Another idea: synthesize a 32.768 kHz clock signal from the 1 PPS pulse of the pendulum by PLL, and use this clock to power a modern microcontroller to drive th

Another idea: synthesize a 32.768 kHz clock signal from the 1 PPS pulse of the pendulum by PLL, and use this clock to power a modern microcontroller to drive the 7-segment LEDs and show the current time.