[mrblaine]

Go to you favorite stereo store. They typically have several versions of time delay switches for various applications with ranges from seconds to minutes.

They use them in alarm install to delay certain features.

You can get them that start counting down upon application of voltage or ground or a manual trigger, or a pulse sense.

I'm also pretty sure I have one in the garage if you'd like me to rummage through a drawer and find it so you can test your idea.