HFU HF Underground

Technical Topics => The RF Workbench => Topic started by: ThaDood on April 15, 2022, 1844 UTC

Title: Wanna' communicate, and broadcast, with light? It can be done!
Post by: ThaDood on April 15, 2022, 1844 UTC
I've experimented with IR and white light LED's. Even thought of this as a station STL. However, this is Line-Of-Sight, so snow fall, heavy rain, even birds, will block this.   http://www.modulatedlight.org/optical_comms/optical_index.html     and    https://sites.google.com/site/g3xbmqrp3/optical      All neat, and legal to do.
Title: Re: Wanna' communicate, and broadcast, with light? It can be done!
Post by: KaySeeks on June 11, 2022, 0146 UTC
When I was a young lad (maybe 12 years old), I had a 100-in-1 electronic project kit and got a bright idea.

They had a project in the accompanying book that was a simple audio amplifier. I used that amplifier to drive the LED in the kit and used the small speaker in the kit as the microphone input to the amplifier. It worked well enough and it was fun to watch the LED brightness go up and down with my voice. Later I hooked up the solar cell (or maybe the photodiode? I forget) as a detector to a second amplifier and a second speaker and I could sort of hear myself on the other speaker. It probably had the audio quality of Alexander Graham Bell's call to "Watson, come quickly. I need you." but it worked.

Thus I made a transmitter and receiver. I figured out later that this was essentially AM.

I showed it my brother but he didn't care about the details. All he wanted was a bloody QSL card. Bastard.
Title: Re: Wanna' communicate, and broadcast, with light? It can be done!
Post by: redhat on June 11, 2022, 0431 UTC
Complements of Max M Carter, who has a cool radio hobby website as well;

Music on a light beam http://maxmcarter.com/lasrstuf/laserexperiments.html (http://maxmcarter.com/lasrstuf/laserexperiments.html)

+-RH
Title: Re: Wanna' communicate, and broadcast, with light? It can be done!
Post by: Charlie_Dont_Surf on June 30, 2022, 0137 UTC
Thus I made a transmitter and receiver.

I did something similar. A darkened room helped (lower "QRN"  ;D )
Title: Re: Wanna' communicate, and broadcast, with light? It can be done!
Post by: Pigmeat on July 01, 2022, 2313 UTC
 I picked up a little Forrest Mims project book at Radio Shack around 30 years ago that went into detail on building your own LED transmitters and receivers. He preferred red LED's.