Binary Clock

This here is my current draft of my binary clock design, as requested by my friend a while ago (I'm slack).

This binary clock counts seconds, minutes and hours in binary and uses two different colours for AM and PM. 

Parts List:

3 x 74LS393 

1 x 555 timer

2 x 74LS21

1 x 5.1 V zener diode

Various resistors
18 x 1000 uF capacitors
1 x 10 uF capacitor
1 x 0.1 uF capacitor

2 x NPN BJTs

4 x Momentary ON button switches (for changing the time)

1 x switch (for on and off)

1 x switch (for clearing time)

18 x LEDs of AM colour

18 x LEDs of PM colour

1 x 9 V battery

The battery and the switches are the most expensive part of this circuit (provided you don't buy ridiculously expensive LEDs). You could probably pick them up for a reasonable price on eBay, but the switches will probably be at least 50c each, and the battery is likely to cost you around $2. All up, it should cost around $10, not including wires, solder or circuit board, so all up, probably around $13. Buying the ICs, transistors, diodes and LEDs in bulk will make it cheaper in the long run, and then you'll have lots of spare parts in case you screw up, want to build another one, or if you want to make something else. The diodes in particular will come in handy.

Pins 3, 4, 5, 6, 10 and 11 of the first and second 74LS393 and pins 3, 4, 5 and 6 of the last 74LS393 are each connected to the following circuit:

The AM LED connects to the AM lead in the main schematic, and it is the same with the PM LED.


This schematic is liable to change at any moment, but if you have any questions, suggestions or queries, please leave a comment.