Countdown timer project

Task: Push a button, countdown 5 minutes, after that buzzer and LED goes on to alert people. And 7 segment display is also required during counting

My idea:
(Since this is my first year to study electronics, so I don't know am i making myself clear)
1) Switch
2) Latch (Bistable? SR Flip-flop?)
3) Astable
4) 4510 counter (what about the load?)
5) 4511 decoder
6) 7 segment display
7) Logic gates( NOT gate? when it counts to zero it held high?)
8) Buzzer & LED

If my idea would work(probably not), I also want to know how to make the 7 segment display to show the actual minutes and seconds. i.e. 5:00->4:59->4:58------->0:00

I want to know the theory behind it, and the actual circuit diagram. (Do it in yenka will be much appericated) Please help.

p.s. English is my second language, so please feel free to ask if you have no idea what I am talking about.

hi,
Look at this links for ideas.

Use a cut down version of the multiple digit counter and convert the 555 clock output to 60sec interval.

https://www.electro-tech-online.com...asic-3-digit-led-decade-up-down-counter1.html

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what should i do?

a7q6vdyy said:

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what should i do?

Click to expand...

hi,
The link works OK for me.?

I have clipped a part of the counter image, its shows an example of a single digit counter.

Can you explain the theory behind it? I find it quite hard to understand it...