How do I make a Virtual Joystick for Mobile Devices?

Hey Guys,
today I started to create my first mobile game. As I want to test it while programming, I need some sort of Virtual Joystick for the controls. Since I don’t really know how to handle Inputs on mobile devices and the scripting API can’t help me, I looked for a Joystick on the internet. Unfortunately, I haven’t found one that works for me.

Can anybody tell me/show me a tutorial how I create a simple Joystick that has the same location on every device and returns the current angle?

Here’s one from the Unity wiki… what is about the ones you’re finding on the internet that don’t work for you? There are a ton of links that come up when searching…