how one can made a digital clock

A bunch of decade dividers, and a couple BCD-to-7-segment decoders.

If you want to do it from transistors or even tubes, expect to use a couple hundred pieces. For relays, ingenious use/selection may get you in under a hundred, if rather noisy.

Tim

No please ?

Gmail and Google groups score 0/10 again !

Graham

The simplest way is to buy one. (And probably the cheapest one)

And certainly that makes them very available.

If the goal is to build a clock, then obviously it's not a good suggestion.

But if the goal is to use the clock for something else, then it makes the most sense. Buy a cheap digital clock, be it off the shelf or used, extract the actual clock and then use that like a module.

It's not all that different from the big era of "clock builders" who were buying National Semiconductor clock modules, and putting them in boxes. Or even the kits that directly proceeded them, where the builder just had to solder the parts to the supplied board.

Michael

I'm guessing that software has to be the easiest and cheapest way of modelling a clock.

Do you have any other criteria?