Help with PCB design... I'm becoming insane! Please help!

[TheKrieger]

I'm a new to PCB design and after reading several articles and books, I felt pretty confident at designing my circuit in software. I have tried using Eagle, Orcad and Proteus; but have failed in epic proportions. I'm not designing something awfully complex:

-This circuit is connected to the power supply of 120VAC so I need to use a Transformer to lower the voltage.
-The microcontroller takes inputs from external devices, meaning that I need to use connectors.

Now, here are the problems I'm facing:
-I haven't found a way to put the transformer in the PCB! In CAM software they're always a generic type and I'm unable (or at least haven't found how) to fix the size or values of it. Do they need to be outside of it? I don't think so, I have seen many PCB's with embedded transformers.
-What about the connectors? I don't seem to find the ones I need, there's even USB connectors but not a single AC male connector for energy supply. I have some PCB connectors from specific manufacturers, which I'm gonna use for manufacturing; where can I find them? Do I need to do custom components? How the hell do I do them??? I can't find accurate info about it anywhere!
-Why can't I find some components in SMT or TH package? I have seen those components in both technologies.

Can you help me out? Have you faced those problems before? If you haven't, could you give me some orientation towards a great book or tutorial on PCB design for manufacturing (for Eagle or Proteus)?

Thanks in advance

 

[BobK]

PCB CAD packages have the capability of creating your own components. This is what you have to do for anything that is not in the library. Look through the documentation for your software to determine how to do this. I tried Eagle and found that facility very confusing. I have also used the proprietary ExpressPCB software which is beautifullty simple and easy to use, but can only be used to order PCBs from ExpressPCB.

Basically, to create a component, you are going to draw the outline of it, add pads and connect those pads somehow to the pins on the device in the schematic.

Bob

 

[jackorocko]

To add to what bob said, you will find all the necessary measurements in the datasheet for the component you are trying to draw.

So more or less you need to know all your components prior to making a pcb and you need to stick to them unless you can find a replacement that is a perfect fit.

 

[OLIVE2222]

Indeed you need to learn you to draw your own footprint with your CAD package as the "standard" footprint library will may not fit your needs.
But before drawing your footprint you can have a look on the web by using query like "eagle PCB library" and you will find toons of them. Another sourceof libraries are the components manufacturer themself, again check the web.
To be noticed that sometime you have all the component package measurments in the datasheet but not the footprint layout who can be in an another document or even be defined by standardized rules.
The same component can also have a different footprint depending on the PCB density and/or the number of layers (pads for dual layer can be smaller). Generaly when you draw the schematic the software allow you to assign a corresponding package, including one of your own, assuming you change the file path.
If you don't have the datasheet of your transformer, just measure it with a caliper. Pads hole must be a little wider then the pin diameter to compensate manufacturing tolerance. The pad diameter must be (as rule of thumb) around 2 time the hole diameter. When all needed footprint are there it's recomanded to create a library with them. At the end of the process print out your layout at 1/1 scale and place al the never used before component on it for check purpose.
goog luck,
Olivier

 

[TheKrieger]

Thank you all for your responses, but is there any straightforward tutorial or book that can help with making custom components? I have tried several time doing them but I only end with a lot of errors and badly done components.

 

[OLIVE2222]

I suggest to google a bit with query like "Eagle library tutorial".
I don't know which cad you decide to go for, eagle just looks very popular.
Indeed such software's can be hard to learn but for simplest projects, design libraries is probably the only obstacle.

Olivier

P.S. I use Altium 6, the reason why I can only give you generic advices.