Clock/timer

[stevedabear]

How can i make a simple circuit, to create a clock, which counts down from 3 minutes, 2 minutes or 1 minutes. ( requiring adjustable settings )
The clock is to be fed into three seven segment displays.

Can anyone help ? I'm thinking of something along the lines of a simple D type formation.

Thanks in advance

 

[audioguru2]

Hi Steve,
There are some digital stopwatches in our Projects section:
http://www.electronics-lab.com/projects/oscillators_timers/014/index.html
http://www.electronics-lab.com/projects/oscillators_timers/015/index.html