Hi all,
I want to design a circuit. which will add the two input signals. Now if one of the signal is ON and the other is OFF, then the first input signal must be transferred to the output without any changes. And if the second one is ON and the first one is off. Then the output must be of the same value as at the input of the second input (means with no changes). Now when both of the inputs are ON. then the output must be equal to the addition of first input voltage + second input voltage. So here can I use 741 i.e. Op amps or not, what should I use to get such type of output.

Thanks in advance

 

http://www.allaboutcircuits.com/vol_3/chpt_8/8.html