Minute impulse clock technology is best described using the 3-way stairway light switch metaphor. The stair light is the clock motor, the upstairs switch is actuated one way or the other when the clock shaft has advanced one minute on the dial, and the downstairs switch is actuated by a controller to indicate if we are currently in an even minute (up) or an odd minute (down). If the clock has advanced to the current minute, the light will be off (dial motor not running). When real time advances to the next minute, the downstairs switch changes, energizing the light (dial motor running). When the clock has advanced to this new time it changes the state of the upstairs switch turning off the light (dial motor not running). This continues keeping the clock dial in perfect sync with real time.
To provide for power outage recovery, the controller advances a memory register each time it commands the clock movement to advance. When power is restored after an outage, the controller will command the dial to advance at a faster rate until this register equals the real time.
In the case of Daylight Time adjustments, the clock will advance at a faster rate to catch up with the new real time, or stop the clock to wait for real time to catch up.
[[Category: Clocks]][[Category: Electrical]]