deletions | additions       diff --git a/Circuits.tex b/Circuits.tex  index 5b37434..4555d30 100644  --- a/Circuits.tex  +++ b/Circuits.tex 
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\subsubsection{The Sensor Array}  The sensor array has two functions: to detect how many candlelights are present and to test whether the candlelights that are present are flickering. Each candlelight is tested in a separate well with dedicated sensors for only that well. In other words, there is a separate collection of sensors for each candlelight.  Light from the candlelight is detected with a PBW34 yellow photodiode.\cite{VishaySemiconductors:2011} If a candlelight is present, and on, the light absorbed by the photodiode is converted to a current which in turn biases a TIP142 transistor\cite{ONSemiconductor:2012},\cite{SharpMicroelectronics:2009}. transistor \cite{ONSemiconductor:2012}, \cite{SharpMicroelectronics:2009}.  The output from each transistor is combined in a CD4067 digital/analog 16-to-1 multiplexer, so that the PIC can select one signal at a time\cite{TexasInstruments:2003}. Only 9 channels are used. The output from the mux is passed through a LM358 Op-Amp to amplify the signal\cite{FairchildSemiconductor:2010}. signal \cite{FairchildSemiconductor:2010}.  Presence is detected with the aid of superbright LEDs mounted beneath the candlelight wells, under the tray. There is one LED for each well. The LEDs are powered by 5V at 2A.   When there is no candlelight present, the LED shines into the photodiode and the PIC is programmed to recognize the constant intensity detected. 
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\subsubsection{Servo Motors Driver Circuit}  Driving servo motors is a simple operation. The 3 servos are operated at the same time, and in the same direction, so the voltage supplies, the grounds and the signals from the PIC are lumped together. The servos are powered with 5V at high current, #A, which is their maximum draw for maximum mechanical power. The signal wire for the 3 servos is connected to the signal hub to receive PWM from the PIC. A ground reference from the PIC is connected to the ground for the servos\cite{Electronics-Blog.comblog:2008}. servos \cite{Electronics-Blog.comblog:2008}.  The servo driver circuit can be seen in figure #. (!!!!!!!) \subsubsection{Stepper Motors Driver Circuit}  Each of the two stepper motors has a ULC2003A IC transistor array to amplify the sequence signal from the PIC and provide the stepper coils with current\cite{TexasInstruments:2013}. current \cite{TexasInstruments:2013}.  The input for the two ICs is joined because like the servo motors, both steppers operate at the same time, in the same direction, and therefore receive the same signal from the PIC simultaneously. The four inputs connect to the signal hub for communication with the PIC. A ground reference for the PIC is connected to the stepper driver board. The stepper driver board is powered by 5V at 2A. The four outputs from each IC connect to one unipolar stepper motor. Each unipolar stepper motor has two power leads connected to the same 5V that powers the driver board\cite{GETechwiki:2008}. board \cite{GETechwiki:2008}.  The stepper driver circuit can be seen in figure #. (!!!!!!) \subsubsection{Signal Hub} 
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\subsubsection{Power Supply Network}  The device is powered by a MIOS 480W ATX computer power supply, which provides the PIC with 12V at 1A, the servo motors with 5V at 22A (!), and 5V at 2A which powers everything else, including the IR sensor board, the yellow sensor board, the stepper motor driver board, and the steppers themselves\cite{LazarRozenblat:2013}. themselves \cite{LazarRozenblat:2013}.  A separate power and ground wire is run to each subsystem, and the wires converge immediately before the power supply. The wires from the power supply carrying 5V at 2 and 22A respectively first pass through the emergency cut-off switch, allowing for the immediate halt of current flow to all components of the device except for the PIC and illumination LEDs. These components do not move, and are powered by extremely low current, therefore these remaining live wire does not pose a risk. A full outline of the circuitry of the device can be seen in figure #. (!!!!!) \subsection{Supporting Calculations}  \subsection{Suggestions for Improvement}