Is there a way for me to have an 8 second countdown timer which counts from 8-0. And adds another 8 seconds to the count each time i press a button. I need it to be able to add 8 seconds while counting down. For example the initial count reaches 2 and I press the button, the count will increase by 8 and then count from 10 (2+8) to 0. I've tried using adder circuits but I can't seem to figure out how to implement this function

 

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