2 4026's would give you a /99 counter and display the count on 2 7 seg displays, the carry out on the msd would give you the /100 signal to trigger the fans.
A simple mains plug in timer with a mains relay conected to its o/p would give you a 8 hour or whatever you want reset signal.
If your 2 second pulse input isnt clean, such as from a contact you'll need a 555 to clean it up.
A simple mains plug in timer with a mains relay conected to its o/p would give you a 8 hour or whatever you want reset signal.
If your 2 second pulse input isnt clean, such as from a contact you'll need a 555 to clean it up.