Automatic video switching.... ?
 

I'm looking for something that I can connect 3 RCA video cables into that can switch between all 3 videos at random intervals like security system monitors do. so it would go from 3 RCA Video into like the box, then out to 1 RCA video cable into like a tv or monitor. Each shows for about 4 seconds and then switches to the next. I need something automatic just like the surveillance monitors are.. Thanks