Electronic time switch

摘要

An electronic time switch for an A.C. power system and employing a Triac as the switching element is disclosed. The time switch in its normal or OFF state provides a very small amount of current to the load so as to preheat the filament without the filament emitting any appreciable visible light when the load is an incandescent lamp. The user changes the time switch to the ON state by manually depressing a first switch, which causes the time switch to provide full power to the load within a short time thereafter. After a portion of a predetermined time period or ON cycle has elapsed, the time switch starts to decrease the power to the load at an ever-increasing rate until the time switch returns to the normal or OFF state after the lapse of the predetermined time period. The user, by manually depressing a second switch, may immediately return the time switch to the OFF state at any time during the ON cycle. Moreover, the user, during either the OFF or the ON cycle, may check whether the time switch is functioning properly by keeping the second switch depressed. During such a check, the time switch provides less than one-half power to the load. Modifications of the time switch to provide either a remote control feature or a light-responsive feature are also disclosed.