how are intercoms normally wired?

[dpopiz]

so I'm trying to plan a prank for next year at school. I want to play something over the outdoor intercom speakers, and I'm thinking I could probably just open up one of the speaker boxes and wire an audio source into the circuit. do you think that would work? do school intercoms normally have some sort of protection to prevent a spliced-in signal from playing through the whole system? is there any kind of standard wiring that this type of intercom typically uses, or does somebody even know what you'd call the type of intercom announcement system they have at schools? I noticed today that there is one speaker box on the gym locker room building that is broken the wall and hanging by the wires, so tomorrow I could get back to you guys on how many wires it has. only trouble is that I think that box may be on a different system than most of the school because the ones near the gym sound shower bells that aren't heard anywhere else in addition to the normal bells.

 

[capybara]

the ones i know have the regular 2 wires to every speaker, and they work thru the phone system.
you pickup the phone, dial a code to make an intercom announcement. but yes, there is no reason you cant hook a new input up at any location u have access to the
2 wires.

 

[SnowBoarder9455]

Sounds fun

 

[dkozloski]

Ordinarily PA systems are wired with a high voltage line (85V+) from the PA amplifier to impedance matching transformers at each speaker. This is to reduce losses over the long distances involved. My guess is that if you try driving the system at another point by tapping in you are running the risk of doing enough expensive damage to get yourself a jolt in the slammer. Why not spend your time doing good deeds for the indigent. You'll feel a lot better about yourself.

 

[grant2]

Cuz he's a punk!

If the speakers were wired to act as microphones then daily noise beside each of the speakers would get transmitted into the system.