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Drawing the Schematic for the Desulfator in Kicad.

The Desulfator Schematic in KiCad

The Desulfator Schematic in KiCad

HAPPY NEW YEAR! Usually this time of year I think about what I accomplished in the last year and also where I want to go in the next one. I have been so busy this season that I really have not given it as much thought as usual. However, I will write down a few things I have been considering for this blog.

1: I will complete the metal brake as far as I can take it. The brace is currently being constructed. I hope to weld a few more parts later tonight. A post will be coming out very soon.
2: The Desulfator is progressing… that is today’s post.
3: Electronics theory: The next theory post will be about Field Effect Transistors (FET and sub types JFET, IGFET, and MOSFET). By that time we will have touched upon a lot of components and I think it will be time to actually design some circuits for them.
4: Software: We will learn several pieces of software useful in analyzing an Electronics design. Where possible I will try to find open source software that runs on Mac, Linux, and Windows. However, there may be a few cases where it has not been ported to Windows. Open source is the main goal, I don’t think most of us really want to spend hundred’s of dollars on a hobby we may only use a few times.
5:  Aquaphonics / Hydrophonics:  I have been doing a lot of reading about these subjects lately.  I am really about out of time on a day-to-day and I am looking at a way to grow some of my own food.  Besides, they are a process and processes always interest me.  Very soon I will be creating a post about what I have learned so far.

Today’s post is about some software to create Printed Circuit Boards (PCB), Kicad. As I described back in the post “A Lead-Acid Battery Desulfator – a reason to learn KiCad”  I am using an designed circuit to learn Kicad.  There is three Electronic Design Automation,EDA, pieces of software available: Eagle; GEDA, and Kicad. Eagle is probably the most popular, but it is proprietary. They have a free version available for all three operating systems. However, the free version limits the PCB size and it cannot be used commercially. (We might become so good at this we can sell something.)  GEDA is only available for Linux and Mac. That left me with Kicad, but I think it is a good choice anyhow.

Kicad opening screen.

Kicad opening screen.

Kicad is actually a software suite and the opening screen simply brings up icons for those programs.  The programs are called:

  • Eeschema, a schematic editor.
  • Pcbnew, a printed circuit board editor.
  • Gerbview, a GERBER viewer.
  • Cvpcb, a footprint selector for components association.

Those are 4 of the 5 icons showing up on the opening window.   The 5th icon is Bitmap2Component and is used to put a Logo or some special symbol on the PCB.  Eeschema is the one we will be talking about the most in this post and possibly the next post because that is as far as I have done so-far on the Desulfator.

This is not a tutorial, I will provide some links to those at the end of this.  All I am doing is describing kind of an overview and some of the difficulty I have had so far.  The biggest problem I have had so far is “wrapping my head” around the steps.  I cannot learn software like this by reading the manual and have to train myself through my fingers by actually doing something.   When I started the program I was overwhelmed because I had no idea where to start.

The first thing you will have to do is either select an existing project or create a new one.  For the first project it will be necessary to create one.  Once you do that all the files associated with a project will be placed in that folder.  Normally the next thing you will do is create a schematic of what you want to build.  The schematic creates a human readable form, but it also creates networks of how components are connected together as well as a bill of material or list of parts,  Since the design already came with a schematic it felt like a step backwards to create a new one, but it was necessary to get it in a form the rest of the programs can use.

The schematic editor has three toolbars.  The toolbar to the left has about 5 icons.  Those are used to change the way the program works.  The toolbar on the top is used to run other programs associated with the editor;  things such as the part editor and the list programs as well as saving the file and of course, the all important undo button!   Each icon has a tool descriptor that pops up when you scroll across it.   The toolbar to the right are the actual tools used to place wire, buses, and components on the schematic.   Again, each icon has a tool descriptor.

The component library.

The component library.

Once in the schematic editor the first thing I recommend is place all the components on the drawing.   You do not have to have them located at the correct place yet… just get them on the screen.   The component I show in the picture is the one that gave me the greatest problems.  If you look at the picture closely pins 1 and 8 are greyed-out.   I attempted to connect them but ended up with errors.   I eventually had to copy the component into my own library and edit it with the additional pins.  Once you place one component of a particular type continue to add all of that particular type.   (i.e. resistor).   Once you are done putting them all on the page zoom in by using the mouse roller, and then edit the Field number and value.

Next move the biggest component into a convenient place and start the process of adding wires. and placing the other components.   It is a process that will take some time but you will get quicker as you continue on.   The videos I will link talk about using the hot keys.  Eventually I will use those, but for right now I wanted to just use the slow method with the mouse and just memorize what I needed to get the job done.

 

Error check

Error Check Screen.

Once you think you have it wired correctly press the electric rules check icon at the top and it will tell you about pins left unwired, etc.   All I can say is keep poking and hoping and go to the documentation until you get it figured out.   That is exactly what I had to do.   Eventually I got it to zero errors.   One of the things I had to do was add the battery to make it happy but the battery is not really part of the final circuit.   That is one of those “I will cross that bridge when I get to it” kind of things.

Once you have completed the schematic you can do several lists by pressing the net list button.   In the future, we will create a spice list for an actual design, but that will be much later.  The main list for right now is the Netlist.  Netlist will be used by CVpcb to attach a footprint to the components and later by PCBnew to create the actual PCB.

I wish I could give you much more detail and a set of step-by-step buttons to press to get the job done, but this program is way too complicated for me to do that.   However, others already have.

I have a whole bunch of links here to get you started.   Learn well… you may have to teach me.

filelist_size

A list of the files created. Notice all the files are very small.

The KiCad Overveiw page

KiCad Documentation:

KiCad tutorials both textual and visual.

The video tutorials that look to me to be the best.

Good Luck… it is a pretty big learning curve, but I think it will be worth it.

 

 

 
Note: The circuit design is not mine. It comes from an article on the web called Lead-Acid Battery Desulfator, by Alastair Couper and is from Home Power #77 of June / July 2000.

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Progress on the Desulfator.” by Create-and-Make.com is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

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