About: I'm a guy who loves to play with technology .....

Hello guys, after a long time I am back again to share a new and simple project. In this project I will show you how you can transmit data signals from one place to another through Light. Sending data over light isn't a new concept but recently it gained a lot of attention after the introduction of LIFI . In this tutorialwewill transmit simple data like Binary and Audio through LEDs and Laser.

So lets get started....


  1. BD139 Transistor. (Any NPN transistor will work. 2N2222 can be used)
  2. LED orLaser.
  3. 10uF & 100uF capacitor.
  4. Two 1k Ohm resistor.
  5. 50 and 100 Ohm resistors each.
  6. Switch.
  7. 10k Ohm Potentiometer.
  8. Earphone Jack.
  9. Breadboard
  10. Arduino (Optional. If you want to experiment with different data.)

For Receiver:-

NOTE:- If you have computer speakers you don't need to make a Receiver.But you will need Solar cell or LDR to receiver Light signals.

  1. Two BC547 /2N2222 transistors.
  2. LDRorsolar Cell
  3. 1k and 10k Ohm Resistors each.
  4. 1uf Capacitor.
  5. Speaker.

I have provided Links to the components but you can buy these from local electronic's store.


The setup is simple. Just follow the circuit diagram I have provided. For a reference check the Breadboard Layout. Here I have usedBD139 transistor but you can use any general purpose NPN transistor, just take note of the Pin out diagram of it. Also power the circuit with 5v - 7v depending on what you are using ( Laser or single LED).

Once the circuit is ready. Power it up and see if the light glows. If it does then turn the potentiometer to check if the intensity of light changes. If it does, Everything is fine and you can proceed to the next step.

If it does not work check the connections and polarity of the transistor.


Just in case you don't have a Computer speaker or you just want to make this full "DIY Project", You can follow the circuit given above to make a simple audio-amp.

If you have a computer speaker things are pretty simple in this step. just use a Female Audio jack and connect it with two wires to a solar Cell or LDR and plug the speaker. that's all here.

Step 4: HOW TO USE IT ???

Once the Transmitter and Receiver are made just connect the earphone Jack to any music player or a mobile phone and play a song. Adjust the Potentiometer to dim the LED, You will notice it flickering. If it doesn't recheck the connections and try again. When it flickers it means the sound is been converted to digital signal and transmitted via light.

Now just place the solarcell or LDR near the LED and you will hear the music being played on the speakers. Adjust the brightness of the LED to get a more clearer sound. For long distance transmission use a laser.

Now that you have successfully transmitted audio, You can experiment with different type of data using Arduino. To connect it to an arduino just connect the GND pin of arduino to Ground and Input pin of capacitor to any Digital pin of arduino and set the pin to transmit data. But to decode these signals of arduino you will need another Arduino at receiving end. But that's for another Instructable. Till then try this and experiment more...

I hope the instructions are easy to understand. If you have any questions feel free to ask in the comments.



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    9 Discussions


    Question 2 days ago

    Hi Sir..!! i have successfully connected all the components and powered it on but the led just blinks once and goes off.... and then i tried powering on again but the same error occurs...... plz help me solve this problem...

    2 more answers

    If you have used same components and followed the instructions correctly such error should not occur, I cannot help without looking at your connections. I suggest you trouble shoot the circuit once again and if you cant find error. post some pics of your build so I can have a look at it.

    I'm sending some photos plz help me...


    sir i made the project but i am getting full of noisy signal and the sound was too low .How can i over come this to get a good communication medium...

    1 more answer

    Reduce the ambient light by making the room a bit dark. Then Adjust the Potentiometer slowly until you hear clear sound.

    Hey this project seems nice but I realised it and I have a little problem. When I see the Led flickering, and I put the solar cell just upon it, I can't hear any change of noise and just a rustle, do you have any idea of what could be the problem here ?
    Thanks for this

    1 more answer

    Try increasing the intensity of the light.

    Hey this looks like a really cool project and i wanna do it . Im still kind of learning so i would like to ask did u solder two wires the solar panel to connect with the speakers ? Also for the input through the earphone jack how do u connect to two wires.( I have these questions seeing the parts u suggested) Thanks and cool project!

    1 more answer

    I'm glad you liked the project. And yes I soldered the wires to solar panels.
    The earphone jack I used has 3 pins. you just have to connect one wire to ground and other to any 1 terminal. to identify the ground you can search google for earphone jacks pin diagram.