Vehicle Froost Box Essay Research Paper Research

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Vehicle Froost Box Essay, Research Paper Research Report The system I choose to research is a simple ?open-looped system? called the ?Vehicle Frost Box?. This system is used to informing motor vehicle operators that likely conditions for icy roads are developing. Black ice cannot be seen and is a prime contributor to vehicle accidents during the winter months. If used, this simple system could actually save precious time, money and physical injury. For system development, the ?Problem Statement? is; ?Black ice cannot be seen on roads, causing safety hazards for drivers.? Next, the ?Need Statement? is; ?We need a way to determine when favorable weather conditions exist to form black ice on roads?. Last, the ?Requirement Statement? consists of the following: the system must be

cheep, reliable, and linear, with a low thermal mass allowing a quick response to variation in air temperature. There is a system already in use that is cheep. This system uses a liquid crystal strip attached to the drivers wing mirror. However, this attachment location is too high from the ground to properly determine road conditions. Additionally, some cars have heated mirrors, which would render this system useless. A silicone semiconductor junction, in the shape of a diode was chosen to build the design around. This option filled all the requirements listed in the ?Requirement Statement?. Optional sensor devices were thermistors, thermometers, and thermocouples. These options were discarded because of high cost. The basic design of the frost box follows:  Powered by

vehicle ignition  Uses a remote temperature sensor mounted close to the road surface  Display is a single tri-color Light Emitting Diode (LED)  Mounted on the drivers console  Three modes indicating variations of external temperature  * 4C = steady green light  * 4C = steady red light  * 0C = alternating green & red light The design is based around a type 324 integrated circuit that contains four op.amp blocks. Each op.amp block is used in a different way to process the sensor signal. The first, IC1a, creates a constant current through the sensor diode, D1. IC1b amplifies the diode voltage variations, applies voltage of a sensible magnitude and moves the voltage in the right direction. The voltage output is directly proportional to the temperature

readings from the sensor. IC1c is a comparator that compares the voltage output of IC1b to the desired thresholds of 0C and 4C and controls the red/green LED switch over at 4C. IC1d is a secondary comparator, configured as an oscillator, which controls the red/green LED when the readings fall below 0C. The simple design of the frost box lends itself to construction by a ?do it yourself? person. A materials list is available along with instructions and the recommended layout for component installation. Additional advice on technique is provided in the instructions to ensure success. Several tests should be conducted prior to installation and use. First, using a voltage meter, the resistance across the power leads, and between the +5V and 0V lines on the circuit board should be

measured to see if there are any shorts. Then with the meter check that IC1a is receiving a 5V supply across its power pins (11 and 4). If things check O.K., remove the power and install IC1a in its socket. Once all the components are installed together, it?s time to calibrate VR1 and perform an integrated system test. To simulate weather conditions below 0C, place some ice from the freezer with some water in a pitcher. A thermometer is used to validate the temperature of the chilled water used in testing. Once testing conditions are set up, apply power to the circuit. Then dip the diode in the water, being careful to keep the sensor away from the ice. Calibrate VR1 by adjusting the preset pot until the LED is flashing red/green. After calibration is complete, remove the diode