Bar-graph Temperature Monitoring System
Created: Sep 17, 2014
No description available.
Temperature sensors are used in a wide variety of scientific and engineering applications, especially measurement systems. It is a device that measures temperature or temperature gradient using a variety of different principles. This project uses an integrated circuit to sense and display the temperature.
The responsible for sensing the temperature is the IC LM35; it is a precision integrated-circuit temperature sensor, with a rate that ranged from -55°C to 150°C. It is calibrated directly in degrees Celsius (Centigrade), linearly +10 mV per °C Scale Factor. The output of LM35 is then connected to the SIGNAL pin of the IC LM3914. LM3914 is a display driver that senses analog voltage levels for ten output LEDs, LCDs, or vacuum fluorescents providing a linear analog display. It has a selectable bar or dot display modes and expandable to display one hundred output segments. Output current to the LEDs is regulated and programmable, thus, eliminating the need for resistors.
Two LM3914 are used in this project to support a 20-step output. The brightness of the output LEDs are controlled by the trimmer resistor configured at the pins REFOUT (pin 7) and REFADJ (pin 8) of the two LM3914. Another trimmer resistor is configured at pins RLO (pin4) and RHI (pin6) for offset voltage. Offset Voltage is the differential input voltage, which must be applied to each comparator of the LM3914 to bias the output in the linear region.