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Newbie/Outsider question: what are resistors actually made of?

Discussion in 'Electronic Basics' started by JennaMyria, Jun 26, 2005.

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  1. JennaMyria

    JennaMyria Guest

    Hello everybody!
    My name is Myria and I really don't belong into this group at all, but
    I do have a question and searching the web doesn't really get me
    anywhere, because I guess I lack some basic understanding of
    electronics. I was hoping you could help me.
    Simple question: What are resistors actually made of? I mean the inside
    material. I know it must be some kind of substance that leads
    electricity more slowly (hope I phrase that right), but I am interested
    in the actual inside materials.
    Reason: My husbands grandfather was a radio/TV repair guy from the 50s
    to the late 80s and we inherited a huge collection of, well, different
    kinds of resistors (and a couple of capacitators). We couldn't sell
    them and I was wondering if I could use them in my craft projects. As I
    am working with children, I need to know if there is anything inside
    those resistors that is inherently dangerous/poisonous like mercury or
    maybe lead. And could it be dangerous by contact alone, or if they
    swallowed a resistor? (They are not that age group, but the weirdest
    things do happen. In todays suing happy society, you cannot be careful
    Any info is appreciated. Thanks.
  2. Randy Day

    Randy Day Guest

    The older resistors were mostly carbon in a ceramic(?) shell.
    The hard shell caps were usually ceramic, too. You may find
    a few waxy caps, but I can't recall their composition.
    The electrolytic type caps may have some chemicals in them,
    but they usually used metal cans as containers.

    If the leads have solder on them, the solder likely contains
    trace amounts of lead. Not enough to be a concern, I would
    think; you would probably have to be more worried about
    stomach punctures if one got swallowed.

    I've been around components like that for almost as long
    as grandpa, and it ain't hurt me none! <blink, blink, twitch, twitch>

  3. One day JennaMyria got dressed and committed to text
    Also remember that such components are cheap as pollies promises these days
    If you want to get the kids into electronics spend the money on training,
    the components are secondary, also the old ones might also be suspect.
  4. JeffM

    JeffM Guest

    we inherited a huge collection of...resistors
    Carbon composition resistors are a carbon slug inside molded phenolic.
    Modern film resistors are ceramic INSIDE.
    Wirewound resistors (old and new) use ceramics, inside and out.
    Very old ones will have paper cases with beeswax.
    Yup. Avoid anything that looks like a canister.
  5. JennaMyria

    JennaMyria Guest

    Thank you all so far! I am however still uncertain.
    I do not intend to get the kids into electronis, but I really intend
    the stuff to be used in crafts, i.e. glue them to cardboard or make
    jewelery out of the stuff!!!
    And I am afraid that I don't really know what "phenolic Bakelite" is,
    although I will go and google it immediately. I really just want to
    know if it is safe to have kids touching those little resistors or
    having them wear a piece on a string around their neck.
    Thanks, My
  6. Chris

    Chris Guest

    Hi, Myria. The wires coming out of the resistors almost certainly have
    solder coating on them, which is partly lead. If the children are
    still small enough to put their hands in their mouths (about 10 to 12
    years old, from my experience), they can ingest the lead with possible
    long-term health effects. If they're older, please tell them washup is
    required immediately after this "craft" stuff.

    The other components may have other toxic elements in them, depending
    on what you have. Be especially careful with any high voltage sealed
    capacitors made more than 25 years ago. These usually look like small
    oblong sealed metal cans with two prongs coming out the top. If you
    have any of these, you should handle them only with disposable rubber
    gloves. Place them in a thick plastic garbage bag, and put the garbage
    bag in a box for carrying. Strip off the disposable gloves and put
    them in the bag, too. PCBs are absorbed through the skin, and are very

    Actually, it's probably better to just box the whole works up and drop
    it off at a local trade school or junior/technical college that has an
    electronics program. As long as you're not looking for a receipt for
    tax purposes, and you don't give them any '60s or '70s vintage high
    voltage caps, they'll be happy to sort out what they need and chuck the
    rest. If you have any of those old HV caps, show them the separate
    garbage bag/box combination mentioned above and ask them for advice as
    to proper disposal. These may contain PCBs in their dielectric oil,
    which causes birth defects and cancer, especially in children.

    Good luck
  7. John Fields

    John Fields Guest

  8. Chris

    Chris Guest

    Somehow, I edited out the last paragraph.

    It's probably not a good idea to expose kids to old electronics
    components in a crafts environment. (Of course, if they're interested
    in electronics as a hobby, that's a different story). If you're
    thinking about introducing older (13+) kids to low temp tin/lead
    soldering (possibly metalcraft or jewelery making skills?) it would
    probably be better just to practice with 8 to 24 gauge solid copper
    tinned wire. You can strip the insulation off telephone wire or house
    wiring wire with a wire stripper, buy a small spool of rosin based
    60-40 solder and a soldering iron, and you're good to go. I really
    can't think of any other reason to do this that justifies dealing with
    lead or the other possible problems. Best just to raise a glass to the
    old tech, and then get rid of the stuff where it will do some good and
    maybe help somebody learn something. I'll bet that's what he'd want.

  9. JeffM

    JeffM Guest

    I don't really know what "phenolic Bakelite" is
    The same plastic that PC boards and knobs used to be made of.
    Fred Astaire liked dance floors made of the stuff.

    Unless the kids have massive oral fixations
    and continually suck on the tinned leads (wires with solder on them),
    as Fields says, it's no big deal.
    Have them wash their hand before you send them home.
    (Guessing you already do this.)

    Foley specifically mentioned polychlorinated biphenyls (PCBs).
    Yup. I already said that canisters are to be avoided.
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