A swimming pool alarm system for instantly providing an audible or other alarm in response to a person or other object falling into the water. According to the invention, the alarm is adapted to be energized and held in the energized state by electronic switching means that switches from its "off" to its "on" condition in response to a trigger pulse from normally open sensor conductor means which is closable by a momentary splash of water thereon. Such sensor conductor means substantially completely circumscribes the pool closely spaced above the normal water level thereof, whereby the splash or wave motion from an object falling into the pool any place about the periphery thereof will momentarily close the sensor conductor means and thereby turn the switching circuit means "on" to actuate the alarm.

A device for monitoring wave action on the surface of water in a swimming pool in a manner to sound an alarm when someone either accidentally falls into a swimming pool or uses the pool without authorization. A buoy floats on the surface of the swimming pool for detecting excessive wave action. At least one position-sensitive switch is attached to a pivotably mounted float within the buoy for detecting such wave action. A signal from the switch in the buoy is transmitted to a remote alarm unit either by a direct wire connection or by a low power radio transmitter located within the buoy.

A device for indicating a disturbance in a liquid medium, which is especially useful for providing an alarm when a child falls into a swimming pool, comprises a buoyant member carrying a first conductive member, a second conductive member spaced and normally unconnected to the first conductive member, and an alarm circuit. The conductive members are connected to the alarm circuit such that when the liquid in which the buoyant member is floating is disturbed by a predetermined amount, the conductive members are brought into contact through the disturbed liquid, thereby to activate the alarm.

A wave detector for use in a swimming pool includes an electrical circuit provided with an alert member and a power source for operating the alert member. The circuit is normally open between two spaced apart electrodes which substantially eliminates all power drain from the source. When the electrodes are closed by the waves in the pool, the alert member is activated with the circuit further being provided with a normally conductive control member which changes to a nonconductive state for opening the circuit to deactivate the alert member which automatically returns to the conductive state to reset the circuit for further activation of the alert member.

An alarm system includes a floating transmitter which when activated by a wave will generate one short signal and then turn itself off. A radio receiver will detect and verify the time duration of the radio signal, and thereupon activate an audible alarm. The alarm will continue to sound until it is manually turned off.