heat shrink tubing question

Discussion in 'The Projects Forum' started by coeng, Nov 3, 2009.

  1. coeng

    Thread Starter Member

    Oct 29, 2009
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    0
    Is it not a good idea to cover a resistor with heat shrink tubing?

    For my garage door monitor circuit I have a 12V transformer plugged into the wall (unregulated, its actually 15.6V). I soldered the positive lead into a 1K resistor. The other end of the resistor runs (via 18 gauge bell wire) across my basement and into the garage connecting to two reed switches (in parallel) which then runs back into basement to two my two 5mm LEDs (in series) which then returns back to my transformer. I figure about 11 mA .... (15.6V-2.5V-2.5V) / 1000 ~ 11ma ..... runs through my circuit.
    I covered the 1K resistor entirely in shrink tubing so that I would not have any exposed contacts. I also covered the leads of the LEDs entirely with shrink tubing as well. Is this OK?
     
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    That is perfectly fine...... better than leaving exposed wires/connections to short out on something....


    My .02
     
  3. coeng

    Thread Starter Member

    Oct 29, 2009
    32
    0
    Also, is there a low-cost alternative to using the heat from my soldering gun to do a crappy job shrinking the tubing? I don't know much about heat guns but would buy one if it did a clean job and was relatively low cost.
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    I use a lighter (cigarette lighter) just dont hold the flame on there too long, and do small quick passes until the shrink tubing is shrunk to the size you need......



    My. 02
     
  5. coeng

    Thread Starter Member

    Oct 29, 2009
    32
    0

    Thanks. That certainly is low-cost. I would still like to know about mini heat guns if anyone uses one.
     
  6. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    I use this one in particular since it is the lowest cost one I could find http://www.techtoolsupply.com/ProductDetails.asp?ProductCode=1873, I also use the heat gun to remove surface mount/thru hole components off of PCB's when salvaging components......


    My .02
     
  7. Papabravo

    Expert

    Feb 24, 2006
    10,140
    1,790
    A 1500W hair dryer might also do the job. Try the one your wife, mistress, or GF uses before making a purchase.
     
  8. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
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    I think heat guns are cheap. You do not need top quality. I have used a cheap one for almost 10 years now, but most for heat shrink tubing etc. If your girl(s) have an industrial strength hairdryer so might also that work. I do not like to use a solder iron. Because it tends to overheat the tube so it get to stiff
     
  9. coeng

    Thread Starter Member

    Oct 29, 2009
    32
    0

    Perfect. Just added to my Christmas wish list. Thanks.
     
  10. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
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    I see only two possible objections to the heat shrink tubing. First, it might be inconvenient if it is not transparent, as you've covered up the color code. Makes for a little extra work should the resistor need to be replaced (i.e., you have to strip off the heat shrink to see the color code). Second, if the resistor is running near its rated power, you've changed the heat exchange characteristics with the surrounding air; this might result in a lowered life of the component. But if the resistor doesn't get very warm during operation, it's not an issue.
     
  11. SgtWookie

    Expert

    Jul 17, 2007
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  12. spacewrench

    Member

    Oct 5, 2009
    58
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    I also have a Harbor Freight Special, but it's not as swoopy and designer-y as SgtWookie's above. On the other hand, I got it for $9.99 on sale. It works better than any hair dryer I've ever used -- I think hair dryers move too much air, so they don't get quite hot enough, even if the wattage is there.
     
  13. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    I use a combination butane torch / soldering iron. You have to be careful of scorch, but it works well too. Just used about 4 feet of the stuff myself for something none electronics related.
     
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