yEd – Graph Editor by yWorks
yED is a powerful desktop application that can be used to quickly and effectively generate high-quality diagrams. It is well suited for creating functional block diagrams of project hardware as well as state diagrams and flowcharts for project software.
Digikey’s SchemeIt
Scheme-it is an online schematic and diagramming tool that allows anyone to design and share electronic circuit diagrams. The tool includes a comprehensive electronic symbol library and an integrated Digi-Key component catalog that allows for a wide range of circuit designs. Additionally, a built-in bill of materials manager is provided to keep track of parts used in a design. Once a schematic drawing is complete, users can export it to an image file or share it via email with others. Scheme-it works natively in all major web browsers without requiring the use of any plugins. Only registered users are able to share and save designs.
Circuit Diagram
Circuit Diagram is an open-source, easy to use Windows based program that is useful for creating simple circuit diagrams.
