Abstract: An annunciator for indicating the removal of an electrical plug from the electrical receptacle. The electrical receptacle includes neutral switching contacts actuated in response to the insertion of a plug into the receptacle. An input circuit in the annunciator apparatus monitors the state of the neutral switching contacts and couples signals produced when a plug is removed to a latching circuit thereby to produce an audible or electrical indication of plug removal. The input Circuit and latching circuit are electrically isolated, and the annunciator detects any attempts to disconnect the apparatus from an external power supply or to remove any internal battery.

Abstract: An electrical receptacle for use with an annunciator for indicating the removal of an electrical plug from the electrical receptacle. The electrical receptacle includes neutral switching contacts actuated in response to the insertion of a plug into the receptacle. An input circuit in the annunciator apparatus monitors the state of the neutral switching contacts and couples signals produced when a plug is removed to a latching circuit thereby to produce an audible or electrical indication of plug removal.

Abstract: An annunciator for indicating the removal of an electrical plug from an electrical receptacle. The electrical receptacle includes neutral switching contacts actuated in response to the insertion of a plug into the receptacle. An input circuit in the annunciator apparatus monitors the state of the neutral switching contacts and couples signals produced when a plug is removed to a latching circuit thereby to produce an audible or electrical indication of plug removal. The annunciator circuit does not provide an alarm in response to the insertion of a plug or to an absence of a plug.

Abstract: Theft of electrical appliances and the like is deterred by an alarm (40) which is activated when the appliance is disconnected from an impedance sensing alarm apparatus (10). A signal of a first magnitude is presented at an input of a detector (26) when the appliance is connected to the alarm apparatus. A signal of a second magnitude is presented at the input of the detector (26) when the appliance is disconnected from the alarm apparatus. The different magnitude of the signals is sensed by the detector (26) which, in turn, generates a control signal that activates an audible alarm (40) or the like.

Abstract: Theft of electrical appliances and the like is counteracted through provision of an alarm activated by removal of an electrical power line plug from an outlet by opening a normally closed or closing a normally open pair of contacts to gate a thyristor or relay and provide power through the thyristor or relay to a light, audible alarm or the like, the contacts being entirely hidden within the outlet. The alarm may also be activated by cutting a power line.