In the section on rectifier circuits, I used Tiny to model the diagram of the dual-polarity full-wave center-tap rectifier for experimentation. Using Tiny's Oscilliscope, I setup its leads as shown in the diagram, but I only get the positive wave on both sections (top and bottom). The diagram shows the positive lead on the top of each section. The only way I could get the negative wave on the bottom section was to reverse the two blue diodes. Have I possibly done something wrong or is there a mistake in the diagram? Thanks much.