For millennia people kept their homes of thieves on their own. For this they had to mount the guard, they slept in turns, all this very uncomfortable. Only in the nineteenth century did humanity invent the first alarm called "the electronic Guardian". The system consisted of electromagnet, bell and cables that in case of some intervention of the delinquents joined or separated, which activated the alarm that rang the bell. If the "guardian" was connected to the telephone line, the nearest police delegation received a call.