This Halloween, you can treat your tricksters to both dessert and a show. This project is easy to solder together and uses common tools
to assemble. Best of all, the animations for
the Halloween songs can be downloaded
for free!
Some of you clever readers are
probably thinking that this could be
repurposed for Christmas. You would be
right! In fact, I designed the electronics to be
reused for Halloween and Christmas by
swapping out the face front for each holiday.
It means less work to leave the decorations
up without the homeowner’s association
complaining that your decorations are out of
season. That means more time for Christmas
shopping, making cookies, or caroling, if
that’s what you’re in to.
There are two parts to this project: lights
and electronics. You get to use both your
creativity and your logic, so it’s a right
brain/left brain kind of deal.
Lights
The lights are the creative part of this
project. I made a pumpkin face, but you can
use your imagination to build whatever
scary face suits you: monster, ghost,
vampire, or politician.
The face has three animated parts: two
eyes and one mouth (unless your
imagination takes you in a different
direction). Each of these animated parts will
have six segments that are lit up with LED
strips. “Why does the mouth need six
segments if I only need open and closed?”
you might be asking. The answer has to do
with Preston Blair.
Animating a Mouth
Preston Blair was an animator who
worked on some of Walt Disney’s early
animated movies. He later worked at MGM
and Hanna-Barbera. Blair figured out that of
all the sounds an English speaker can make,
there are only 10 different mouth shapes
that are needed in order to produce them.
These mouth shapes mimic natural lip
movements and make the singing animation
look far more realistic.
When you’re doing a lighting animation,
however, you want to get as many of those
mouth shapes to appear correctly in the
least amount of lights. One approach is to
use a separate string of LED lights for each
mouth shape, but that’s inefficient. The
clever part of this project is that I figured
out how to get all 10 of Blair’s mouth
shapes with only six light segments. This is
done by adding or subtracting various
shapes in order to make the mouth look
natural (Figure 2). Neat, huh? (Yes, I
patented this approach. Feel free to use this
design for your own personal projects, but
you’ll need to contact me if you want to sell
a commercial product based on this.)
Planning for the
Animated Display
You could put all of the LED strips on
one layer of plywood, and I wouldn’t blame
you if you did. My approach is to do a little
more work to save a lot more time later. The
advantage of doing this is reuse of the
electronics and half of the construction. The
reuse approach will divide the animated
display into two major elements: the face
front, and the light box to hold the LED
strips that create the animation. The light
box will be reused, and the face front can
be swapped out (Figure 3).
It may be easier to understand this
approach if you view the face front and light
box from the side (Figure 4). The lights
extend past the height of the light box and
touch the diffuser directly.
I have a small yard, so the size of the
animated display I built is about 2’ x 3’. If
you have a bigger yard, you’re welcome to
scale up the size. The swappable face front
has two parts: a light diffuser and MDF
backing. The light diffuser is the same
acrylic panel that is typically installed in
September 2014 45
Smile
M / B / P
F / V
Consonant
E
A / I
L / Th
W / Q
U
O
FIGURE 2.
Mouthshapes.
FIGURE 3.
Finished
animated
display parts.