I am making DIGITAL CLOCK in which i m using
1. 6 74LS90(BCD counters)
2. 6 74LS47(Decoders)
3. 6 7seg Display(common anode)
4. 6 74LS08 n 74LS32( AND N OR GATES)
5. 1 555 timer IC
according to datasheets of the ICs, i require 5±0.25V n 1-16mA current range for the operation, suggest which power supply would be appropriate?

 

LM7805 - You need the big heat sink.
LM317 - Adjust to 5.25V, also need the heat sink.
LM2576-5.0 - 3A, this is the best.

LM2576-5.0 datasheet.
http://www.datasheetcatalog.org/datasheets/90/61729_DS.pdf

 

Or you could get a cell phone power supply, depending on where you are getting your clock from. If you looked at the thread I pointed you to I had a fairly cheap crystal oscillator/divider that would provide a 1 Hz source. There are many ways to buy 5V DC wall warts.

PS: Please stop posting 2 threads on the same subject, you are just creating more work for the moderators, and it will not work.