Adafruit. I use these boards because it’s easy to copy the
circuit from the breadboard. I added right-angle headers for
plugging in the display, servo, and programmer. The case
has bosses for mounting the board above the display when
viewed from the back.
When testing the circuit on a breadboard, I discovered
that large movements of my bigger servos would reset the
system due to a voltage drop caused by the current drain
from the large servo. I solved this by adding a 470 µF
capacitor across the power lines on the circuit board to
provide a buffer for the power surges.
Hopefully, if you’ve paid attention to articles in this
magazine, you know that in a live application — such as a
combat robot — you should always separate the logic
power supply from the motor or servo power supply.
Referring to Figure 5, the tester has several inputs.
When the tester powers up, the servo output defaults to
1,500 microseconds (µS), so any attached device should be
in the middle position. The small blue buttons can be used
to test the “ideal” cases of left, center, and right, with
signals of 1,000 µS, 1,500 µS, and 2,000 µS, respectively.
The slider across the bottom can be used to test the
extremes of your device. This can be used to set the
control signal anywhere from 0 to 2,500 microseconds.
The number immediately above the slider shows the
current slider value, which isn’t actually transmitted to the
processor until you lift your finger or the stylus.
The large blue number always shows the value — in
microseconds — of the actual control signal currently being
sent. The red and green buttons can be used to fine-tune
the signal in steps of 1 or 10
microseconds, up or down. This
allows you to position the servo or
actuator precisely where you want it.
You need to take some care as
you explore the full range of the
device you are testing. Some servos
made unhappy “chattering” noises
when I tried to move past their
endpoints. A few locked up at the
extreme end of the motion and
would not return until powered off
and then on again.
Once you’ve found the desired
position of your device, you can read
the blue number from the display
and enter that into your servo control
In the few months that I’ve been
using it, my Deluxe Servo Tester has
become one of the tools that makes
me wonder how I ever got along
without it, and why did I wait so
long to make it.
I hope you find it as useful as I do. SV
Personal CNC Mills
PCNC 1100 Series 3
Shown here with
Shown below is an articulated humanoid
robot leg, built by researchers at the
Drexel Autonomous System Lab (DASL)
with a Tormach PCNC 1100 milling
machine. DASL researcher Roy Gross
estimates that somewhere between 300
and 400 components for “HUBO+” has
been machined on their PCNC 1100.
Phone: 360-515-0691 ; email@example.com
; 35A Continuous -
; 6.5V - 40V
; Built in Voltage Reg can power the Arduino
; Current sensor outputs can be sent to any analog pin
; Over temp and over current protection
Our Highest Current motor control for Arduino;
MEGAMOTO GT Shield
; 120A+ H-Bridge -
; 8V - 42V
; Overload protected
; RC and Analog Pot input
; Supports 8 AWG wires!
; 2.85” x 2. 25” x 1.75”
; 7V - 28V
; Triple 6.5A / 8.0A Peak H-Bridges
; Current/Temp limiting
; R/C inputs w/mixing
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; 2.0" x 2.1" x . 5"
SERVO 12.2015 35