Lucky Green writes:
Most telephones can be used to monitor conversations in the room they are installed in even while on-hook. No need to ever enter the premises. Just drive it with AC. Look at your basic telephone diagram and remember Xc=1/(omega*C) from your AC circuits class.
The phrase "most telephones" may have been accurate when it meant "500 sets", but now that people generally own electronic phones I wonder whether the lucky one's statement remains true. (It might; I'm an electronics ignoramus.) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | Nobody's going to listen to you if you just | Mike McNally (m5@tivoli.com) | | stand there and flap your arms like a fish. | Tivoli Systems, Austin TX | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~