Abstract: A light-responsive control circuit for the purpose of connecting a load, generally an electric lamp, to an AC source every evening at dusk and disconnecting the load from the AC source later each night at a solar time established by the setting of timepiece-like controls, all without the need for user synchronization of included timekeeping circuitry with the time of day. Starting at dawn each day, a light-responsive switch causes a counter to measure the passage of time by accumulating a count representing one-half hour for each hour that passes, by counting alternations of the AC source voltage. At dusk the count approximately represents the number of hours that have elapsed since solar noon and at that time the light-responsive switch causes the load to be switched on and also causes a signal having a frequency double that of the AC source voltage to be applied to the counter to maintain a correct representation of the solar time of day.

Abstract: A two-terminal control and power switching circuit for substantially reducing electric current flow in the primary winding of an energized power transformer when no load is connected to the transformer secondary. A triac, in series with the power transformer primary and AC source, remains off when a load remains unconnected to the secondary of the power transformer. An oscillator circuit causes a resistive path to be periodically connected across the nonconducting triac. When a load is connected across the power transformer secondary, the resulting increase in voltage developed across a portion of this resistive path is sufficient to cause voltage-amplitude-sensing circuitry to fire the triac.