Warning device and receptacle adaptor

Claim 1

A warning device for indicating loss of power to an electrical unit from a power source by power failure or by disengagement of a plug between the electrical unit and power source, which comprises: a relay switch having a coil and a spring-biased blade which moves to and from a contact, and is biased against the contact and drawn away from the contact and held toward the coil when the coil is energized, means connected to the relay switch for connecting the relay switch across a power source, a receptacle adaptor for receiving the blades and grounding prong of a grounded plug, including a housing having front and back surfaces, contact members extending into the housing from its front surface for receiving the grounded plug blades, a channel pin the housing for receiving the plug grounding prong, the channel extending through the housing from its front to back surfaces, a pin having a front end and a back end, mounted in the channel for reciprocating axially therethrough, and biasing means pin engagement with the channel and pin for biasing the in toward the front surface in a manner that allows the tip of the plug grounding prong to come into engagement with the pin front end when a prong is inserted into the channel, and allows the pin to be thereby moved against the bias axially through the channel to an extent that the pin back end extends beyond the housing rear surface, a second switch connected to the relay contact, the second switch having a contactor and means for rendering the pin communicable with the contactor, such that the second switch is closed when the grounding prong is removed from the receptacle channel and the pin is moved axially to its spring-biased position, and an on-off switch having two poles, one pole being connected to the relay blade, for activating and de-activating the warning device, a battery having one pole connected to the other pole of the on-off switch, and alarm means connected between the on-off switch and the battery, and between the battery and the on-off and second switches, said alarm means being activated when power to the relay is lost or when the grounding prong is withdrawn from the receptacle adaptor.