I have built a few of these. I have a Robojax question. There are two amp's in the LM358. Sensitivity and general operation is (I Believe) effected by the unused amp. It should be terminated. I tried to incorporated the second amp in some way but not usefull in this IR application. Terminating components adds a voltage divider and a ground to quiet the idle amp. My transistor version is still on the bench. Is there a single Op Amp I can use instead? I get the same resuslts as the factory module, but it is not stable.