Perfboard Wiring

Discussion in 'General Electronics Chat' started by camon, Mar 9, 2012.

  1. camon

    Thread Starter New Member

    Feb 3, 2012
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    Hi everyone,

    I am building a circuit and i'm going to use a perfboard to implement it. I'm a bit confused with perfboard wiring. The thing is my circuit runs at 14v max and it will never pass over 20amp. My circuit has lines that crossover so in my perfboard i'll have along with the soldering and components, some external wires to do the crossover and also to do some long lines that connect two components. The confusion is for this current can i use 0.6 mm cooper wire that fit on the holes of the breadboard?

    Basically i'm confused how wires can handle the current of my circuit (or any circuit) :S and what the diameter and type of wire (solid or stranded) has to do with that :S

    Please someone can enlighten me?
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,437
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    20A is a lot of current. You will need 12AWG wire for that.
     
  3. jimkeith

    Active Member

    Oct 26, 2011
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    99
    For a reasonable temperature rise, I would not run more than 4A through 0.6mm single copper conductor--a 20A current rating will take (5) parallel conductors--for ease of wiring go with solid conductors--use bus wire that has no insulation or magnet wire that has very thin insulation that must be scraped off prior to soldering.

    The best ampacity chart I've found is this: http://coonerwire.net/amp-chart/
    0.6mm is roughly AWG23

    The ampacity of fine wire is a grey area as it depends upon the type of insulation used--since this size is not used for power distribution, the ampacity is not clearly stated--for transformer application, the current rating is generally in the range of 500 to 1000 circular mils per amp--this puts the current rating at about 1A--however a bare conductor that is exposed to air will have a much higher current rating--fusing current (melting) will be in the order of about 30A for this wire size.
     
  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    That kind of current has nothing to do on perfboard if you ask me. It will be ok to have the control logic on the perfboard. But the high power part should be run all the way on separate cables with adequate dimmension. All the way from the power source to the end point. Remember with 20 A current. Proper connections will also be important. Particularly if this is a low voltage system
     
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
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    You said Perfboard then you said Breadboard. They are very different. Which are you using?
     
  6. #12

    Expert

    Nov 30, 2010
    16,269
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    I think t06 has the right idea. Some of my early perfboard work is frightening to consider because I tried to go onto the board with screw terminals, switch the power, and then come off the board with screw terminals. There just isn't enough strength in a perfboard.
     
  7. jimkeith

    Active Member

    Oct 26, 2011
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    I use fiberglass perf board and have run currents up to about 30A without problems--only watch for ground loops where you may be measuring low voltages in high current circuits
     
  8. camon

    Thread Starter New Member

    Feb 3, 2012
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    0
    ok i said that it never exceeds 20amps. So suppose that it does not exceed 16amp. I have a pcb relay rated 12v and that supports 16Amp (http://www.findernet.com/en/products/families/18/series/40). So if the perfboard can't handle 16amp how can i connect the power wire that i want to join/cut using the relay? the relay is soldered to the perfboard so were do i put the wires?!

    if i understood correctly i should have the main core components of my circuit that work with low current wired in the board with small diameter wires no problem there, and the circuit part that connects to the high "amped power" should be interfaced with screw terminals in the perfboard. That is for the relay case i should have terminals that connect to the relay poles and then use a wire with larger diameter to handle the 16amp and connect that to the terminals?
     
  9. Wendy

    Moderator

    Mar 24, 2008
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    If you must use the PCB, use extra heavy wire for the current carrying wires. But then I think someone has already mentioned that.
     
  10. camon

    Thread Starter New Member

    Feb 3, 2012
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    0
    Ok and i can solder them to the perfboard through multiple holes or is that a problem?
     
  11. jimkeith

    Active Member

    Oct 26, 2011
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    99
    Sounds good to me--just look for and reinforce high resistance bottlenecks and solder bus wire along any such trace
     
  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    Don't run the high current wiring on the control board! :eek:

    Run the 20A wiring through relay fuse, terminals etc as point to point wiring using a heavy gauge wire.

    Then put the low current control electronics on the perfboard.
     
  13. Wendy

    Moderator

    Mar 24, 2008
    20,765
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    I have done both. Soldering a wire onto a trace will buck it up so it doesn't smoke, but in general you are better off keeping the high current stuff off the board.

    The reason is simple. High current tend to generate big pulses in odd places. You also get odd magnetic coupling due to the high currents. If the current is constant it isn't as much of a problem, but if it turns on/off much there will be a lot of noise in the environment, some of it where you never expected.
     
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