12v to 5v 7805 circuit diagram

In some cases, it is necessary to add a 5V power supply, but the transformer does not have an idle winding. In this case, the 7805 can be connected to the 7812. The picture below shows the 7805 connected to the 12V voltage point after being stabilized by the 7812. The disadvantage of this method is that the 7805 The loss is a bit large and it generates heat. Because the input and output voltage difference of 7805 is too large, it has reached 7V.