Of course, you've seen it every day, every place, and even in your microwave, toasters, ovens, televisions, toys and stuff like that. All of them featuring a digital clock! Even your computer tells you the time! So, you must be wondering how the hell is this thing made up? Normal analog clocks are all made by 'gears' and quartz crystals (to generate 1-second pulses), but it's different in digital clocks! Ok - there's a simple block diagram of it: Pulse Generator (Wave-Shaping circuit, Oscillator, or Astable Multivibrator system) to generate 1-sec pulses -> divide-by-60 counter (second portion for it to count 0-59 before adding one to the minute) -> divide-by-60 counter (minutes portion) and finally, some gating circuitry for the hours (0 - 12). Every of these counters are interfaced to seven-segment display drivers. It seems complex, but I will have to explain more in layman terms! Here's the pic: (only the seconds part is shown, I've done the minutes part but I dunno where the hell I shoved that thing!) Edit: You might need uh like 6-counters and 6 display drivers (TTL 7490 and TTL 7447) for these (and an AND gate too!), along with a huge supply of 330 ohms resistors, and those 7-seg displays. And also, many wirings! I prefer not to use TTL because I need a darn voltage regulator to bring it to a +5V which is tedious. And, now, all those digital clocks isn't made up of many chips in a huge interconnected breadboard. It's now simplified to LSI (Large Scale Integration) circuits and they even have calendars and alarm clocks!!