This is an electronic circuit simulator. When the applet starts up you will see an animated schematic of a simple LRC circuit. The green color indicates positive voltage. The gray color indicates ground. A red color indicates negative voltage. The moving yellow dots indicate current. To. In terms of the diagram, that means you would have to draw a circle that would pass through every subregion of the following diagram: Imagine an ellipse cutting through the lower half of the diagram so that it cuts across 4, 2, 1, 5 and 7.. The next diagram will provide some general familiarization with ladder logic and with Timer relays: I made this diagram for a member who wanted an automatic system to replace the water in his fish tank..