NOx/O3 sensor
A NO2/O3 sensor using an Arduino Pro Mini and an Alphasense electrochemical sensor
The description is an excempt from the attached report. See the appendix in the report about creating the sensor for pictures and a more nicely formated text (this one here is flawed with the latex commands). The report is called "Christian_kandidatprojekt_Rettet3.pdf".
\paragraph{Step 1.} A protoboard is prepared and stribes are cut in the copper connections with a knife, a Dremel or other suitable tools, so that unwanted connections are avoided (See Figure \ref{fig:stepsdude}). Headers are soldered onto the holes in the Arduino Pro Mini, and these are soldered onto the proto board.
\paragraph{Step 2.} All connections to ground and the 5V DC power supply (VCC) are made using unicore jumper wires (red is power, black is ground). Two capacitors (100 nF and 10 nF) are connected between the power supply and ground, close to the gas sensors, to allow high frequency noise on the line to pass into ground and thus not disturb the sensors. A 10K pull-up resistor is placed between VCC and the signal from the DHT-22. Jumper wires are connected between the WE and AE signals of the sensors and the ADC.
\begin{figure}[ht]
\centering
\includegraphics[width=.8\linewidth]{graphics/apps/fritzing_A_type_sensor_node.png}
\caption[A visual representation of the components and connections of the A type sensor node]{A visual representation of the components and connections of the sensor node of A type. Made with open source software Fritzing (\url{www.fritzing.org})}
\label{fig:fritz1}
\end{figure}
\paragraph{Step 3.} The datalogger and the ADC are added to the protoboard. and connections are made between the SCL and SDA ports of the ADC and the A4 and A5 on the Arduino. A jumper wire is connected between the "address" pin on the ADC and ground\footnote{The address pin can be connected to four different positions so that up to four Adafruit ADCs can be connected at the same time.}.
\begin{figure}[h]
\centering
\includegraphics[width=.8\linewidth]{graphics/apps/IDC_connectors.png}
\caption[The connections of the IDC connector to the AFE]{The connections of the IDC connector to the AFE. Graphic is from \citet{AFE_manual}}
\label{fig:IDC}
\end{figure}
\paragraph{Step 4.} The insulation displacement connector (IDC) for the AFE is solderen onto the protoboard connecting the toxic gas sensors to the ADC. Consult Figure \ref{fig:IDC} and \ref{fig:IDC2}, for information about how the wires are placed in the IDC connector.