This is a design circuit for binary clock circuit. This circuit is the same hardware as the led matrix project using a 16F88 PIC microcontroller and an LED matrix. Its worth taking a look there as the same hardware description applies on how to multiplex the display. This is the figure of the circuit;
To display hours, minutes and seconds (2 digits each) you need 6 binary digits in total (depending on whether you use a 24 hour clock the top digit needs only 1 or 2 LEDs).
