Time based changing emission color material

I want to make a “Time based changing emission color material” , i am alright with the the absolute valor of the sine for the emission power but i dont know how to blend the colors by time.

If I’m understanding your question correctly, you should only need to hook up a changing value (whether it’s a time function, or a blueprint controlled parameter) to the the alpha input on that Lerp node you have highlighted in your screenshot.

Thank you very much it helped me alot to understand how these nodes work