The internal circuitry is very robust and includes
some nice features, including protection from
reverse polarity as well as from over-current and
Firgelli Technologies offers a wide range of
devices that the DIY animatronics builder will find
useful (see Resources). The product that really
caught my eye was the miniature linear servos that
they stock (Figure 6). Their small size and
substantial torque make them the ideal solution for
so many applications. Check out how they are
being integrated into the open source Ada robotic
hand at http://tinyurl.com/z7qt65q. It’s a
fantastic job and a very worthwhile cause!
How often have you been considering a
purchase and spent more time figuring out the
necessary hardware than you did in choosing the
original product? Well, no worries about that
problem when purchasing these miniature linear
servos as they include all the required mounting
hardware. Now, that’s great customer service!
These are equipped with square shafts which
mean they are non-rotating. This can be a distinct
advantage, but does require a little creativity when
it comes to mounting (see Figure 7).
These miniature linear servos are surprisingly
robust considering their small size. I am coming up
with more and more places to include them as I
get comfortable with their use. They are sure to
show up in many of my builds — especially those
that require strength but need to fit in tight
I wanted to put them to the test, so I installed
one on an aluminum pop-up mechanism (Figure
8). My plan was to install a lightweight plastic skull
on it, then have it move up and down from behind
a wall. I felt this would be a challenge for the tiny
device, but it handled it with ease.
Always wanting to push the envelope, I put a
heavier hairdresser’s head on it and it did not mind
a bit. These things are impressive!
High Speed Linear Actuator
The availability of the high speed linear actuator
may be the ultimate electric solution! The
performance of these can compete in many ways
with pneumatic systems without all the extra
required equipment (see Figure 9 and Figure 10.)
The model I am using came from Fright Props and is
controlled by their PicoBoo controller (see
Since many of the designs we devise require
quick movements and the moving of heavier loads,
we naturally think that pneumatics is the only
solution. High speed linear actuators do an
SERVO 07.2016 57
Figure 9. Look Ma, no air!
Figure 8. We have liftoff! Figure 7. Moving on a hinge.
Figure 10. The brains of the