How to Send Sound Using a Laser

About: We are a group of Engineers, Tinkerers, Designers, Programers, and Nerds ! ---- and Since April 2011 We also have a Cupcake Maker
We've all heard of it, but most of us didn't know what it was all about, sending sound using the light channel? ... well technically .... yes... but not really. All you really are doing is changing the intensity of the light. This light hits a solar cell which creates energy out of the intensity of the light. And IN TURN it creates sound.

This project has so many different applications, from the whole "cable is to short to reach", now you have no limitations on how far you can transmit the sound, or the Wires all over the room problem. Use your imagination and figure additonal ones out :)

Sound from a speaker is really just energy at different levels that makes a speaker turn into sounds that we can hear.... we'll explain everything in a few minutes. Watch this video if you don't feel like reading or go to our next step.

Step 1: Getting the Supplies

Alright unless you want to make this a permanent project we recommend you use alligator clips. They will help you out in the long run.

So you will need several alligator clips

A laser pointer

an Altoids Can (optional)

A solar cell

an Audio Output Transformer

An Audio phone jack

and a battery pack

Easy to get enough at Ebay or your local Radio Shack

Step 2: Setting Up Your Laser

Alright this is a short one, Grab one of your Alligator clips and place them on the inside of your laser there is a small spring in there you will attach a black alligator clip to that. That.s your negative.

On the outside casing you will attach a red one, any where on the outside shell would work this will be your positive.

that's It here :) Nothing more to see

Step 3: Audio Output Transformer

Alright so next you need to get the Audio Output Transformer ready. using one of your head phone jacks go ahead and break into the cable and get the two strings out from the inside, your positive and the negative, polarity doesn't really matter on this so just separate both cables.

Using alligator clips  you will attach one of the cables to the Red strip on the Output receiver and the other end of your jack to the White Output receiver.

and... that's bout it for this step too :P  move along

Step 4: Getting Everything Together for the Transmitter

Okay you need to get a 4.5 volt battery source, since our battery holder holds 4 batteries we had to rig it up with a jumper cable to only allow 3 batteries to work. You can do this by adding 1 dead battery to the source, or by using a jumper cable to connect two terminals together a + and a - ...

Now once that is one, you will hook the positive battery terminal to the black terminal to your transformer, the negative terminal will go to the black wire coming out of your laser (the alligator attached to the spring) .

The Positive terminal of your laser (red alligator clip attached to the shell) will go to the green wire on your transformer.

The middle transformer cable is unused.

Step 5: The Receiver

The actual receiver is very simple, you need to attach the solar cell to an audio jack by again exposing the wires from the audio jack and attaching them to the positive and negative terminal in the solar cell.

This completes the whole system now just hook up the solar cell to the radio receiver and then attach the laser transmitter to your CD player and test for sound, light up the laser and aim it towards the solar cell.

Now if you want to make this a more permanent structure, attach everything using a soldering gun and place everything inside of the Altoids Can.

Step 6: Altoids Can Transmitter

So here we soldered everything together and we placed it inside of an Altoids can, we even added a switch to help us out so we don't have to press the button to send sound. if you watch the video, you can see it works great :) we really loved it!

Thanks for taking the time to read this :)



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    23 Discussions


    3 years ago

    Hey...Howz the output clarity ??? i'd be pretty disappointing if the sound clarity is there a way to increase the clarity?? like amplify the signal or something like that


    4 years ago on Introduction

    Very cool! Would it be possible to do this with video? Maybe with three solar panels and a red, white and yellow cable?


    6 years ago on Introduction

    When I was a kid I had a toy that would transmit my voice like this only there were 2 units, gun like, each with incandescent flashlight bulbs and an amplifier in each as well. It worked in the daytime but it worked way better at night. Wish i could remember what they were called...


    7 years ago on Introduction

    Great tutorial!

    However, I'm really stuck.

    I've done everything 6 times over and still I can't get any sound.

    I get sound before the transformer, I get sound after the transformer, beyond that - nada!

    I've eliminated the solar cell and replaced it with another one, still nothing.

    I've replaced the laser with an LED and it works - Kind of!
    It's intermittent like it's 'buffering'.
    The laser doesn't work at all.

    Any ideas please anyone?
    Thanks very much


    8 years ago on Introduction

    So simple. I'm surprised a solar cell is sensitive enough to act as a reciever like that.

    What's the sound quality like? Is there a lot of degradation?

    1 reply

    Just made it: sound quality's fine but it's really quiet so you can't use headphones to hear to the sound


    7 years ago on Introduction

    Wow! This is so cool. I just finished making this, it's so amazing that you can do that with a laser! Great Job! If any one doesn't want to rig the battery pack or have to buy a new one, find an old rock band guitar, and get a soldering iron and melt the plastic around it and you can get the on/off switch with it and it works (that's what I did)


    Reply 8 years ago on Introduction

    Yes you can..(and is also cheaper)..However, you need to connect it to a power source such as a battery.(+ve pole of battery connects to one leg of LDR while the other connects to you stereo plug..-ve pole of battery connects to stereo plug...) I did the same thing a while ago and it works just fine except this 1 is way easier than the 1 I did.
    good luck... :)


    8 years ago on Introduction

    Instead of just telling us how to do it, you should teach people how it actually works. I get the basics but can you explain the purpose of the audio transformer.

    1 reply

    Reply 8 years ago on Introduction

    Also, I'm having trouble finding info about sending data over FSO, if you know anything about that, I'd love to hear it.


    8 years ago on Introduction

    quick before i go to radio shack to start this project...Where is the how is the music being and for that matter how do you chose what music is going to be transformed in the first place?

    3 replies

    Hook it up to a CD player or your phone or anything like that. (The laser part is hooked up to the CD player thats why you have to put on the head phone jack)

    we know it's an Audio Transformer, however when you add the laser, the transformer, battery, and headphone jack, it becomes a transmitter because now you are using the transformer and the additional tools to transmit the sound. Get it?