , 2 nos)
6. LED(red or green,i used green here)
7. "5x3"cm Copper clad(optional if using general purpose PCB)
8. General purpose PCB(optional if use copper clad).
9. Breadboard and Jumpers.


1. Fritzing


1. Soldering iorn.
2. Soldering wire.
3. Soldering paste(optional,but recommended).
4. Hookup wire.

if you have any doubt in parts see the pictures above to clear the doubts or comment .


Now we have all the parts to make a Diy relay module.

Now we need to test the circuit diagram of the relay module on a breadboard.

don't skip this step , it is necessary to avoid mistakes when soldering into a PCB and check if it is works.

After all parts you collected lets go ahead to the next step.

Take a look the schematic diagram and PCB layouts.Then wire the circuit on a breadboard.Double check the schematics diagrams and Breadboard wiring for any wrong connection.

I gave the Pinouts diagram of BC548 transistor. carefull for wrong connections.

Now we need to check if it is working:

  1. first download the relay.ino file then open with your Arduino.
  2. connect the Vcc and GND pins of the relay module to the Arduino's 5 volt pin and gnd pin.
  3. then connect the relays input pin(the pin comes from the transistor's base pin) to the Arduino's digital pin 13.
  4. then upload the code.
  5. and check the relay is turning ON and OFF in a 1 second intervals(also the LED of relay module will turn ON and OFF)

if it is note working, suddenly turn OFF the Arduino .then check for any wrong connection existing,if have then solve that and re power the Arduino.

wooooww!!!!!! its works . Now we need to make the circuit on a General purpose pcb or custom pcb.


Now the time for make the circuit on a general PCB or a custom PCB.

this step is optional if you are decided to make the module on a custom PCB.

I really recommend make a custom pcb because it is more professional and perfect one.

However its your wish which way you need to make.

Here i will explain how to make the module on a general purpose PCB!.

  1. First take a general purpose PCB then clean well.
  2. After cleaning then rub some flux on it(optional,but recommended)
  3. them mount the components on the PCB then solder it.
  4. After solder everything then complete all traces(connections)using a Hookup wire.


We made the Diy relay module on a general purpose PCB.

Now check the relay works.


So, if you are like to make a custom PCB , we can go to the next step.


This step is optional if you made the module on a general purpose PCB!

I really recommend the Custom PCB,because the custom PCB is more clean and professional and less chance to short circuit.

i'am not made on custom pcb because i don't have time to make the PCB i said the situation before.

However lets go and make the PCB first!

watch the below video for how to etch a PCB yourself using toner transfer method.

After completing the video tutorial .

Download the fritzing project file down below( PCB design)

Then open the fritzing software(if not download and installed click here )

If you don't know how to use fritzing , click here(complete the tutorial , it almost three parts)

Then do the same you learned from the PCB ETCHING tutorial.

After etch the PCB . use a 0.8mm or 1.0mm drill bits to drill the holes in the PCB.

Then mount all the components and solder it.


we made the custom PCB for Diy relay module.

Now test the module.

I'am explained before in the step 2!

Step 5: DONE !!!

We successfully made our Diy relay module.

It would take me up to 20 minuites to make one . This is easy , inexpensive , cheap and also time saving(when you order one from online,take minimum a day) .

If you made one please click on I MADE IT button and also post the photo of your finished Diy relay module in comment section.

Step 6:



  • Planter Challenge

    Planter Challenge
  • Clocks Contest

    Clocks Contest
  • Casting Contest

    Casting Contest

We have a be nice policy.
Please be positive and constructive.




Can I use 6v realy as 5v actually I want oprtate 12v lock using raspberry pi 3 what should I do......?

is it ok with ac component using like a celling fan?

Hi, This project works fine for me when I used BC558 PNP transistor, but when I plug a NPN transistor like this one used in this project: the LED didn't blinking !!

Can someone tell why ?

Need to be careful with the current draw on the relay coil, and if using a number of them this can cause issues..

Also, nice to see a flyback diode in use, good 'ible, but could use a bit more detail on the circuit design, is the transistor npn or pnp.. Some will know, some won't, always worth adding in the extra few lines of explanation.. :)

Maybe even a couple of words on a snubber with inductive loads on the switched side of the relay ?

2 replies

Can you throw some light on snubber circuit. I want to control 230V 15A water pump/motor (inductive load, right?) with relay . Can you tell me how to go about snubber circuit or point me in right direction?
Thank you!

it is npn transistor you can see in breadboard schematics

looking to build an induction fired relay, got any ideas

there is usually an optocoupler on relay modules to isolate the signal from the coil spikes

I have made lots of relay driver circuits over the years. And if you want to drive them with even less current, use a "Darlington Pair" transistor setup and very little current will energize them. Good post and project.

3 replies

The relay will need just as much current to be energized but I guess you mean the current to trigger them. With the right darlington can even use yr finger to trigger them :-)

Yes, I am talking base bias to drive most any relay. I use Darlington Transistor configurations with water probes to turn pumps on and off. It takes so little current through the water to trigger a relay "on" via the Darlington Transistor pair, to engage the relay to start the pump. It is basically an extremely high gain amplifier setup. I just stated such a setup incase you don't have enough sing or source current capability from any microcontroller for such a driver setup.

As a matter of fact, have done that too for waterlevels. Plus wire in the water, base wire of 3 darlingtons in the water at various levels :-)

It never occurred to me to round the corners of the circuit board, but I like the result, it's not clunky- looking like a typical project and indeed does impart a more modular sense to it. ☺

2 replies

if you need to round PCB's edges, just use sand paper.

and protect yourself from th edust :-)

Great, I think everyone (who does electronics) should have build this at least once to learn. Often I see people just forget about the flyback diode.
Yet, I hope you dont mind that I point out that a completly ready made relay module only costs some 45 euro cents:

having said that, I still make such circuits myself if I want to integrate it on a larger board or dont fancy to wait 10 days for delivery.

I like the rounded corners. Maybe I shld start doing that myself as well