Patent ID: 9711028
Date: 2017-07-18
CPC Classifications: E06C,G08B

Claim:
1. An electronic warning circuit for installation on a ladder of the type having a plurality of spaced apart rungs for warning a user of approaching an end of the ladder in a single direction, said electronic warning circuit comprising: a first sensor comprising an electrical switch, affixed to a first one of a pair of rungs of a ladder proximate an end thereof, responding to placement of a first of a user's feet on said first sensor by changing said first sensor from a non-conducting state to a conducting state, for an entire time the first of the user's feet is placed on the first sensor; a second sensor comprising an electrical switch electrically connected in series with said first sensor, affixed to a second adjacent one of the pair of rungs of the ladder proximate the end thereof, responding to placement of a second of the user's feet on said second sensor by changing said second sensor from a non-conducting state to a conducting state beginning from the time of initial placement of the second of the user's feet on said second sensor, for a predetermined period of time, and returning to the non-conducting state after the predetermined period of time has elapsed, said predetermined period of time being less than the time the user takes to move his feet from one rung to the next rung; a latching relay having a start terminal electrically connected to said second sensor, said latching relay also having a power input terminal a common terminal and a load output terminal; a power source having a power output terminal electrically connected to said first sensor and said power input terminal of said latching relay, said power source also having a common terminal; and a sound device electrically connected to said load output terminal of said latching relay and to said common terminal of said power source to complete said electronic warning circuit; wherein said load output terminal of said latching relay, and thereby said sound device, are energized when both said first and second sensors are in conducting states at the same time in response to placement of the first and second feet of said user on said first and second sensors as the user moves in the direction of the first rung to the second rung.