i want 1 output input signal selected by 3 selection lines is multiplexed to 8 different outputs, i know that Decoders make that but i couldn't find any datasheets for that can anyone help
What you are looking for is a "1 of 8 line selector". One such part is the 74x151. If you do a Google search for "1 of 8 line selector" you'll see plenty of alternatives.
I'm a bit confused. I think the wants the OPPOSITE of the your '151. OP said 8 outputs (I THINK, that's what he's trying to say). I THINK he want's a DEMUX not a MUX.
Bustigo, could you restate the question? Are you looking to switch one input to one-of-eight outputs, or switch one-of-eight inputs to a single output?