How to switch motor rotaion

[Vinny_Ds]

I want to built a beam robot with the circuit attached. I also want to modify it so that the dc motor can switch its rotation. It has to be as simple as possible and it has to depend on two phototransistors that indicate which side it has to rotate.

 

[Audioguru]

Your original circuit uses low current transistors and they do not have resistors that limit their base current so they will probably blow up.

An "H bridge" circuit can reverse the rotation direction of a DC motor. The transistors in the H bridge have resistors to limit their base current like this: