diff --git a/docs/hardware/.gitignore b/docs/hardware/.gitignore
new file mode 100644
index 0000000..8491230
--- /dev/null
+++ b/docs/hardware/.gitignore
@@ -0,0 +1,3 @@
+circuits.aux
+circuits.log
+circuits.pdf
diff --git a/docs/hardware/build_circuits.sh b/docs/hardware/build_circuits.sh
new file mode 100755
index 0000000..f82d0ac
--- /dev/null
+++ b/docs/hardware/build_circuits.sh
@@ -0,0 +1 @@
+xelatex circuits.tex
diff --git a/docs/hardware/circuits.tex b/docs/hardware/circuits.tex
new file mode 100644
index 0000000..79f033c
--- /dev/null
+++ b/docs/hardware/circuits.tex
@@ -0,0 +1,109 @@
+\documentclass[a4paper]{scrartcl}
+
+\usepackage{tikz}
+\usepackage[european resistor]{circuitikz}
+\usepackage{siunitx}
+
+\begin{document}
+
+\begin{figure}
+  \begin{circuitikz}
+    % Raspberry Pi
+    \draw (0.5, -0.5) rectangle (3, 3.5);
+    \node at (1.5, 3) {\textbf{RPi}};
+
+    \draw (3.5, 2) to [short] (2.5, 2) node [left] {GND};
+    \draw (3.5, 0) to [short] (2.5, 0) node [left] {GPIO18};
+
+    % Bread Board 1
+    \draw (4, -0.5) rectangle (7.5, 3.5);
+    \node at (5, 3) {\textbf{BB1}};
+
+    \draw (3.5, 2) to [short] (4.5, 2) node [circ] {}
+      to [short] (5.5, 2) node [circ] {}
+      to [short] (8, 2);
+
+    \draw (3.5, 0) to [short] (4.5, 0) node [circ] {}
+      to [short] (5.5, 0) node [circ] {}
+      to [R, l=$R_2$] (7.5, 0)
+      to [short] (8, 0);
+
+    \draw (4.5, 2) to [push button] (4.5, 0);
+    \draw (5.5, 2) to [R, l=$R_1$] (5.5, 0);
+
+    % Bread Board 2
+    \draw (8.5, -3.5) rectangle (11.5, 3.5);
+    \node at (10, 3) {\textbf{BB2}};
+
+    \draw (8, 2) to [short] (9, 2) node [circ] {}
+      to [short] (12, 2);
+
+    \draw (9, 1) node [circ] {} to [empty led] (11, 1) node [circ] {}
+      to [short] (12, 1);
+
+    \draw (8, 0) to [short] (9.5, 0)
+      to [empty led] (11.5, 0)
+      to [short] (12, 0);
+
+    \draw (9, -1) node [circ] {} to [R, l=$R_3$] (11, -1)
+      to [short] (12, -1);
+
+    \draw (10, -2) to [short] (12, -2);
+    \draw (11, -3) to [short] (12, -3);
+
+    \draw (9, 4) to [short] (9, -1)
+      to [R, l=$R_4$] (9, -3)
+      to [short] (9, -4);
+
+    \draw (10, -2) to [short] (10, -4);
+
+    \draw (11, 4) to [short] (11, 1);
+    \draw (11, -3) to [short] (11, -4);
+
+    % Door
+    \draw (8.5, 4.5) rectangle (11.5, 6.5);
+    \node at (9.5, 6) {\textbf{Door}};
+
+    \draw (9, 5) to [empty led] (11, 5);
+
+    \draw (9, 5) to [short] (9, 4);
+
+    \draw (11, 5) to [short] (11, 4);
+
+    % ADMN
+    \draw (12.5, -3.5) rectangle (15, 3.5);
+    \node at (13.5, 3) {\textbf{Arduino}};
+
+    \draw (12, 2) to [short] (13, 2) node [right] {GND};
+    \draw (12, 1) to [short] (13, 1) node [right] {D12};
+    \draw (12, 0) to [short] (13, 0) node [right] {D10};
+    \draw (12, -1) to [short] (13, -1) node [right] {A0};
+    \draw (12, -2) to [short] (13, -2) node [right] {\SI{5}{\volt}};
+    \draw (12, -3) to [short] (13, -3) node [right] {D13};
+
+    % Sensor
+    \draw (8.5, -4.5) rectangle (11.5, -7);
+    \node at (9.5, -6.5) {\textbf{Sensor}};
+
+
+    \draw (9, -4) to [short] (9, -5) node [rotate=90, left] {black};
+    \draw (10, -4) to [short] (10, -5) node [rotate=90, left] {blue};
+    \draw (11, -4) to [short] (11, -5) node [rotate=90, left] {red};
+
+  \end{circuitikz}
+  \caption{
+    $R_1 = \SI{33}{\kilo\ohm} \pm \SI{2}{\percent}$,
+    $R_2 = \SI{28}{\kilo\ohm} \pm \SI{2}{\percent}$,
+    $R_3 = \SI{68}{\kilo\ohm} \pm \SI{1}{\percent}$,
+    $R_4 = \SI{200}{\ohm} \pm \SI{1}{\percent}$,
+  }
+\end{figure}
+
+
+\end{document}
+
+%%% Local Variables:
+%%% coding: utf-8
+%%% mode: latex
+%%% TeX-engine: xetex
+%%% End: