Laser Communicator WITHOUT Audio Output Transformer

If you’ve searched around for “How to build a laser communicator“, you probably stumbled across several examples that use the RadioShack Audio Output Transformer, Catalog #: 273-1380.  I’ve built one and it works great, but it’s roughly $3 just for the transformer and finding these things elsewhere is nearly impossible.  They also add unnecessary bulk to the transmitter and we can build it using much cheaper components!

Laser Communicator WITH Transformer

The transformer version works great.  The only problem is that the transformers are a bit pricy and you’re very limited on where you can buy them.  You might try searching for Audio Coupling Transformer, which essentially all that it is used for here is for the purpose of isolation and a 1:1 small audio transformer would work for that.

Here’s a few links that feature this transformer version:

MAKE Magazine –
Their Youtube Video for this can be found at –
RK2Production Youtube Tutorial –
Transmitting Audio Wirelessly Through Light –

The transmitter schematic for this design is as follows:
Laser Communicator With Transformer Schematic



Additional Notes:

Laser Pointers:
“Why did I not use a laser pointer?”
Because the laser modules are essentially the laser pointer stripped down to just what we need for this project.  There’s no trying to keep the button pressed down, etc. AND the laser is focusable, making it a better option for longer range transmitting.  Oh, and it costs much less.

However, if you want to use a laser pointer, you can find cheap ones in a variety of places.  The ones I found have both an LED light and laser pointer from WalMart for approx. $2.49 by the checkout registers.  I then found some at the local Dollar Tree for $1, which were a bit smaller than the ones I found at WalMart.

Laser Pointer from Walmart

WalMart Laser Pointer

Dollar Tree Laser Pointer

Dollar Tree Laser Pointer

Laser Pointers Compared

Laser Pointers Compared

Audio Output Transformer:
Scitoys also sells them at and it is included in their “Laser Voice Transmitter Kit“.

RadioShack Audio Output Transformer

RadioShack Audio Output Transformer

RadioShack Audio Output Transformer

RadioShack Audio Output Transformer

2 thoughts on “Laser Communicator WITHOUT Audio Output Transformer

  • January 21, 2014 at 3:37 AM

    Hey. I want to build the Laser Transmitter with Mono Input. Would you take a picture of the connected Laser Transmitter?

    • January 21, 2014 at 10:03 AM

      Hey Chris,
      I updated page 2 to include pictures of my transmitter ( I’m combining the stereo input into mono on it though. To use a mono input, you can eliminate the (2)10K resistors on the input and one of the 0.1uF capcacitors. Just compare the two schematics given and that’s basically the only difference besides the first uses a 10uF capacitor.


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