公开(公告)号：US3803576A

公开(公告)日：1974-04-09

申请号：US27111072

申请日：1972-07-12

Applicant: EMHART CORP

Inventor： DOBRZANSKI J ,  DOYLE W

IPC: G08B13/08 ,  G08B13/00

CPC classification number: G08B13/08

Abstract: Circuitry is disclosed for sounding an alarm horn when a window or door is opened, and an associated limit switch is closed, the circuitry providing for predetermined time delays suitable for use in either one of two possible modes of operation. A console is provided in the residence to be protected, and contains a battery power source for operating the circuitry, a key control switch, and a mode selector switch. One mode is suitable for use at night when the occupant of the residence is at home, and the circuitry provides for a time delay in sounding the alarm following closing of one of the limit switches, in order to allow the occupant time to close any open exit door or window. The second mode is for use when the occupant leaves his residence unattended, and two time delays are provided for in this second mode prior to sounding any alarm, and after switching the system on. One of these delays is the same as that outlined above, the other delay being of variable duration and in sequence with the first mentioned delay. The occupant has the same nine seconds to re-enter and deactivate the system once he has left his residence, but he also has the benefit of a secondary delay on leaving his residence. Thus, he may activate the system in mode two, open an exit door within a certain time, and procrastinate for any amount of time before leaving and closing the door behind him. Having closed the door behind him he will have the benefit of a short delay on re-entry to allow him to deactivate the system.