[tamu]

So I started learning how to use eagle. It was a bit hard first but then all became very easy.
 
Ive done some cmoy designs so far. here is the last one I made. I would like to know what you guys think and is there anything that I should be improving?
 
thanks for the inputs guys!
 

 

[nikongod]

Did you want to put the switch for power on the PCB? Just checking...
 
Also why only 9V? Just dont label it.
 
You have no Rled. Poof.... Do red LEDs emit red smoke (joke, and no they dont)
 
If you rotate the power input connection 90* you can shorten the power input traces significantly. Depending on what case you put this in it may allow for neater wiring too.
 
The trace from C1a to pin 3 can be shortened significantly by going directly to the op amp (between the opamp and those resistors) rather than looping all over the board.
 
If you flip the positions of c2a and r2a(? the 100K resistor next to c2a) you can shorten the trace from the pot to it, and avoid a few turns. This may also allow you better ground plane fill.
 
The trace from the pin 7 output of the opamp does not have to go under the pot like you did. Route it in front of the pot (between the pot and the front of the case...) After this, the trace from the front/center pin of the pot can be routed more directly to c1a 
 
Have you considered adding pads for small power supply decoupling caps right near the op-amps? 
 
edited:
on JP2 if you ground the center pin out towards the top (away from the opamp/resistors) you can get a more direct path from r3a3 (I think thats the part) to pin 3.

 

[Avro_Arrow]

Your input/output jacks and volume control may need to
be moved closer to the edge of the board if you want them
to be available outside of the case...

 

[amb]

Try running DRC and I think you'll probably find quite a few issues.

 

[tamu]

 
Nikongod I know rled is not on the board and the power was somthg I didnt really look into. I should avoid putting useless info on the board

 
Ill try turning it and see what happens. about the caps and resistors, I think the problem is that Im trying to put all the traces to one side of the board.. it was why I couldnt change the positions anymore. I thought it would be easier to develop the pcb as I never have done any. Thats also the reason why jacks and pots are a bit away from the edge.. btw all the routing was done by eagle. I saw I can do it manually but I thought it would take a loong time.
 
 
amb, I didnt even know what drc is till now and as you said its giving me heaps of errors.. its angles, some being off grid, no vector.. what do I have to do to fix them?
 
Maybe I can use wire under the board to connect the power or some other traces to their points. it could save some more space on top. Would this be ok?
 
thanks.

 

[Avro_Arrow]

It is usual practice, on a single sided board, to put the traces on the bottom
of the board and the components on top. Makes it easier to solder that way.
On a double sided board, the general rule is to put the traces running one
way on the top and the other way on the bottom (say left to right on bottom
and front to back on top). For your application, if you are going to use a
double sided board, put as many of the traces as possible on the bottom
and use the top as a ground plain. It is OK to put a few traces on the ground plain
side to jump over something if you need to. The goal is to keep traces as
short as possible.
Try to avoid sharp corners, use rounded corners. Keep traces the same width
all the way through the radius.
 
Hope this helps!
We'd love to see how you improve the design.

 

[tamu]

Thanks very much. very useful info. however I still need to learn and practice.
BTW having the ground on one side makes alot sense.  I still couldnt fully understand the functions in eagle. I think its gonna take a bit more fiddling.
 
Rounded corners; do I do it in the design rules or in autorouter setup screen?
 
also I totally forgot to add a switch

 
another thing that I was thinking is to remove the pot and jacks from the board and just put terminals or etc instead.
 
Will try to come up with a different one tonite. will do as much as routing on the bottom side and try to have them on one-sided board. if it becomes too messy Ill try having the ground on top side.
 
thanks again. much appreciated

 

[Avro_Arrow]

When you are in the main window, set your Trace Width and Miter to the same value.
If you want to practice, just start a new board with no schematic and practice with
the "wire" function. Sometimes it is faster to just do the whole project this way but
you will not have any cross check to your schematic.
 
Good luck! 
 
Quote:

Thanks very much. very useful info. however I still need to learn and practice.
BTW having the ground on one side makes alot sense.  I still couldnt fully understand the functions in eagle. I think its gonna take a bit more fiddling.
 
Rounded corners; do I do it in the design rules or in autorouter setup screen?
 
also I totally forgot to add a switch

 
another thing that I was thinking is to remove the pot and jacks from the board and just put terminals or etc instead.
 
Will try to come up with a different one tonite. will do as much as routing on the bottom side and try to have them on one-sided board. if it becomes too messy Ill try having the ground on top side.
 
thanks again. much appreciated

 

[tamu]

Sweet! will look into that too..
 
ta

 

[Avro_Arrow]

In a side note to your CMoy design...
It might be easier and just as effective
to use a TLE2426 in place of your resistor
divider and Op Amp virtual ground.
It uses much less power and is enough
for a single Op Amp like you have.
What you have is not wrong, it is just
more than you need.
 
Here is a CMoy I did last year.
The top layer is a ground plain.
All the signal and power traces
are on the bottom. I wasn't sure
what kind of case I was going to
use so I made a jacks off board.
The chip at the left is a Dip 8 TLE2426.
 

 

[tamu]

I picked the opamp simply because I already tried it and I have some cheap opamps. But as you said it just might be the best option for me. yours looks really nice and tidy..
After eagle I need to learn pcb developing too.

 

[cobaltmute]

Doing a PCB is an iterative process.  Place, route, decide it sucks, rip-up everything, place, route, decide some parts suck, rip them up, re-route. Repeat.
 
Try and reduce the cuts in your ground plane.  There is a few places I see where your ground plane is no better than a trace due to other traces causing bottlenecks.  You also have some traces that could be a lot shorter.  Take a look at pin 3 of OP1 for example.
 
I haven't tried to layout a single sided board, but if you look at the "professional" ones, they use jumpers to try and reduce the lengths of traces and cuts in the ground plane.

 

[tamu]

himm. jumper is a good idea too.
 
I guess I need lots of practice and also when I decide to make my pcbs then Ill know my capabilities better.
 

 

[cobaltmute]

http://www.alternatezone.com/electronics/pcbdesign.htm

 

[tamu]

Quote:

http://www.alternatezone.com/electronics/pcbdesign.htm

Thanks!