Aux in MCD

Guys good morning again.

I wanted to know if anyone of you have built a diy aux in adapter. I know there are some plans on the net. But i would like to know if you have any personall experience with them?

the one is from here this is what i have made but does not work. and another one is here. So i want to build one working unit. I builted the first one but i doesnt work…!