Setting Fires With Electrical Timers

Tips for Constructing
Electrical Timers
Special care must be given to each electrical connection.
Be sure each one conducts electricity well and will not break
apart during transport. Soldering wires together makes a
much better connection than merely twisting them together.
To join two wires: strip insulation off the end of each wire,
twist them together and add a coating of solder. Wrap
electrical tape around the exposed wire and continue
wrapping down onto the insulated part of the wire for about
an inch (see Figures A and B). Make the tape tight against
the wire by pinching it and stretching it as you wrap. The
electrical tape prevents short circuits and protects the wires
from being pulled apart. (Helpful Tip: To get a tight fit
when wrapping tape around the thin wire in these recipes, we
recommend first cutting each piece of tape down the middle
to reduce its width by half.)
Here’s some advice on wire, batteries, battery snaps,
voltmeters, epoxy and shrink tubing:
• Wire: The gauge of a wire is the measure of its diameter.
Contrary to common sense, a lower number means it is a
thicker wire. For example, 18-gauge wire is thicker than
20-gauge wire. Don’t worry about using different gauge
wire on the same circuit. Thick wire is sold in many
places, thinner wire is harder to find. 18 and 20 gauge
wire can sometimes be found on the shelves of hardware
stores and auto part stores. For thinner wire, go to Radio
Shack. Beneath the colorful plastic insulation, wire is
either “solid-core” (a single wire) or “stranded” (multiple
smaller wires). Stranded wire is easier to work with
because it is more flexible and creates better soldered
connections. The solder seeps in between the strands of
wire. We strongly recommend using stranded wire.
• Batteries: Use batteries that say “alkaline.” Do not use
the misnamed “heavy duty” or “classic” batteries. Do not
use lithium cells. Do not use rechargeable nicad (nickelcadmium)
batteries. Only alkaline batteries release
sufficient amperage (current flow) to power a testingbulb
or an igniter. Weak batteries can cause false test
results. Testing with a light bulb or a Light Bulb Igniter
will drain batteries quickly. During testing, keep lots of
new batteries on hand and discard batteries that have less
than 8.8 volts. And, of course, use only brand new
batteries at the target.
• 9-Volt Battery Snaps: Clocks, toys, small radios and
anything else that uses a 9-volt battery will have a
battery-snap (sometimes called a battery cap or a battery
connector). It snaps onto the two terminals on the top of
the battery. Battery-snaps can be purchased at a hobby
shop or an electronic parts store such as Radio Shack. On
10
Figure A: Connecting Two Wires Together
Step one: Strip the ends of both wires
Step two: Hold the wires side by side and twist the
exposed ends around each other.
Step three: Add solder
Step four: Cut tape in half the long way to make
wrapping easier.
Step five: Wrap tape to completely cover the
exposed ends. Continue wrapping tape down onto the
insulated wire for an inch or so.