help

S

sparky_1471

New Member

• Mar 4, 2004

• #1

i need the circuit and block diagrams for a countdown timer for an AS project

Please Help

 

Y

Yawdib

New Member

• Mar 4, 2004

• #2

hello

 

R

Russlk

New Member

• Mar 4, 2004

• #3

What is the input, output, voltage available, time to be counted? What is preventing you from doing it yourself? If you post your solution, you will get lots of comment.

 

S

sparky_1471

New Member

• Mar 4, 2004

• #4

hi

the input us 9v, the time to count down from is 60 secs

n a can't do it my self coz am stuck!!!

 

R

Russlk

New Member

• Mar 4, 2004

• #5

A 555 astable and CD4017 decade counter will do it. To count to more than 10, an AND gate is needed.

 

S

sparky_1471

New Member

• Mar 8, 2004

• #6

what chip will i need for the and gate??

 

R

Russlk

New Member

• Mar 8, 2004

• #7

CD4081 or 74HC08 will work. You need to have access to some data books if you are going to do this kind of work. And, become familiar with TTL, ECL, CMOS families.