How To Hijack Mosque Speaker Systems


Overview

This is an example of a simple method which can be used to "hijack" Public Access (PA) speaker systems non-invasively.  That is, without the need for any direct hardware or wire connection.  This is good for those quick "hit-and-run" missions, like if you wanted to take over some camel-humper's Mosque speaker system.  You can even take over a school's PA system (and has been tested this way) if you don't want to travel to some third-world shithole (California).

How It Works

It is quite simple in operation.  A normal PA speaker system just consists of a microphone, or other source of audio, connected to an audio amplifier (usually under 100 Watts) and an array of speakers.  The audio amplifier sends its output signals (current) via a series of wires to the individual remote speaker(s).  Speakers are transducers.  That is, they convert this flowing current into mechanical energy (vibrations) via the coil and cone in the speaker.  We then hear these mechanical vibrations as audio (sound waves) coming from the speaker.  Some PA speaker systems can contain arrays of tens, or even hundreds, of speakers.  In this example, we can only hijack a single speaker.

To hijack a speaker, without any direct mechanical connections, all you need to do is wrap some wire around the positive lead (+) of the target speaker.  This wire-wrapping acts as a large inductor, and our new audio signal (current) is induced into the speaker's wiring.  This does work, but don't expect any overwhelming results.  It can't be used to simulate a direct-connected 100 Watt audio amplifier.  It will freak the hell out of people though...

If you can't access or wrap around a speaker's positive wire, it is possible to place a wire-wrapped ferrite rod, like an AM radio antenna, near (parallel) the speaker's wiring.  This magnetic field will also "induce" a new audio signal.  This setup doesn't work quite as well, and the ferrite rod is limited on the amount of power it can handle before saturating.

In both examples, you'll need to use a high-power, surplus (it can blow up) car audio amplifier to induce the new signal.  Car audio amplifiers are the best choice as they tend to be cheap and they'll easily run from +12 VDC, perfect for portable operation.  You'll also need a source of audio.  A CD / MP3 player or microphone is best.  The microphone's output signal may need to be "brought-up" to line level in order to feed the car audio amplifier.  Pick a microphone with an internal pre-amp or you can easily build one your self.  Search Google for: "microphone pre-amplifier schematic".  You only need something simple.

When wrapping your "inductor" around the speaker's wire, it is best to use small-gauge, enameled (insulated) magnet wire.  Solid-core #28 or #30 AWG works well and is available from Radio Shack.  Old car speakers are also a good source of this wire.  If fact, study how speakers work to get a good idea on how this whole setup works.  Ideally, your "inductor" should have an impedance equal to the output impedance of the car audio amplifier (4 or 8 Ohms, usually).  This can be difficult to determine (and achieve) because it usually amounts to thousands of wire-wraps.  You can get by with only a few hundred wraps or so if you use short, interrupted audio transmissions.  A long, continous audio transmission with an amplifier feeding an impedance mismatch is certain to destructively damage the audio amplifier.


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