only requires one pin for interfacing. The board is so easy
to use that a manual isn’t even required. All the necessary
information is printed on the back of the board (see
Figure 2). We’ll get into the details when we begin our
experiments this month, but there’s one thing I want to
mention at this point.
Because the board provides an analog output,
interfacing it with a PICAXE processor is almost identical to
the MCP9700A based temperature measurement project
we covered back in the December 2012 issue of Nuts &
Volts. As a result, if you have no interest or need to
monitor any temperatures higher than 257°F, you can
easily substitute an MCP9700A sensor for the AD8495
board and thermocouple sensor in any of this month’s
experiments. The only software change would be to edit
the portion of the software that converts raw ADC (
analog-to-digital converter) input to degrees Fahrenheit, so that it
matches the one we used in the original MCP9700A
project. Also, the techniques we’ll be using to record and
display data can be readily applied to just about any data
logging project you may want to implement.
The AD8495 printed circuit board (PCB) can be used
with any K-type thermocouple sensor. This type of sensor
is readily available on the Internet, but I chose one from
Auber Instruments (see Figure 3 and Table 1) because its
physical dimensions suited my requirements and it can
measure up to 900°F, which is sufficient for my
application. The Auber thermocouple comes with two
standard spade connectors that can easily be removed, so
the probe can be directly connected to the Adafruit
thermocouple amplifier board.
However, when I ordered the probe, I also ordered a
pair of thermocouple connectors — one of which is a
female panel-mount connector (see Figure 4 and Table 1)
because I plan to eventually mount the electronics inside
a plastic project box. Also, the male connector fits into the
standard female connector on one of my multimeters, so I
can use the probe that way as well.
Experiment 1: Using a Thermocouple
to Measure Temperature
In this experiment, we’re simply going to test the
thermocouple interface to make sure it’s functioning
correctly. The schematic for the experiment is presented in
SHARPENING YOUR TOOLS OF CREATIVITY
February 2016 15
■ FIGURE 3. Thermocouple probe.
■ FIGURE 2. AD8495 thermocouple amplifier board (back).
■ FIGURE 4. Thermocouple connector pair.
Table 1. Product Source
I2C Non-Volatile FRAM
Breakout Board — 256 kBit
( 32 kByte)
Amplifier Breakout Board
K- Type Thermocouple Probe
for Smoker or Oven
Male and Female Connectors auberins.com