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then determine the delay between triggers so that everyone
has a chance to see your character in action. The downside
to this method is that if there is a break in your visitors,
your prop is still going to activate.
If you are fortunate enough to have someone available
to monitor your prop, you will probably want to use a
pushbutton trigger. This method is virtually foolproof and
gives you the ability to choose the optimum trigger point.
Oftentimes, you don’t want the first person to trigger your
routine but would like to delay its activation until your
intended victim arrives. Building a wired pushbutton is a
simple do-it-yourself project. If you’re interested, check out
the one at http://tinyurl.com/ooupa6z.
There are also plenty of wireless models available that
activate a relay which can be connected to your character
and used to activate it (Figure 1). The most precise choice
is often to have a person on hand that activates your
character at exactly the right moment. However, we often
do not have this luxury. In those cases, we need to find
another solution that will accomplish the task.
A step mat is easy to use, reliable, and can provide a
very accurate trigger point. These work the best in
darkened hallways where you can control the path your
guests will take. The biggest drawback of these triggers is
that they can easily be avoided. Properly disguising them is
a must! Installing the mat under carpet if indoors works
well. Do not just lay it out on the sidewalk and expect it to
be effective. If you use it outside on a trail, try burying it
under a thin layer of leaves. You may even want to further
camouflage it by painting it and gluing a few leaves to the
top to help hide it if the covering leaves are displaced.
Making your own step mat is an easy process that
requires only some cardboard, aluminum foil, and wire,
along with a little time. Check out the example at
http://tinyurl.com/nat36ke or purchase one like this from
Monster Guts (see Resources).
IR Light Barrier
A break beam such as the Velleman MK120 can be
another good choice when you are able to channel your
guests down a specific passageway (Figure 2). It uses an IR
emitter to send a beam which is bounced off of a receiver
on the other side of the walkway. This gives you very
precise prop activation, but does require the placement of
two components that need to stay aligned to work. Select
a mounting location where you can conceal both pieces at
the proper height. You also want to be sure they are
securely mounted so they cannot be bumped into and
moved out of alignment. A very useful modification to this
kit can be found at http://tinyurl.com/yea9le4.
Passive Infrared Sensor
Passive Infrared (PIR) sensors work by detecting
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