pcb layup problems

Discussion in 'The Projects Forum' started by fran1942, Sep 26, 2011.

  1. fran1942

    Thread Starter Member

    Jul 26, 2010
    58
    0
    Hello, as an electronics beginner. I am putting together my first PCB.
    I am having real problems however getting all the components connected in the Altium software package.
    The main problem lies with the two Picaxe microncontrollers I am using. They each need a smoothing capacitor across their power supply plus their pinout tracks. I am just getting all tangled up. The four diodes have to be in the positions they are. Everything else can move around,.
    Can anyone suggest a layout strategy or any tips that might enable to get this completed ?
    Thanks kindly.
     
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  2. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,809
    834
    Can you make a two-sided board and use the second side as a ground plane? If so, make your ground connections via a thermal pad, to make soldering easier...

    The second side can also be used to route short traces that would get in the way of another trace if you were limited to one side.

    It also looks like some of your transistors are too close together and will not physically fit on the board.
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
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    You could swap to a dual layer board. I also think the two PIC AXE unit can share a decoupling cap if they are placed close together. Use standing/upright resistors. Also if you can do it. Swap around the pins used on the PIC AXE to solve routing problems. Add some zero ohms resistors as jumpers. You may also consider two boards stacked on each other. If you can not have dual layer PCB. Post your project files and I may take a look if my times permit
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Gee, fran1942 - I'd made a number of suggestions to you in this thread:
    http://forum.allaboutcircuits.com/showthread.php?t=59077&page=2
    but it appears as if you decided against using any of them.

    I'm curious, did you try any/all of those ideas and had problems, or did it/they confuse you, or did you just not feel like trying any of them?

    As far as the speaker in your schematic, I had to assume that it was a typical 8 Ohm magnetic version. If you connect a low-impedance/low-resistance load to your PICAXE without blocking DC current, you risk burning up your I/O pin. Max I/O current is 25mA per pin; so at 100% duty cycle (steady ON) with a supply of 5v, the minimum load resistance is 200 Ohms.
     
  5. t06afre

    AAC Fanatic!

    May 11, 2009
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    Please post pdf files. Not blurry bitmaps. Why are you using two resistors on pin 3 on each controller. You may drop all of them. Also what is the thruth table for the 4 LEDs. You use two outputs to controll 4 of them. Can this be simplefied. As you have some free outputs you may use. It is not easy to see due to the blurry picture.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    I actually prefer .PNG files; they are compact like .jpg files, but are not "lossy"/fuzzy like .jpg files are, and don't require extra software to read.
     
  7. t06afre

    AAC Fanatic!

    May 11, 2009
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    PDfs file from most ECAD systems. At least a professional one like Altium Designer. Will be vector based, with scalable fonts. So they can be zoomed up to any format without any blurring at all. Before Adobe pro was needed to make PDF files. But now you can get a free alternative for all OS. And well hmm... a person with interest in electronics without a PDF installed on the computer not very likely.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    I hear you - but with as many people as I try to help on here, I simply don't have the time to be downloading everyone's PDF file to my computer to look at them, and wait for Adobe Reader to load. It simply takes me extra time, extra steps, and I wind up with more clutter on my computer.
     
  9. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,392
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    QFT.

    [rant]
    But even thumbnails gets confusing, just embed the dang things into your post so I don't have to flip back and fourth between tabs. Space the text so I can read what is relevant to a picture while I can see the picture.
    [/rant]
     
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