problems with learning eagle

Thread Starter

1-3-2-4

Joined Dec 26, 2008
198
I've been trying hard but so far my projects have been simple but this program is hard.. I'm just trying to do a simple board with just 4 LED spots but I can't figure out how to do the first piece of the board.

Should it be this hard?
 

BSomer

Joined Dec 28, 2011
434
Sparkfun electronics has a tutorial series on how to use Eagle...
http://www.sparkfun.com/tutorials/108

There are also a number of tutorials on youtube.

Where are you getting stuck? Is it making the schematic or the layout of the board? When using eagle it may be better to start by making the schematic first. Then make the board from the schematic so the two are linked and there will be a smaller chance of errors when routing the board. Although human error still applies to the schematic. :)
 

MrChips

Joined Oct 2, 2009
25,919
We have a number of members here on AAC with lots of experience with Eagle.
Just tell us your problem and I'm sure we'll find the answer.
 

Thread Starter

1-3-2-4

Joined Dec 26, 2008
198
In my head I know the layout since I already did a mock up on a perfboard it's just the program and me have different ways of doing things..

I'm used to drag and drop type of layouts.. and last time I tried eagle I had a hard time.. however I did not do the schematic first but went right for the layout..

my design is very very simple.. 4 LED's would be on like a 2" x 10' board connected in series with a voltage regulator and a resistor.

That's the basic one.. I have another but it's a bit more complex and I want to just learn my way around first.
 

Thread Starter

1-3-2-4

Joined Dec 26, 2008
198
I'm stuck somewhat now.. I'm trying to do the LED's which are superflux Philips Lumileds however I don't seem them in the library nor do I see my LM2940T listed
 

nerdegutta

Joined Dec 15, 2009
2,684
If you cannot find your exact component, and you are not doing simulation, then find a component with similar footprint. And, oh yes, start with creating the schematic, then move on to the board layout, and place your components.

Do you have a pencil drawn schematic?
 

nerdegutta

Joined Dec 15, 2009
2,684
If you do that, we'll get a better idea of what you want to achieve. At least I will. Then maybe later today, when I'm finished at work, I might give it a try, in Eagle 6.2.0.
 

BSomer

Joined Dec 28, 2011
434
I have to admit that is one part of eagle that is sometimes a daunting task, trying to find that one component you need for your design amongst the hundreds of other stuff in the libraries. The search sometimes works flawlessly, other times not so well. When searching for a component I use an asterix before and after the part number and drop the letters in the number, i.e. *2940*. Then you can narrow down the results.

One other thing I noticed is the size of board you are trying to make. Depending on the version you have (paid or free), there are some limitations to the size of the board. The freeware version only allows for a board area of 4 x 3.2 inches.

I downloaded the freeware version of diptrace, though I haven't dug into it too much yet. Diptrace does not have a size limitation but instead has a limit on the number of pins, 300 I think.
 

Thread Starter

1-3-2-4

Joined Dec 26, 2008
198
If you do that, we'll get a better idea of what you want to achieve. At least I will. Then maybe later today, when I'm finished at work, I might give it a try, in Eagle 6.2.0.

here is a little quick one I did

the block on the left is a voltage regulator.

here is where I'm at now
 

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nerdegutta

Joined Dec 15, 2009
2,684
I've done some assumptions:

VDD > 12vdc
Regulator is LM7812T

LEDs are RED with:
Vf = 3.2v
mA= 20

With 4 LED in a chain you would give: 4 x 3.2 = 12.8v. Which is more than our power supply. Therefore I think it's wise to split them into two strings with two LEDs in each string.

With Ohms law we get:

2 x 3.2 = 6.4v
12 - 6.4 = 5.6
5.6 / 0.02 = 280R

Resistor = 280Ohms

Is this what you are trying to do?



Link to big view.

To smooth things a bit, you might want some caps along with the regulator. This circuit is not finished, but just as an illustration...

Comments on the calculations are welcome.:)
 

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Thread Starter

1-3-2-4

Joined Dec 26, 2008
198
Well the application is going in the car so I factored in 14.4V but I'm using a 12V voltage regulator on it.

I forgot to provide the specs of the LEDs :(

the vf is 2.5 it's rated for 70 mA but I'm driving them at 60 mA they are superflux red-orange LEDs.

I got around 33 ohms in my calculations
 
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