Hello, regarding back EMF and how a flywheel diode is used to protect the transistor, I don't understand how the transistor could be at risk. My thinking is (using a typical transistor - relay circuit) that current is flowing from the positive supply through the relay, then through the transistor and then to negative. When the relay is opened and a back EMF is suddenly generated, the back EMF generated current flows in the opposite direction ie. from the relay back into the power source, so how could it destroy the transistor which is on the other side of the relay and not in the path of the back EMF current ? Thanks for any help. I am getting this mixed up badly somehow. I have attached a pic of how I see things.