From CMH Software:
The Constructor program makes the creation, testing, trouble-shooting, teaching and printing of electrical ladder diagrams, schematics and one line diagrams fast and easy. The circuit will perform the same as a hard wired electrical circuit. The design can be edited and re-tested saving valuable time when it comes to hard wiring circuits and trouble-shooting scenarios. This program is unique in its ability to test an electrical circuit. You can see the power flow in the diagram and hear the sound effects when a motor or siren is energized. Once designed, any circuit can then be virtually energized and operated on your computer monitor.