Adding simple sensors and output devices creates a circuit
that can accomplish a wide range of functions. This article
describes a good example of how to assemble an Arduino
Nano in a fairly simple project.
For some time, I had been interested in purchasing a
3D printer. My original reluctance was the fact that I had
lots of interest but little need for
one. When my grandson expressed
a desire in having one as well, it was
all I needed as an excuse for
purchasing one of the higher-end
We chose an Ultimaker 2+, and
have been quite pleased with it.
That is not to say it didn’t have a
challenge or two. Printing with PLS
plastic was a breeze, however,
switching to ABS plastic presented
ABS plastic is more durable, but
prints at a much higher
temperature. My first large print in
ABS showed lots of layer separation.
A quick Google search of the
problem revealed the need for an
enclosure for the 3D printer that
would keep the ambient temperature higher.
Plans for a fully enclosed plywood box were
made and it became evident that some type of
temperature control would be a necessary feature. The
heat comes from the printer itself, but a full enclosure
might very well produce too high an ambient
temperature. A number of posts I found on the Internet
talked about a fan for cooling and taking away fumes
from the ABS. The fan would need temperature control,
at which point an Arduino Nano controlled fan came to
A little planning produced the circuit shown in
Figure 1. The main components are: the Nano; a
BMP/BME280 temperature, humidity, and pressure
sensor on a very small breakout board; an LCD display; a
Darlington power transistor to turn the fan on and off;
the fan itself; and a couple of pushbutton switches to
change the temperature settings.
The BMP/BME280 board is something I have been
using in conjunction with the digital clocks I build.
Adafruit and SparkFun carry these, and other models are
available on eBay. Any of these should work, as long as
it can communicate using the I2C protocol.
The 20-character by four-line LCD display is another
component I have had experience with. This LCD has the
small added board that allows I2C communication. Since
both boards utilize the I2C interface to pins A4 and A5 on
the Arduino Nano, connections to these devices are very
Every I2C device has its own address; this one byte
SERVO 03.2018 31
Figure 2. The box enclosure with LCD display and pushbuttons.
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Figure 3. Point-to-point wiring inside the enclosure.