Electronic design automation (EDA or ECAD) is a category of software tools for designing electronic systems such as printed circuit boards. In my professional life, I have been work apart from this domain, and only now because of renewed interest in electronics, I have come back to do some research. I was pleasantly amazed by what I found.
Schematic and PCB Layout Editors
EAGLE (Easily Applicable Graphical Layout Editor) is a very popular (and free) solution for PCB design, including Schematic Capture, Board Layout and Autorouter.
Other tools are specifically focused on the Arduino that allows users to document their prototypes, share them with others, teach electronics in a classroom, and to create a PCB layout for professional manufacturing.
Arduino Platform Simulation
PCB Board Creation
You can crate printed circuit board (PCB) with the aid of some web sites. You submit your PCB design; they add your design to the batch of orders. When the batch is big enough, the batch is set off to be manufactured.
SPICE
SPICE (Simulation Program with Integrated Circuit Emphasis) is a general-purpose, open source analog electronic circuit simulator
Jeff's Skinner Box 
Nice summary again, Jeff. I’ve used both Eagle and Fritzing and find them both difficult for the occasional user because you have to spend more time learning their quirks than you spend putting together your circuit. But, they’re the tools we’ve got and they’re free!
Ralph …Thanks for your insights on the tools. I suspected that.
I have been checking out your blog and I’m impressed. Your doing some of the things I want to do. What sparked my renewed interest in electronics was some internet research on robotics with a neighbors kid. I was surprised by what one could do via DIY and considered a robot as my first real project.
I have changed course since then and now considering home automation. I got some embryonic ideas around remote control of deck lighting that can expand into other things. It will involve Arduino, Xbee, and a Raspberry Pi. It will force me to learn several domains and relearn some old skills. Its the learning part that is at the foundation of my quest.
Like I told a friend when they said “WHY?” when I told them about my plan to control lighting via my cell phone, its the journey that real interest me, not the destination.
My blog is really by method of book keeping my activities so I can reference it later (In fact, blogging itself is a learning experience for me). If others find it useful or interesting all the better.
Thanks for your interest.
An Introduction To Rudimentary Criteria In “UBot”
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it up! I’ll go ahеad and bookmɑrk your sitе to come back in tҺee future.
All the best