| 摘要 |
A clock is so driven by a constant frequency signal through a phase splitter that, to advance or retard the time in increments of half the cycle period of the constant frequency signal, a control knob is turned clockwise or counterclockwise in half-turn increments. A pair of annular potentiometers, each having a single point connected to ground, are driven by the knob in such a fashion that while the resistance of one is cyclically increasing and decreasing, the other is cyclically decreasing and increasing. The separate potentiometers are connected to monostable multivibrators (MV's) triggered by the frequency standard to vary their duty cycles as a function of resistance. Each variable MV triggers a separate MV at the end of its duty cycle to produce output pulses having fixed durations equal to the period of half a cycle of the constant frequency signal. The device is driven alternately by output pulses of the separate MV while time is being adjusted. A cam synchronizes the transfer from one output MV to the other at the midpoint of a half turn of the knob thereby allowing the phase of the frequency standard applied to the motor to be advanced or retarded 90 DEG through one MV and another 90 DEG through the other MV. A magnet is driven by the clock motor in a circular path over a reed switch to periodically produce a pulse to be used as a time signal from the clock and in comparing the time of the clock with a time standard to within a fraction of a second.
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