TinyCAD is a an open source program for drawing circuit diagrams which runs under Windows. TinyCAD is a program for drawing electrical circuit diagrams commonly known as schematic drawings. It supports standard and custom symbol libraries. It supports PCB layout programs with several netlist formats and can also produce SPICE simulation netlists.
An excellent tool to create, design printed circuit boards in a simple and easy to learn way. ZenitPCB is free for personal and amateur use, limited to 1000 pins, that is more than enought for any amateur radio electronic project
Logisim is an educational tool for designing and simulating digital logic circuits. With its simple toolbar interface and simulation of circuits as you build them, it is simple enough to facilitate learning the most basic concepts related to logic circuits.
DesignSpark PCB is a free PCB design tool, by rs online, designed to help the user to convert their design into PCB faster with unique design options. DesignSpark is a powerful software engine that enables you to capture schematics and design PCB boards and layouts.