| 摘要 |
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. When the count reaches a value equal to the number representing the solar time set by the user on the turn-off time switches, a digital comparator causes the load to be disconnected from the AC source.
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