Understanding the LM35 Sensor

The.C°0 LM35 is a precision integrated - circuit temperature sensor. Its output voltage is linearly proportional to the Celsius (Centigrade) temperature. The output voltage changes by 10mV per degree Celsius change in temperature, with an output of 0V at 0°C.

RequirtnempiuqEed Equipment

  • Multimeter: A digital multimeter is preferred for its high accuracy and ease of reading. Make sure it has a voltage measurement function.
  • Power Supply: The LM35 typically operates with a supply voltage ranging from 4V to 30V. You can use a regulated power supply or a battery.
  • Breadboard and Wires: These are used to connect the components together in a safe and organized manner.

Measurement Steps

Circuit Connection
  1. First, place the LM35 on the breadboard. The LM35 usually has three pins: VCC (power supply), GND (ground), and Vout (output voltage).
  2. Connect the VCC pin of the LM35 to the positive terminal of the power supply. The voltage of the power supply should be within the operating range of the LM35.
  3. Connect the GND pin to the negative terminal of the power supply.
  4. Leave the Vout pin unconnected for now.
Multimeter Setup
  1. Turn on the multimeter and set it to the DC voltage measurement mode. Select an appropriate voltage range. Since the output voltage of the LM35 is relatively low, you may start with a range of 0 - 2V.
  2. Connect the red probe of the multimeter to the Vout pin of the LM35.
  3. Connect the black probe of the multimeter to the GND pin of the LM35.
Taking the Measurement
  1. Apply power to the circuit. Once the power is on, the LM35 will start to sense the temperature and generate an output voltage.
  2. Read the voltage value displayed on the multimeter. This value is the output voltage of the LM35 sensor.

Calculating the Temperature

If you want to convert the output voltage to temperature, you can use the following formula:
Temperature(∘C)=0.01V/∘COutputVoltage(V)
For example, if the output voltage is 0.25V, then the temperature is 0.01V/∘C0.25V=25∘C.

FAQ

  • Q: Can I use an analog multimeter to measure the output voltage of the LM35?
    A: Yes, you can use an analog multimeter. However, digital multimeters are more accurate and easier to read, especially for small voltage values.
  • Q: What if the measured voltage is not within the expected range?
    A: There could be several reasons. Check the power supply voltage to ensure it is within the operating range of the LM35. Also, make sure all the connections are correct and there are no loose wires.
  • Q: Can I measure the output voltage of multiple LM35 sensors simultaneously?
    A: Yes, you can measure multiple sensors simultaneously. You need to connect each sensor's Vout pin to a separate input channel of a multimeter or a data acquisition system if you want to monitor them all at once.