3 Review(s)

This temperature meter uses the precision micro power centigrade sensor IC LM35. The output voltage of the IC is linearly equal to +10Mv per degree centigrade. The temperature level is displayed through LED read out. The circuit uses the precision temperature IC LM35. This three pin transistor like IC give output linearly equal to +10mV per degree rise in temperature. It can measure temperature between -4 degree to +110 degree centigrade. Its related type LM34 is Fahrenheit sensor and its output is equal to -10mV per degree Fahrenheit. Output of IC LM35 is directly given into the input of the display driver IC LM3914. It is a monolithic integrated circuit with 10 active low outputs that can drive 10 LEDs directly without a current limiting resistor.The internal circuitry of the IC adjusts the current passing through the LEDs. The input of LM 3914 is very sensitive. Here only 6 outputs are used to drive 6 LEDs. More LEDs can be included in the remaining outputs if required. As the IC LM35 senses temperature rise, LEDs one to six light up.