32 SERVO 01.2017
What are My Choices?
One possible source of power may be available directly
from your circuit. Many microprocessors can source very
small loads directly from their GPIO pins. However, most of
our applications will require more power than is available
using this option. This is where it is necessary to add an
additional external power source. Let’s look at some other
methods to get that extra power we need.
When a character is in close proximity to AC power and
will remain in a fixed location, then wall warts — also
known as AC adapters — become an easy and cost-effective
solution (Figure 1). These items come in regulated or
unregulated versions, with the regulated models being the
supplies of choice.
Be sure to always check the voltage output of your wall
warts with a digital multimeter before plugging them into
your valuable electronics. Just because it states on the label
that it is a certain voltage does not necessarily mean it is
true. I have seen unregulated wall warts measure out
significantly higher when unloaded than the stated voltage.
While some components may be more tolerant of higher
voltages, your sensitive electronics may have more stringent
requirements. This is one of those situations where a quick
check can save you a lot of time and frustration later. While
unregulated supplies are generally less expensive than the
regulated models, it is worth
the price to stick with the
There are also some
regulated power supplies that
come with multiple voltage
regulators at different voltages.
This allows a single wall wart
to satisfy the needs of your
components if they require
different voltages. I use this
setup for my Frankenstein
boards to supply the 5V and
12V it demands (Figure 2).
Many of our projects
require different voltages to
operate the various devices. Of
course, it is possible to regulate
the voltage with regulators.
The famous phrase, “Scotty, we need more power!” seems to pop into my head
whenever I am stretching the power envelope on a new creation. Since I don’t have
anyone named Scotty (or any other name, for that matter) to come to my aid when
called, it falls to me to consider and resolve this issue early in the planning stages.
Although this is not one of the most exciting parts of the prop building process, it is
crucial that these topics be addressed in order to be sure your characters have the
power they need to perform at their best.
Power to the Robots
Figure 1. Plenty of
wall wart choices.
By Steve Koci