Accurate second pulse signal generation circuit diagram

The precise second pulse signal generation circuit is shown in the figure below. After the SM5511 is powered on, it generates positive and negative narrow pulse signals on its pins 3 and 5 respectively . The two pulse signals are compared and amplified by the high-speed operational amplifier LM318N and then combined into a narrow pulse signal with a period of 1 second. After passing through the D-type flip-flop 74HC74, it becomes a second pulse signal with a period of 2 seconds and a duty cycle of 1 second. Adjusting the trimmer capacitor can change the oscillation frequency of the quartz resonator . Using a high-precision high-frequency counter to adjust the adjustable capacitor can obtain accurate second pulse signals .