Abstract: A timing device which is associated with a light level sensor and which is arranged to provide a time-out signal to a relay after a predetermined time has elapsed following detection of a low light condition and initial energization of the relay. The device provides for synchronization of an initiation time T.sub.1 and, hence, a time-out signal generating time T.sub.2 with respect to a periodically occurring event time T.sub.3 (for example, sunset time) in order that the desired time of generating the time-out signal might be re-established following interruption of power to the device. Should loss of power occur, the last entered event time T.sub.3 is employed to synchronize the initiation time T.sub.1 and, hence, the signal generating time T.sub.2, when detection of a predetermined light level next occurs following re-establishment of power to the device.

Abstract: A method of and apparatus for controlling the opening and/or closing of contacts of an electro-mechanical switching device in an alternating current circuit. Detection is made for the existence of a voltage having a level which is indicative of a back emf in a load circuit immediately following opening of the contacts, and if such a voltage level is detected an incremental adjustment is made in the phase angle at which successive actuations of the contacts are effected. This procedure is repeated under the control of a microprocessor until such time as the voltage which is indicative of back emf reduces to zero, this providing an indication that contact opening is occurring at a time corresponding to zero current crossing in the alternating current waveform.