\begin{tikzpicture}[scale=0.9,every node/.style={transform shape}]
	\onslide<10->{\node [output_neuron] (out0) at (-3,12)  {} ;}

	\onslide<2->{\node (input0) at (-4,8)  {$x_1$};}
	\onslide<2->{\node (input1) at (-2,8) {$x_2$};}

	\onslide<2->{\node [hidden_neuron] (hi0) at (-6,10)  {  } ;}
	\onslide<2->{\node [hidden_neuron] (hi1) at (-4,10)  {  } ;}
	\onslide<2->{\node [hidden_neuron] (hi2) at (-2,10)  {  } ;}
	\onslide<2->{\node [hidden_neuron] (hi3) at (0,10)  {  } ;}



	\onslide<9->{\node (bias) at (-6,9)  {$bias=$-2} ;}

	\onslide<13->{\node (output0) at (-3,13)  {$y$} ;}

	\onslide<12->{\node (w1) at (-5,11)  {$w_1$} ;}
	\onslide<12->{\node (w2) at (-3.8,11)  {$w_2$} ;}
	\onslide<12->{\node (w3) at (-2.8,11)  {$w_3$} ;}
	\onslide<12->{\node (w4) at (-1.85,11)  {$w_4$} ;}

	\onslide<5->{\draw [->, thick, red] (input0) -- (hi0);}
	\onslide<5->{\draw [->, thick, red] (input1) -- (hi0);}

	\onslide<6->{\draw [->, thick, red](input0) -- (hi1);}
	\onslide<6->{\draw [->, thick, blue](input1) -- (hi1);}

	\onslide<7->{\draw [->, thick, blue] (input0) -- (hi2);}
	\onslide<7->{\draw [->, thick, red] (input1) -- (hi2);}

	\onslide<8->{\draw [->, thick, blue](input0) -- (hi3);}
	\onslide<8->{\draw [->, thick, blue](input1) -- (hi3);}

	\onslide<11->{\draw [->] (hi0) -- (out0);}
	\onslide<11->{\draw [->] (hi1) -- (out0);}
	\onslide<11->{\draw [->] (hi2) -- (out0);}
	\onslide<11->{\draw [->] (hi3) -- (out0);}

	\onslide<13->{\draw [->] (out0) -- (output0);}

	%\node at (-6,1) {red edge indicates $w$ = -1};
	%\node at (-6,0) {green edge indicates $w$ = +1};

\end{tikzpicture}