work at 3.3V direct drive, however, the
Activity board includes a protective
series resistor that modifies the signal
enough to render them inoperative.
Several methods to resolve the issue
were tried before deciding on a course
of action. We incorporated a driver
circuit that uses a pair of transistors and
two resistors that boost the pulses back
up to the 5V required by the linear
servos.
The design and construction of the
skeleton’s head was the responsibility of
Robert Risley. Robert has been
instrumental in contributing his creative
genius to many of the characters I have
built, and his insight and inspiration are
truly appreciated. He shares my belief
that we should always be pushing the
envelope in our creations and striving to work outside our
comfort zones. He once again hit it out of the park with
this design!
He started with a plastic Lindberg skull which has a
Monster Guts three-axis assembly mounted inside (see
Resources). This gives Robert an anatomically correct
starting point when sculpting the head. By adding Apoxie
Sculpt clay, he slowly builds up the features of the character
until he gets it absolutely perfect! Mission accomplished
(Figure 6)!
To increase the strength of the spine for mounting the
head, I modified it by inserting a threaded rod which runs
between the pelvis and the shoulders. This provides a solid
structure for attaching the skeleton to the façade, as well
as for securing the head to the body.
Before the skeleton can be chained to the wall, he must
first be stained the proper color. Robert made this happen
by liberally applying some Saddle Tan Gel Stain from Tandy
Leather and then wiping off the excess (see
Resources). This is our go-to stain whenever we are looking
to provide a weathered appearance to a prop or character
(Figure 7).
Parallax Activity Boards
Providing the illusion of life in our characters
requires more than a wee bit of hocus pocus! Once
the soundtrack was completed, it was time to wake up
the witches and get them moving. This massive
undertaking is the purview of our master puppeteer,
Brian Lincoln. His considerable skill is apparent when
you see how realistically the characters perform under
his direction.
For me, this is the most exciting part of the build.
Seeing the scenario I had imagined transcend to reality
is inspiring. It is also the time to discover if the project
will actually
operate in the
fashion you
intended.
Discovering
that you are
not as smart
as you
thought you were can be humbling, but the challenge lies
in adapting and overcoming the temporary setbacks you
encounter.
We decided to divide up the many functions of the two
characters between four individual Activity boards. This
would allow us to separate the body movements from the
head actions. It would also give us a tremendous amount
of flexibility in adding additional features in the future.
The Activity boards have the capability of controlling
eight separate mechanisms. The skeleton and witch’s heads
require four channels each, the skeleton body five, and the
witch’s body six. This left us with at least two unused
channels per board for other purposes (Figure 8).
DIY Animatronics
SERVO 10.2016 11
Figure 8. The brains of the operation are hidden inside.
Figure 6. The skeleton head comes
to life.
Figure 7. All painted up and
nowhere to go.
