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APSC 100 Project #31: Home Weather Station Group 31Q Billy Smith Jacob Black George McDonald Keith Brown Supervised By Dr. Geoff Lockwood Project Manager Bob November 2, 2002 APSC 100 Project #31: Home Weather Station Presentation Overview 1. What We Learned 2. Our Goal 3. Preliminary Design 4. Components 5. Progress Report APSC 100 Project #31: Home Weather Station What We Learned Tutorial #1: - construction of circuits - methods for measurement of voltage, current, and resistance Tutorial #2: - operational amplifiers Tutorial #3: - analog-to-digital converters - seven-segment displays APSC 100 Project #31: Home Weather Station Our Goals 1. Learn to build and analyze simple electronic circuits. 2. Produce an inexpensive weather station suitable for home use, with the capability to measure readings in the ranges of: 1. -40oC to +40oC 2. 0% to 100% humidity (±2%) APSC 100 Project #31: Home Weather Station Preliminary Design Our circuit will contain the following: • LM555 Timer/Square Wave Clock • AD7819 Analog-to-Digital Converter • Temperature Transducer Circuit • Humidity Transducer Circuit APSC 100 Project #31: Home Weather Station Components of Circuit 1. LM555 Timer/Square Wave Clock 2. AD7819 Analog to Digital Converter 3. Temperature Transducer Circuit 4. Humidity Transducer Circuit APSC 100 Project #31: Home Weather Station Component #1 (LM555 Timer/Square Wave Clock) - - - used to generate a squareroot wave sends an analog clock signal to the AD converter square-root wave produces intervals of reading/sampling of the analog input signal Pictures courtesy of National Semiconductor APSC 100 Project #31: Home Weather Station Component #2 (Analog-to-Digital Converter) An AD789 linked with the DM9368 common-cathode display driver and a seven segment display -Convert analog signals from the transducers to binary codes -Convert binary code into a digital display Picture courtesy of National Semiconductor APSC 100 Project #31: Home Weather Station Component #3 (Temperature Transducer) - - - LM35 precision integrated-circuit temperature sensor ±0.5oC accuracy guaranteed (at +25oC) Rated for –55oC to +150oC range Picture courtesy of National Semiconductor APSC 100 Project #31: Home Weather Station Minimum Supply Voltage Our given temperature range produces a fluctuation in signal of ±1V. An amplifier may be required to make this signal usable for our purposes. Picture courtesy of National Semiconductor APSC 100 Project #31: Home Weather Station Component #4 (Humidity Transducer) - HIH-3605-A transducer circuit allows us to read the relative humidity - Send an analog signal to the AD (Analog/Digital Circuit) converter Picture courtesy of National Semiconductor APSC 100 Project #31: Home Weather Station Output Voltage - Transducer outputs within target range of AD Converter Picture courtesy of National Semiconductor APSC 100 Project #31: Home Weather Station Final Progress Report 1. The clock and Analog/Digital Converter have been constructed and tested 2. Next we plan to implement the temperature and humidity transducers 3. Group cooperation is satisfactory and there are no team issues to report