| 摘要 |
A temperature controller switches between two different temperature levels at predetermined times of the day. At the same time of the day as the actuation of a first switch, the controller will shift from the second to the first temperature level; the actuation of a second switch at a particular time will induce a shift to the second level each succeeding day at that time. Separate timers couple to each of the switches and have 24-hour periods. At the end of their respective 24-hour periods, each timer produces an output signal and begins another period. The switches set the appropriate timer to the beginning of the period so that the changes produced by that timer occur after the expiration of each 24-hour period. The timer may take the form of a pulse counter, with counting pulses derived from the sinusoidal alternating current of the voltage source powering the system.
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