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Package Deals | Optional Features
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Tire Mileage Monitoring This tiny device (smaller than a postage stamp) was designed to count the number of revolutions that a tire went through (therefore it's mileage) in it's life time. In it's final configuration it was a patch located on the inside of the tire. There are no batteries. A peizoelectric plastic strip that generates a small current when flexed is the power source.  As the tire rotated (flexing the plastic strip) power is generated and stored on capacitors. The microcontroller used the voltage spike from the plastic strip as both a power source and a counting source. The microcontroller contained an internal Electrically Alterable Read Only Memory that stored the counts when the tire stopped rotating. It only took 10 rotations of the tire at 3 MPH to activate counting. To read the total rotations, a Radio Frequency source was used. The RF was received with a small antenna which activated the device. The device transmitted the information to the reader by loading the antenna thereby loading the source. In the final design the back side of the board was the antenna and the crystal was replaced with an RC network for cost reduction.
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