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Clock signal and legend. In electronics and especially synchronous digital circuits, a clock signal (historically also known as logic beat) [1] is an electronic logic signal (voltage or current) which oscillates between a high and a low state at a constant frequency and is used like a metronome to synchronize actions of digital circuits.
Prompted by this signal, the visual cortex once again resumes processing visual information. [5] For the student, his eyes have now reached the clock and his brain's visual cortex begins to process information from his eyes. However, this second efferent trigger also communicates to the brain that a period of time has been missing from perception.
Of the several possible cues (known as zeitgebers, German for 'time-givers') that can contribute to entrainment of the circadian clock, light has the greatest impact. [ 2 ] [ 3 ] Units of circadian time (CT) are used to describe entrainment to refer to the relationship between the rhythm and the light signal/pulse.
In digital electronics, a synchronous circuit is a digital circuit in which the changes in the state of memory elements are synchronized by a clock signal. In a sequential digital logic circuit, data is stored in memory devices called flip-flops or latches. The output of a flip-flop is constant until a pulse is applied to its "clock" input ...
A signal from a peripheral device would reset this latch, resuming CPU operation. The hardware logic must gate the latch control inputs as necessary to ensure that a latch output transition does not cause the clock signal level to instantaneously change and cause a clock pulse, either high or low, that is shorter than normal.
The physiological changes that follow these clocks are known as circadian rhythms. Because the endogenous period of these rhythms are approximately but not exactly 24 hours, these rhythms must be reset by external cues to synchronize with the daily cycles in the environment. [ 1 ]
A circadian clock, or circadian oscillator, also known as one’s internal alarm clock is a biochemical oscillator that cycles with a stable phase and is synchronized with solar time. Such a clock's in vivo period is necessarily almost exactly 24 hours (the earth's current solar day). In most living organisms, internally synchronized circadian ...
Flip-flops only flip when triggered by the edge of the clock pulse, so changes to the logic signals throughout the circuit begin at the same time and at regular intervals. The output of all memory elements in a circuit is called the state of the circuit. The state of a synchronous circuit changes only on the clock pulse. The changes in signal ...