Experiment 12: Joining Two Wires Together
112 Chapter 3
After searching exhaustively I couldn’t find any laptop power cables shorter
than 3 feet, so I decided to shorten one myself. If you feel no need to do this,
you should try the following procedure on an old extension cord, just as an
exercise. You do need to go through these steps to acquire some practice in
soldering heavier, stranded wire and using heat-shrink tubing:- Use your wire cutters to chop the wire, and then a utility knife to split the
two conductors, with one shorter than the other. When splicing a pow-
er cord or similar cable containing two or more conductors, it’s good to
avoid having the joints opposite each other. They fit more snugly if they
are offset, and there’s less risk of a short circuit if a joint fails.
Figure 3-52 Figure 3-53 Figure 3-54
Figure 3-55 Figure 3-56 Figure 3-57
- Strip off a minimal amount of insulation. One-eighth of an inch (3 mm) is
sufficient. The automatic wire strippers that I mentioned in the shopping
list in Chapter 1 are especially convenient, but regular wire strippers will
do the job. - Cut two pieces of heat-shrink tubing, each 1 inch long, big enough to slide
over the separate conductors in your cable. Cut a separate 2-inch piece of
larger tubing that will slide over the entire joint when it’s done. The steps
described so far are illustrated in Figures 3-52 through 3-58. - Now for the most difficult part: activating your human memory. You have
to remember to slide the tubing onto the wire before you make your sol-
der joint, because the plugs on the ends of the wires will prevent you from
adding any heat-shrink tubing later. If you’re as impatient as I am, it’s very
difficult to remember to do this every time.
Figure 3-58. Figures 3-52 through 3-58
illustrate the sequence of steps to prepare
for making a shortened power cord for a
laptop computer power supply.