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Playing with 240V

Discussion in 'Electronic Basics' started by Ant_Magma, Mar 13, 2006.

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  1. Ant_Magma

    Ant_Magma Guest

    I want to test my switching PSU and my voltage regulator to see whether
    or not it produces my desired output.

    The input voltage is to be 240V 50/60Hz direct from the power outlet.
    I'm connecting the input of the PSU with the typical 3 pin plug
    connected to the outlet.

    1) Now, to connect the cable from the 3 pin plug to the PSU, is it save
    to run 240V on the humble breadboard?

    2) And is it ok to use normal wires as jumpers?

    3) At the input side of my circuit which experiences 240V, what is the
    conventional trace width is should use on my PCB? In my PCB program,
    i'm using 1mm for all my traces (size of the pcb does not matter)
     
  2. I don't think I'd want 240V on the usual white plastic breadboard (is
    that what you're referring to ?) Keep the power supply off the
    breadboard, and just run the DC output from it to the breadboard.
    1 mm (.040") traces are very wide, by modern PCB standards - I
    normally use .010" (0.25 mm) for most signal traces, and reserve
    larger traces for power distribution.

    For the 240V AC input, I'd probably use .040 - .050" traces, with at
    least .050" spacing (probably 0.1", if possible). (and use a fuse
    somewhere in the 240V!)


    --
    Peter Bennett, VE7CEI
    peterbb4 (at) interchange.ubc.ca
    new newsgroup users info : http://vancouver-webpages.com/nnq
    GPS and NMEA info: http://vancouver-webpages.com/peter
    Vancouver Power Squadron: http://vancouver.powersquadron.ca
     
  3. Ant_Magma

    Ant_Magma Guest

    Yeah, that's what i thought so too. I guess i'll probably use a
    connector or some sort to connect the power socket directly to the PSU
    then only take the output and connect it to the breadboard.

    I know 1mm is huge, when i printed it out my PCB was 1/3 size of an A4
    paper! But i just want to be safe =)

    Maybe i'll try with your recommended dimensions and see how much can i
    shrink it.

    How about the ground traces? I bet they have to be large also right?
     
  4. Chris

    Chris Guest

    A couple of things, Ant:

    * If you're posting from Google Groups, click "Show Options" on the
    title bar of the post you're responding to, and then click reply.

    * Leave some of the post you're responding to _above_ your post, so
    people who have other newsreaders can see the context of what you're
    saying. It's not necessary to have everything (especially if it's an
    involved conversation), but you should use proper nettiquette and leave
    something. You'll notice that everyone responding to you does this.

    * .040 traces are OK for line voltage that's going to be at low
    current. There's only a few of them -- you can afford to be generous.
    Leave .2" between traces if you can for more safety.

    * Line Ground traces are _always_ the same size as line power traces
    for obvious reasons. In the event of a fault, you don't want the
    ground trace to fuse.

    * All your non-power traces on the 5V side should be .010" default if
    you're having a board house do your board.

    * Be sure to take board house delivery times into consideration. Pay
    the premium price to get something delivered NOW.

    Two weeks ago you mentioned you had two months left for your college
    undergrad senior project. I'd assume (like at nearly all colleges),
    you need a passing grade in the project to graduate. There are now
    only 7 weeks left (assuming this isn't just an elaborate series of
    troll posts).

    You're out of time. Considering your investment of time and money in
    four years of college, you really should get a little more serious
    about getting things going NOW. Spending a couple of days waiting for
    an answer to one or two questions on the newsgroups is not efficient.
    It's actually counterproductive, because it gives the illusion that
    you're doing enough and working fast enough. You're not.

    As mentioned before, your most logical route to passing this course is
    hiring an undergrad senior or graduate student who has some real world
    experience in electronics and particularly network interface hardware
    and software for some intensive tutoring and kibbitzing on your
    project.

    A couple of dozen hours of help from someone who has experience is all
    you need, if you've done well in your classwork. From your posts, it
    just seems you just have very little or no practical experience in
    electronics outside the classroom. At $40 USD per hour, that $1K will
    be a good investment in your education. If you can't swing that, have
    a talk with your parents or borrow the money. You've gotta do this
    before you're really out of time. Another couple of weeks, and you
    won't be able to find anyone who help you under that kind of time
    pressure -- they'll have their own problems to take care of first.

    Waste anything but time (an old NASA motto from am older SF movie, I
    believe).

    Good luck
    Chris
     
  5. you mentioned using 0.040" traces for the high voltage at low current
    and using 0.010" traces for the 5V traces.

    Is there a way of calcuating the track width based on the current it will
    carry?
    I know this will depend on the copper of the board and its thinkness but,
    any
    ruff method for getting a good idea of what track sizes to use for different
    currents.

    Thanks
     
  6. Chris

    Chris Guest

    Wider traces for the line voltage is customary, as well as placing the
    line voltage traces as far apart as possible, within reason. Usually
    you've only got a couple -- I guess you could be stingy if you have to.

    Logic signal lines don't carry any current to speak of -- I'm used to
    using .010 for board house work, and .020/.025 or so if I'm etching the
    board myself. Again, just custom.

    If you google "circuit board trace width calculator" (no quotes),
    you'll come up with many different ways to punch it in:

    http://www.mgchemicals.com/products/popup/calc-pcbtrace.html

    I believe I've used this one. Be sure to watch temperature rise.

    Good luck
    Chris
     
  7. Ant_Magma

    Ant_Magma Guest

    Yes i remember you giving me the advice. I understand this might be
    common in universities overseas.

    Unfortunately, in my university paying a graduate student to help is
    not common here and furthermore i don't believe there are any graduate
    student which has worked with powerline communication, mostly
    theoretical.
     
  8. Ant_Magma

    Ant_Magma Guest

    Yes i remember you giving me the advice. I understand this might be
    common in universities overseas.

    Unfortunately, in my university paying a graduate student to help is
    not common here and furthermore i don't believe there are any graduate
    student which has worked with powerline communication, mostly
    theoretical.
     
  9. Chris

    Chris Guest

    Ant_Magma wrote:
    take care of first.
    You might want to contact your senior projects teacher or department
    adviser, if you need help.

    Chris
     
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