HiJack Public Speakers

[TheDramatic]

Hi folks,

first of all I would like to say that you have some really smart project designs on your forum. Congrats! Very very nice forum! *thumbsUp*

Maybe it is not the best way to start posting to a new forum, but I have a (maybe) really stupid question. (Please excuse me if it is to trivial or dumb because I'm not really into analog electronics.

Some time ago I have seen a movie where a guy developed a Software to hijack video playback devices wirelessly feeding a custom signal for playback on all displays in the vicinity. I know thats science fiction and just not feasible because of the vast amount of different protocols, device types and encryption methods.

I wonder if there is a way to build a similar device if you reduce the complexity of this idea to analog signals and simple speakers instead of digital video playback devices.

Assuming that you have access to the wiring (fat cables mounted on walls) of audio equipment often found on plazas or train stations.
Those speakers are usually powered with their operating voltage 24/7 but do not receive any modulated signals.

Would it be possible to feed a signal without directly accessing the wires. (maybe: Induction via a powerful coil)

Thanks for your ideas in advance.

Dramatic Greetz.

 

[audioguru2]

Most audio cables are shielded to block interference.
Some audio cables are balanced to cancel interference.
So your idea will not work.

 

[Hero999]

It's also illegal, even if it's possible.

 

[mattphelps]

The answer is yes assuming you have access to the speaker wirings. But you need a special device much like a receiver to be tapped into the wirings. You can even tapped into billboard displays were you only need to tapped into the billboard's video cable. You need a separate device to receive your input.