Further Details
I would Like to implement up-to HH:MM:SS.
So, in this case, I am led to believe that the time and wire Saving will be enormous. The better part of using Multiplexing is I think not the economy of were saving but the simplicity in using less wires, since less wires to connect less chance to connect incorrectly!
My initial idea is to
1. Generate High Frequency using 555 astable
2. Send this pulse to a 6 bit binary counter (perhaps derived from 8-bit counter)
3. Send the output of this counter to a 1-of-6 Decoder (pherhaps derived from 1 of 10 Decoder)
4. Use the output of the decoder to select which of the six 7-segment decoder to enable.
This part of enabling one of the Display is I think OK.
If I setup my Clock somewhat like this
1. Generate 1 Hz clock pulse
2. Send this pulse to the 6 Cascaded BCD Counters
3. Connect each of the BCD Counters to A single BCD TO 7-seg decoder
4. And of course Make some logic to reset at 60s, and 24.
What I don't know is how to setup things so that only that BCD Counter sends output which corresponds to the Display I selected!
(I have never used Tri-state Logic, But if the problem demands its use, I will be happy to learn, Afterall we do projects to learn new things!