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Couple of noob questions

Discussion in 'Electronic Basics' started by [email protected], Dec 6, 2005.

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  1. Guest

    Hi all,
    I've gotten into electronics thanks to a class I'm taking (only took
    until grad school to find out that I enjoy this stuff :)) I've just
    built my first microcontroller project and am trying to get myself
    outfitted to do electronics work at home. A couple of questions:

    * What's the best way to solder to a DB-25 parallel port connector?
    I've done it successfully, but made a horrible mess of things. I
    started with some stranded 26ga (I think) wire and stripped off about
    1/4" from the end, then put it in the little hold on the back of the
    pin, got out the soldering iron, and made quite a mess. Is there a
    good way to hold things in place for this operation?

    * What's the best way to do home made PCB boards? Clearly breadboards
    and wire wrapping will only take me so far :) I've seen the toner
    transfer method and a couple of others. What's the easiest one to get
    started with? I have access to either laser jet or ink jet printers...

    * Are there any stores in the DC area that sell electronics components?
    The local Radio Shack is terrible and I feel guilty taking a diode or
    two from work.

    Thanks for any advice!

    Dan Lenski
  2. Puckdropper

    Puckdropper Guest

    wrote in

    Good heat transfer, a clean tip, and lots of practice. I usually go from
    one direction to another, either right to left, left to right or middle
    outwards. You'll mess a few of these up before you get it down.


    I don't know about the DC area /per say/, but there's lots of
    mail/internet order places around. Radio Shack recently (last 5 years)
    has focused mainy on consumer electronics, so mail/internet may wind up
    being your best/only option.


    Old computers are getting to be a lost art. Here at Uncreative Labs, we
    still enjoy using the old computers. Sometimes we want to see how far a
    particular system can go, other times we use a stock system to remind
    ourselves of what we once had.

    To email me directly, send a message to puckdropper (at)
  3. Dan Lenski

    Dan Lenski Guest

    Thanks for the tips!
    Thanks, I've ordered a few things from Jameco so far. The trouble is that
    I don't have a good "spare parts box" yet... so if I suddenly decide I
    need a 74190 IC, I have to wait a few days or pinch 'em from the lab.
    Perhaps I ought to buy a couple of those big component assortments from

  4. Rich Webb

    Rich Webb Guest

    Without solder. Look for the connectors that use crimp connections, like
    these that crimp
    onto a ribbon cable (commonly called IDC for Insulation Displacement

    Or the kind that crimps individual wires like these from Jameco You'll need a
    proper crimp tool, though. I like my ol' AMP Service Tool (p/n 696202-1)
    for this.

    Get one of those alligator-clip jobbies commonly called a "third hand"
    tool. A small, inexpensive bench vice is handy also; doesn't have to be
    terribly large, since most of what you'll probably be working on is
    relatively light weight.
    The prototype boards with "three holes per" are probably the quickest
    and easiest for one-off items. Even perf board without solder pads will
    work; just solder to the component leads.

    The toner transfer method is probably the easiest for at-home etching
    but there are also lots of commercial sources for low quantity prototype
    runs that aren't terribly expensive.

    See the message <> in the thread "Which is
    the best hobby do-it-yourself method for making PCB's?" (actually, read
    the whole thread).
    Mail order. Digikey. Or Jameco, Mouser, Newark, MPJA, AllElectronics,
  5. I find the best way is to not solder them at all by using DB connectors
    designed to use crimp-on pins. You strip the wire, crimp on the wire
    and insert the pins into the DB connector shell in the correct hole.
    You will need a crimp tool and extraction tool designed for the pins
    you'll be using. You can use simple hand crimpers which cost $20 or a
    crimp tool that holds the pin for you, crimps both the wire and
    insulation at once, and are controlled so you can't over or under crimp
    the pin for $100+. Two of the reasons I prefer the DB crimp connectors
    are that there aren't any exposed wires on the back of the connector and
    the shells can easily be re-used by simply extracting the pins.

    If you must use solder DB connectors, there are a few things you will
    need to make this a lot easier. First, you need a good soldering iron
    with a small enough tip that you can easily contact just one pin at a
    time. If you plan to do much electronics work you should invest in a
    temperature controlled solder station with interchangeable tips.
    Second, you'll need some type of vise to hold the connector so you can
    use one hand to hold the iron and the other to hold the wire. Third,
    you will want some small (1/16" or 3/32") heat shrink tubing to insulate
    the pins after you solder them. You will want to use 22 to 24 AWG
    stranded wire for DB connectors whether you use solder or crimp-on

    Now for technique. First, strip the insulation from the wire (1/8" or
    so), tin the ends and slip a short piece of heat shrink on each wire.
    Then fill the solder cups on each pin in the DB connectors you will be
    connecting wires to with solder. Then heat the connector pins until the
    solder re-melts and slowly insert the pre-tinned wire in being careful
    to get all the wire strands in the pin cup. While holding the wire
    steady, remove the soldering iron and allow the connection to cool
    without moving it. Then slide the heat shrink tubing down the wire,
    over the pin and apply heat to shrink it in place.

    Good luck with electronics.
  6. Steve

    Steve Guest

    The trick to doing this without needing three hands is to
    tin both the wire and the solder cup first, then reflow the

    Tin the wires. Unreel six inches or so of solder and bend it
    so it sticks up vertically from your bench top. Now you can
    hold the iron in one hand and the wire in the other while
    you tin the wire.

    Hold the connector in a small vise (Panavise or similar.)
    Partially fill the solder cups with solder. Hold the wire
    against the cup and touch the cup and the wire with the tip
    of your soldering iron to reflow the solder. There should
    be a tiny bit of solder on the tip to aid in heat transfer.
  7. Bob Monsen

    Bob Monsen Guest

    On Mon, 05 Dec 2005 17:57:30 -0800, dlenski wrote:
    <soldering DB25s>

    I bought some stuff from these folks:

    You can also buy those angle connectors directly from digikey, but you
    then need to make a PCB to use them.

    Bob Monsen

    The concept of fiction was nowhere in Mike's experience; there was
    nothing on which it could rest, and Jubal's attempts to explain the
    idea were so emotionally upsetting to Mike that Jill was afraid that
    he was about to roll up into a ball and withdraw himself.
  8. Pooh Bear

    Pooh Bear Guest

    You need to 'tin' the stripped wire before placing it in the solder buckets
    of the connector.

    I'll bet that makes a *huge* difference.

  9. Jasen Betts

    Jasen Betts Guest

    strip half an inch twist it, put some solder on it, trim it back to about 1/8"
    or less and then solder that into the little pocket.
    I still use stripboard
    I don't know of any in that area, but I have found the yellow pages to
    be helpful. "electronic component suppliers" is the category to look under.

  10. Your method wastes time and materials. You need to learn how to do a
    better job when you solder. Just strip it to 1/8" and tin the wire.
    Remember to touch one side of the wire with the hot soldering iron and
    apply the solder to the other side. Do not apply the solder directly to
    the iron or you will burn away all the flux which will cause bad looking
    solder joints.

    As far as holding the connector, I like to plug it into a mating
    connector mounted on a metal bracket, or clamp it gently in a drill
    press vise. Small ones are under $10 in a lot of places. These are good
    for holding the bare wires for tinning as long as you don't close the
    jaws too tight.
  11. Bob Masta

    Bob Masta Guest

    On 5 Dec 2005 17:57:30 -0800, wrote:

    Complete tutorial with hints and tips about the direct felt-tip
    method at:

    Best regards,

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Home of DaqGen, the FREEWARE signal generator
  12. That is way too much bare wire. I usually strip about a tenth inch.
    And carefully rewrap the strands so that fit the solder cup.
    Fine solder (.031 or .020 inch diameter, activated rosin core, 60% tin
    40% lead, or 63 % tin 37% lead). Narrow, but short tip on a
    temperature controlled iron also helps. Too hot, and the wire
    insulation melts back and the rosin burns off. Too cold and the
    solder doesn't flow well. Here is an example of a low cost one:
    and an even lower cost one:
    You can stick the metal case of the D connector to a magnet from an
    old speaker. Or get a small vise:

    Then the trick is to use something like an alligator clip
    on a flex joint to hold the wire in the cup, so you have two hands to
    operate solder and iron.

    But eventually, you will probably develop the dexterity to hold the
    wire between two fingers, and the solder between a thumb and finger on
    the same hand.
    I'll leave this for the moment. There have been some good threads on
    this subject ,lately, that you can look through with Google Group
    You may discover why we love Digikey and Mouser. They both have
    lovely detailed paper catalogs and good web sites with search
    capability. Mouser has no minimum order, and Digikey allows you to
    choose first class mail postage for small items.
  13. JeffM

    JeffM Guest

  14. noti

    noti Guest

    You could get a "Helping Hand". The best way to solder stuff is

    1) Get a good soldering iron. Preferably a Metcal, but at least something
    thats ESD safe, heat controllable and designed for electronics work. Make
    sure you have a good, appropriate sized tip.

    2) Have the appropriate tools, including: helping hand, vise, flux (good
    flux, not crappy RS icky golden crap), solder wick, good soldering iron
    (see above), tweezers, pliers, brushes, isopropyl alcohol (and dispenser),
    different types of solder, sponge, solder paste, heat shrink, etc. A good
    clean workbench with magnifying light as well should go without saying.
    These things aren't that expensive, so don't cheap out, get them all and
    good quality stuff.

    3) If you have stranded wire twist the wires together at the end before
    you do anything. Always wet the tip of the soldering iron with solder and
    make sure its nice and shiny and clean. If neccessary put some flux on
    the wire (probably isn't neccesary in this case). Wet the ends you wish
    to join with solder. (You can put them in a vise indepently to hold them
    while you wet them). Then simply insert the wire in the pin as best you
    can and heat it up with the iron which will reflow the solder as
    appropriate. Seal with heatshrink if you feel its neccessary. Good
    soldering skills take practice but it also takes decent equipment.
    The best way is to stop screwing around with nasty ass chemicals which are
    incredibly toxic and will give you crappy results. You think any company
    would seriously do this stuff? Even for prototyping? For prototyping if
    it has to be done in house its usually done with a milling machine.
    Otherwise, you could just design PCBs on some CAD software (Eagle for
    instance) and then send them out to a board house. They don't charge that
    much. Why would you want to expose yourself to those chemicals if you
    don't have to? What do you plan to do with them once you've used them?
    Please don't tell me you are going to dump them down the drain.
    You feel guilty about taking a part from work that costs a couple cents,
    but not playing with nasty chemicals which you have no good way to dispose
    of? Sheesh, I take pens from work which cost more than diodes inadvertantly
    all the time. I can't imagine they'll miss it. However, it depends where
    in the "DC area" you are. Mark Electronics and Electronics Plus (both in
    Beltsville) are reasonably decent. There are plenty of distributors
    (Allied, Active, Newark, etc) in this area, although they may not want to
    deal with a hobbyist.
  15. Dan Lenski

    Dan Lenski Guest

    Point taken :) I *do* work in a lab and know something about handling
    hazardous chemicals, however I agree that I'd best avoid working with them
    at home!!
    Wow!!!! I *live* in Beltsville for 1.5 years now. I'd never heard of
    either of those places. Will check 'em out ASAP. Thanks for the tips.

  16. Dan Lenski

    Dan Lenski Guest

    Thanks for all the advice, everyone!

    I had been hesitant to try Veroboard because it seems expensive and I know
    I'll make lots of mistakes. Today I practiced point-to-point soldering
    and was awful at it, so I think I need to use some method that will
    require me to not solder little wires to little leads! Today I found this
    site with some amazingly cheap Veroboard-type stuff: : Veroboard $1.65 : DIP prototyping board $0.95

    Thought I'd pass those links along... about 5x cheaper than anything I'd
    seen before!! They also sell kits of capacitors, resistors, ICs, etc.
    that seem quite well priced.

    Dan Lenski
  17. Guest

    Thanks for the tips, Bob. I think my problem may have been that I was
    using a plastic perfboard with no copper cladding. Whenever a drop of
    solder touched the perfboard, it would cling to the nearby metal. This
    made a mess when trying to solder wires close to the surface of the

    Is it correct that solder will NOT adhere to a plastic surface?

    I had a much easier time soldering two wires which weren't right next
    to the metal surface. I guess the board with copper pads is easier to
    work with because the solder will adhere to it.

    Dan Lenski
  18. Bob Myers

    Bob Myers Guest

    No, stick with it - sooner or later, you're going to pretty
    much HAVE to be able to "solder little wires to little leads,"
    so you might as well practice it now. You'll catch on. A
    couple of tips:

    1. Don't make the common mistake of pulling the iron away
    the moment the solder starts to flow; you WANT to get the
    melted solder good and hot, so that it flows properly around
    (and into, for stranded wire) the conductors. With the
    exception of some semiconductor devices, you don't need
    to worry about overheating the components - and for those
    that do have this concern, you just need to put a heatsink of
    some sort (they're sold in clip-on form, or you can simply place
    you needle-nose pliers between the joint to be soldered and
    the body of the component, if you're blessed with three hands...:)

    2. Make sure the pieces to be soldered are clean - surface
    oxidation (or worse yet, some insulating material left on a
    wire) with really interfere with the soldering process.

    3. Don't use so much solder that you wind up with a huge
    glob, but don't skimp, either - a little practice will teach you
    the proper amount.

    Remember, a good solder joint will be clean and shiny, and
    the solder will have flowed well onto the entire surface of the
    conductors to be joined - it should be well-adhered to these
    surfaces, and not look like it's just barely sitting on top of the
    surface ready to be picked off. You should expect to see
    some smoke from the joint during the soldering process - that's
    also no problem, and is not a sign that you're overheating
    anything; it's just flux and other impurities burning off.

    Bob M.
  19. Bob Myers

    Bob Myers Guest

    In general, that's correct - it will, of couse, melt many plastics
    while hot, and can really make a mess of things.

    Not all metals are solderable, either; copper conductors
    obviously are, including wiring which has been "tinned"
    (coated with a thin covering of solder or some other
    metal/alloy, which both improves the solderability as well
    as protecting the bare copper surface from oxidation).
    Aluminum, on the other hand, is not easily solderable
    with standard tin/lead solders - you can get it hot
    enough, of course, but regular solder will just bead
    up on an aluminum surface and refuse to "stick."

    Yes, that's pretty typical - beside the solder adhering to
    the "wrong" surface, having your wires in contact with
    metal for no good reason just makes for that much more
    metal you need to heat up - and some smaller irons might
    not be up to the task, thus making "cold" solder joints
    a lot more likely.

    Bob M.
  20. quietguy

    quietguy Guest

    As a suggestion Dan try and pick up an old electronic device or two or three at
    the tip - radios, cassette player, video player etc - their boards have lots
    of bits on then that you can practice unsoldering and resoldering, and
    soldering wires etc etc, and it will not matter if you ruin them (which you
    probably will until you get real good at soldering)

    But don't use old monitors or TV sets - these are best left for much later

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