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Software => Software => Topic started by: donggyu on September 22, 2010, 04:47:19 PM

Title: Noob Eagle CAD Questions
Post by: donggyu on September 22, 2010, 04:47:19 PM

I think I might want to start designing my own pcb boards, and I have a some questions:

-Why do you people design pcbs and send it to a fabhouse where they make it for you? What does the fabhouse do?

-What is the arrow symbol in the green/red schematic? Why are the grounds often not connected to anything?

Thanks!

-Donggyu

Title: Re: Noob Eagle CAD Questions
Post by: Ro-Bot-X on September 22, 2010, 05:19:42 PM

You should read the SparkFun Beginning Embeded Electronics tutorials:
https://www.sparkfun.com/commerce/tutorials.php (https://www.sparkfun.com/commerce/tutorials.php)

Title: Re: Noob Eagle CAD Questions
Post by: donggyu on September 22, 2010, 07:37:37 PM

Thanks! My question relating to the arrow symbol and the fabhouse is still unanswered though. Can you please explain it to me?

Title: Re: Noob Eagle CAD Questions
Post by: rbtying on September 22, 2010, 10:50:35 PM

Arrows are usually GND, as the CAD program will connect the GND and VCC for you.

Title: Re: Noob Eagle CAD Questions
Post by: donggyu on September 23, 2010, 01:23:49 PM

So the arrows AND the traditional ground sign is GND? Confusing..

Title: Re: Noob Eagle CAD Questions
Post by: rbtying on September 23, 2010, 02:46:49 PM

Which arrows are you talking about?  Normally the one that seems to point off into nowhere ( ->) is GND, as the CAD program connects those.  I'm not really aware of other arrows.

Title: Re: Noob Eagle CAD Questions
Post by: Razor Concepts on September 23, 2010, 03:30:59 PM

From my experience arrows typically face upwards and indicate VCC

Title: Re: Noob Eagle CAD Questions
Post by: galannthegreat on September 23, 2010, 04:50:26 PM

Here's a picture that shows some of what you mean. (there are other symbols, but these are some of the most commonly used, though I am familiar with with the up arrow as Vcc, don't know why it isn't here)

Title: Re: Noob Eagle CAD Questions
Post by: donggyu on September 23, 2010, 05:03:35 PM

Oh ok. What is the difference between a signal ground and a power ground?

Title: Re: Noob Eagle CAD Questions
Post by: Ro-Bot-X on September 23, 2010, 05:37:42 PM

Quote from: donggyu on September 22, 2010, 07:37:37 PM

Thanks! My question relating to the arrow symbol and the fabhouse is still unanswered though. Can you please explain it to me?

The other members answered tour arrow question.

We send the boards to the fabhouse because they can fabricate them cheap. For instance, 10 boards up to 5cm x 5cm are $20 to make. If you can do one board in one hour at the quality of a fabhouse for $20 then do it by all means. I would pay myself to do it at least $10 per hour, as it will not have plated holes and solder mask. To make a board you need tools, like a drill press capable to hold and drill with tiny bits, a laser printer for the toner transfer, chemicals to etch the board, then again toner transfer for a silk screen. Not worth it in my  opinion. If you only want one board, go to BatchPCB at SparkFun and get it for about $15.