| 摘要 |
A two terminal timed electric switch which connects in series with but one side of a power carrying a.c. circuit. In particular the timer serves as an effective replacement for the ubiquitous wall-switch type of on and off device used in the construction trades, as in houses, business buildings, and the like. An advantage is that when used as a replacement for an ordinary switch, the timer serves to achieve significant energy savings by turning forgotten lights off when not needed. The timer functions as a delayed-off switch; that is to say the switch and the load are turned on by manual actuation, but turn-off does not occur until some finite time period has elapsed. The timed switch employs all electronic timing elements, e.g. no motors or thermal timing elements or the like. The principal power for operation of the circuits attendant to the timer is obtained by the substantial current flow between the source and the load when the load is "on" and therefore has no necessitous adjoinment with but one side of a power carrying circuit.
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