This is the Smallest Binary Clock that show the time with just 4 leds.
The brain in this clock is PIC16F84A,The time will be displayed when the 'show' pushbutton is pressed. The digits of the time are displayed in BCD on the four LEDs. Tens of hours is displayed followed by hours, tens of minutes and then minutes.

Step 1: Parts

For this project you will need:

1.PIC16F84A
2.Crystal 32.768khz(you may find in ordinary clocks)
3.Four leds any color
4. Resistors 4x270 ohm
5. Ceramic cap 2x33 Pf
6. Push Buttons 3 peaces

Step 2: Programming and Wireing

First you must program the chip,I use the software ICprog and here is hex code: SmallestBc.
The schematic and wiring you can see here they are very simple to understand.

Step 3: Finish Clock

Here is my 4 leds binary clock,is too fun to have it,I love this clock you may make too be clock watch.
Also I have upload a gif image too see how can you make too look the clock.
Here is my links: