You can build an amazing LED based clock where both analog and digital signals are involved. This ‘mixed signal’ based clock has an analog readout, with all the digital signal processing involved. Dos4ever member Ronald Dekker has shared his design so called as ‘A Mixed-Signal LED Clock‘ can be taken as a reference for you to start with.
First of all the LEDs are connected in a matrix fashion so that the second, minute and hour LEDs are time multiplexed. The major ICs that is required in your build are:
PIC16F84 Microcontroller, 74HC563 8 bits latch, and HEF4028 1-of-10 decoder.