Team:Cornell/project/drylab/electronics

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<h1>Electronics - Water Level Sensing Circuit</h1>
<h1>Electronics - Water Level Sensing Circuit</h1>
<b>Why do we need it?</b><br>
<b>Why do we need it?</b><br>
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If the entire filtering system was built without the circuit, the water circulation pump would keep on going until either the battery ran out of power or the pump breaks.  There needs to be a way to control how much water should be running through the filtering/piping system.  That is what the water-sensing circuit is for.  
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If the entire filter system was built without the circuit, the water circulation pump would keep on going until either the battery ran out of power or the pump broke.  There needs to be a way to control how much water should be running through the filter/pipe system.  That is what the water-sensing circuit is for.  
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<b>General Operation:</b>
<b>General Operation:</b>
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To control when to pump in water through the filter, an Arduino was used to detect if water was in the systemIf there was water in the system, the motor would be pumping water throughIf somehow there was no more water left to be pumped, the Arduino would be able to detect this, and shut off the motor until there is some more water in the system.
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An Arduino was used to control the operation of the pumpThe Arduino and accompanying circuitry detect the presence of water and turn the pump onConversely, they turn the pump off when no water is entering the system.  
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<b>Setup and Operation:</b>
<b>Setup and Operation:</b>
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The sensor that was used to give input to the Arduino about if there was water or not is in this circuit below:
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Below is the water-sensing circuit that sends feedback to the Arduino:
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The Arduino Fio is connected at 1 of the outputs of the phototransistor to read the voltage at that point.  The Arduino Fio is programmed to cut power to the water circulation pump if there is no water in the system.  A voltage threshold is set within the program to determine what voltage read at the phototransistor output is considered to have water or no water in the system.   
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The Arduino Fio is connected at one of the outputs of the phototransistor to read the voltage at that point.  The Arduino Fio is programmed to cut power to the water circulation pump if there is no water in the system.  A voltage threshold is set within the program to determine what voltage read at the phototransistor output is considered to have water or no water in the system.   
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To ensure that the circuit is protected from the water, the entire circuit was housed in Corning pipette box to contain it from water.  Holes were drilled to move the infrared LED and phototransistor through the box and to connect the motor with the circuit.
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To ensure that the circuit is protected from water, the entire circuit was housed in a Corning pipette box.  Holes were drilled to move the infrared LED and phototransistor through the box and to connect the motor with the circuit.
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Latest revision as of 02:51, 18 October 2014

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Dry Lab

Electronics - Water Level Sensing Circuit

Why do we need it?
If the entire filter system was built without the circuit, the water circulation pump would keep on going until either the battery ran out of power or the pump broke. There needs to be a way to control how much water should be running through the filter/pipe system. That is what the water-sensing circuit is for.

General Operation:
An Arduino was used to control the operation of the pump. The Arduino and accompanying circuitry detect the presence of water and turn the pump on. Conversely, they turn the pump off when no water is entering the system.

Setup and Operation:
Below is the water-sensing circuit that sends feedback to the Arduino:
There is an infrared LED (L1) shining on a phototransistor (Q1). Physically, the transparent tubing would be placed in between the infrared LED and phototransistor, and there would be a certain amount of infrared light reaching the phototransistor. In general, a phototransistor produces current proportional to the amount of light shining on it. In this case, the phototransistor that was chosen was more sensitive to the infrared spectrum, so it will produce more current when there is more infrared light reaching it and less current when less infrared light is shining on it.

The transparent tubing will either have water running through it or not. When it has some water going through the tube, the water absorbs more of the infrared light between the LED and the phototransistor, so the reading on the voltage should be much lower than when there is no water going through the tubing.
The Arduino Fio is connected at one of the outputs of the phototransistor to read the voltage at that point. The Arduino Fio is programmed to cut power to the water circulation pump if there is no water in the system. A voltage threshold is set within the program to determine what voltage read at the phototransistor output is considered to have water or no water in the system.

To ensure that the circuit is protected from water, the entire circuit was housed in a Corning pipette box. Holes were drilled to move the infrared LED and phototransistor through the box and to connect the motor with the circuit.