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Is this circuit correct??

ByPaul

 

I have made a Picaxe 28 board circuit. i dont know if its correct please help me correct it.i made this circuit using DesignSpark PCB. This is my first time making a circuit board.I would also like to buil this PCB myself. I have refferd to some tutorials on making homemade pcbs but am confused ,in some they say dont use sand paper while in others use sand paper nd all Am really confused. can anyone plz suggest me a good tutorial.This is my circuit-


IMIM board 

 

The thin yellow lines are the ones which i will connect on back of the board using wires so that i wont need to make a second layer.. nd i would like to place i2c chip to it,but thats nt important.. 

 

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bdk6's picture

Take a look at this.  It will teach you all you ever need to know about PCB layout.

http://letsmakerobots.com/node/36773

 

Duane Degn's picture

Does DesignSpark let you start with a schematic and then convert the design from schematic to PCB? If so you should learn to use it. If not, get a different PCB design program.

I really like Diptrace myself. The free version has a few limitations but I bet the limitations wouldn't be a problem on this board.

After seeing how easy it is to have a PCB made by OSHpark.com and other fab houses, I've given up trying to make my own at home. It's so much easier just to send the gerber files to the fab house and get the boards back a few weeks later.

One thing I've learned is that traces shouldn't turn at 90 angles like you have them on your board. I think you could get away with it most of the time but apparently 90 degree turn can cause etching problems. They can also cause problems with high speed signal lines. 90 degree turns apparently don't look good to a lot of people (I think they get used to seeing 45 degree turns so the 90 degree ones look wrong). If you look at PCBs you may have, you'll probably see turns made up of multiple 45 degree turns.

It also looks like the yellow traces (on the back of the board right?) are very thin. How wide are your traces. In general it's a good idea to have traces relatively wide unless you need them to be thin to get them to fit. 0.010" seems to a common size and should be okay for signal traces. Power and ground traces should be wider.

It's often a good idea to have all the traces on one side of the board going in the same general direction. For example, you could have the top traces travel up and down the board while the bottom trace travel left to right. Use a via to change sides of the board when you need the trace to change direction. This helps a lot in keeping the traces to look neat and tidy.

Most ICs should have a decoupling capacitor near their Vdd pin. 0.1uF seems to be the most common value for decoupling caps. They're cheap if you buy a bunch at a time.

As other have said, you're not likely to find someone willing to go over your board to make sure all the traces go where they're supposed to go but you will likely find help if you have a specific question about how to connect a component. You're also likely to get suggestions on ways to improve a PCB layout.

I've posted several of my early layout on a different forum and received all sort of useful advice on how to make a better PCB.

BTW, I've found layingout PCBs get a lot easy after you've done a few.

Paul's picture
I didn't use any schematics. I jst saw a sample PICAXE 28 pcb design from picaxe website and modified it. But in the sample pcb there is no second power supply connection so am not sure if my connection is correct. I will post a better pic.. Sorry
OddBot's picture

Even if you post a better pic it's pretty well useless. 

The schematic diagram is very important.

bdk6's picture

What did you go by to lay out the board?  If you did the layout from a schematic only in your head, I can almost assure you it will be incorrect.  Did you not have anything to go by?  And without something to compare it to, how can anyone say if it matches or not?

OddBot's picture

1. How do you expect anyone to verify this circuit when you have not posted a schematic?

2. Assuming you do post a schematic you want someone to check every single trace on the PCB???

3. If some kind soul does offer to check every trace on your PCB then the least you can do is attach a high resolution version of your PCB layout so that they won't need a magnifying glass.

 

I am not trying to be cruel but you really need to think your questions through better. The help we offer is only as good as the information you provide.

Paul's picture

am not sure if i have connected the V2+ line correctly..