hi, i have question.. can the IC cd4017 (decade counter) be used as countdown tool? i mean, i know it can count from 0 to 9. can it be implemented to count from 9 to 0?

 

Reading data sheets can be useful. All the 4017 can do is count up.

Of course, nothing says you can't interpret the count as decreasing.

 

Negative logic, positive logic, its all relative.

 

Negative logic, positive logic, its all relative.

Since the 4017 has 10 decoded outputs (only one high at a time), is this is relevant? I can't see how. Beenthere's suggestion will work, though.

 

Since the 4017 has 10 decoded outputs (only one high at a time), is this is relevant? I can't see how. Beenthere's suggestion will work, though.

So instead of tying, say, LED1 to Output1, and LED2 to Output2, and LED10 to Output10, you would tie LED10 to Output1, and LED9 to Output2, and LED10 to Output1.

Why are the simplest solutions often the hardest to see?

--Rich