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PC_TEMPERATURE_INTERFACE

2014-11-15 02:56  
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PC_TEMPERATURE_INTERFACE
PC_TEMPERATURE_INTERFACE
PC_TEMPERATURE_INTERFACE
This simple temperature interface covers a range of 0 to 51°C. Dual balanced 12-V supplies were used to power the prototype, but dual 5-V supplies should just about suffice. IC1 is the temperature sensor. Over this range of temperatures, the LM35CZ should work well. The output from IC1 feeds into a noninverting-mode amplifier based on IC2. The closed-loop voltage gain of the amplifier is set by resistors R1 and R2 and preset VR1. The latter is adjusted to give a voltage gain of 5. VR1 is given the correct setting by first subjecting the sensor to a temperature, which is equal to about 50 or 100 percent of the full-scale value (i.e., about 20 to 51°C.). In most cases, the room temperature will be about 20 to 25°C, which will suffice. An accurate thermometer is used to measure the room temperature, and then VR1 is adjusted for the appropriate reading. The following GW Basic or Q BASIC program reads the temperature sensor and prints the temperature on the screen: