Your robotic problems solved here.
SERVO 01.2014 17
No doubt there are other good
chargers out there for your money,
but you asked me and I have tried
quite a few and settled on these
two as worth their money.
If you can spring for the Hitec
X4, you’ll be content for life with its
ability to charge four completely
different batteries at the same time.
This is very handy at a robot
competition! Regardless, the two
front-runners (in my opinion) will
make you very happy!
Q. I’m working on a 3D printer kit and noticed it uses an inexpensive thermistor sensor
to track the temperature of the head.
Would a solid-state temperature
sensor provide a smoother control? If
so, which sensor would you
A. The answer to your first question is no. A solid-state solution will not give you what
you want. The reason that I say this is
that these “single chip” solutions that
you talk to with I2C or SPI are not as
accurate as a thermistor that is affixed
directly to the surface that you are
going to measure.
A thermistor will be
far more accurate if your
control system is using the
correct transfer equations
parameters to calculate
the temperature. The
thermistor will also
typically have a much
lower thermal mass and
will track temperatures
more quickly than a solid-state solution will.
I have used both
solutions, but for different
applications. I use a
thermistor with precision
amplifier components and
to calculate the precise
temperature of water in a sensor. I
use a solid-state I2C temperature
monitor soldered to a controller board
to tell me the approximate
temperature of my printed circuit
board (PCB) in its enclosure.
The former needs tight precision
(like your 3D printer head application);
the latter just needs reasonable
accuracy to let me know when my
system is beginning to overheat.
You’ll want to use the thermistor.
Make sure that it is solidly attached
to the print-head surface with some
Now for something completely
Recently, I came across a couple
of additions to the Digilent chipKIT
line that readers might be interested
in. The first addition is the chipKIT
CMOD (Figure 1). This small board
has a PIC32MX150F128D 32-bit
microcontroller on it running at
40 MHz. This is only half the speed of
Digilent’s usual chipKIT controller
boards. I’m not sure why they clocked
it down ... perhaps to reduce power?
This board is intended to go into
smaller projects since it’s only 2 cm x
7 cm. The physical size is the only
thing small about it though, if you are
used to using Arduino boards. The
CMOD has 128K of program space
and 32K of RAM, plus runs the
Arduino compatible MPIDE version of
the Arduino environment.
As my readers know, I’m very
fond of the chipKIT series boards