Yahya Tawil over at All About Circuits posted a detailed how-to on building a control circuit with adjustable working time via Wi-Fi:
In this article, you’ll learn how to build a system that can turn DC loads on and off using a mobile application. You’ll also learn how to perform this task via immediate actions or via timers set in advance for switching loads on and off.
You can implement this system in environments where you need to set your DC load for a specific time. This will allow you to use our Android application without any need for a hardware interface, keypad, and LCD screen.
More details at All About Circuits project page.
Check out the video after the break.