Circuit Diagram is a free, open source application which enables you to make electronic circuit diagrams and export them as images.
This software is available for windows OS and not require many resources , but in same time it don’t has many features .

TinyCAD is an open source schematic capture program that can be used to draw your own circuit diagrams.
Tiny CAD has an user friendly interface and is very easy to use . In TinyCAD you can lay out circuit diagrams using the supplied libraries or you can easily create your own symbols ( if you don’t find symbols you need ) . Also you can find many other libraries on the internet .
Once the circuit diagram has been drawn you can you can use some other functions of the Tinycad program for check your design, add symbol references , create parts list , etc.