Step 2: Build the 555 ic one-shot timer
You can adjust the amount of time that the timer stays on by varying the values of the resistor to pin 7, and the capacitor to pin 6.
Time (seconds) = 1.1 x R x C
It is a good idea to set up the circuit on a breadboard to get the bugs worked out prior to soldering. However, in my experience, things can behave differently once they are reassembled onto a circuit board. I had to adjust my component values a little bit once i built the circuit on perf board.
Image courtesy of Rob Paisley.