All right.
First, you have to have a 555 timer circuit, that starts a 2 minute countdown. It must be triggered by the DD5 output. You can find the 555 timer circuits very easily, with a google search.
Since the output of the timer isn't anywhere near enough to drive a fan, you can make the 555 output drive a small relay, which in turn drives the fan. Just make sure that you spec out that relay very carefully, because you don't want to overload the timer.
|