Como medir la temperatura usando el sensor LM35 y un Op-Amp!

Takeaways

• 😀 The temperature is measured using an LM35 sensor, which outputs 10 millivolts per degree Celsius.
• 😀 The LM358 operational amplifier (op-amp) is used to amplify the sensor's signal and function as a comparator.
• 😀 The op-amp requires a preset or potentiometer to adjust the reference voltage for comparison with the sensor output.
• 😀 The LM358 op-amp has two internal amplifiers, but only one is used in this circuit.
• 😀 The output of the op-amp is a positive or negative voltage depending on the comparison between the sensor and reference voltage.
• 😀 Two LEDs are used to visualize the operation of the op-amp comparator, changing states based on the temperature input.
• 😀 The circuit is powered by a 6V supply, which suits both the sensor and the op-amp.
• 😀 To use the system, the preset is adjusted to set a reference voltage, such as 400 millivolts.
• 😀 As the temperature increases, the sensor output voltage rises, and when it surpasses the reference, the op-amp toggles the LEDs.
• 😀 This setup can be used to trigger electrical loads, such as relays, by utilizing the op-amp's output to activate transistors or other components.

Q & A

What is the purpose of the LM35 sensor in the circuit?

The LM35 sensor is used to measure temperature. It provides an output of 10 millivolts per degree Celsius detected.

Why is an operational amplifier (LM358) used in this circuit?

The LM358 operational amplifier is used to amplify the signal from the LM35 temperature sensor and also functions as a comparator to compare the sensor's output voltage with a preset voltage.

How does the operational amplifier work as a comparator in this setup?

The operational amplifier compares the voltage from the LM35 sensor (input) with the voltage from a preset or potentiometer (set reference voltage). Based on this comparison, it changes the output to activate devices such as LEDs or relays.

What role does the potentiometer play in the circuit?

The potentiometer is used to set a reference voltage, which determines the temperature threshold. It acts as a voltage divider between the positive and negative supply to set the comparison value for the operational amplifier.

How does the circuit indicate a change in temperature?

The circuit uses LEDs to indicate changes in temperature. When the sensor's output voltage exceeds or drops below the preset reference voltage, the LEDs change states to show the comparison result.

What happens when the sensor's output voltage is greater than the preset voltage?

When the sensor's output voltage is greater than the preset voltage, the operational amplifier changes its output, which can activate connected components such as LEDs or relays.

Why is the circuit powered at 6 volts?

The LM35 sensor and the LM358 operational amplifier both function within a 6-volt operating range, making 6V a suitable power supply for both components.

What is the significance of the 10 millivolt per degree Celsius output from the LM35?

The 10 millivolt per degree Celsius output from the LM35 means that for every 1°C increase in temperature, the sensor's output increases by 10 millivolts. This value is used by the comparator to detect temperature changes.

What could be the practical applications of this temperature sensing circuit?

This temperature sensing circuit could be used in automation systems, such as controlling fans, heating elements, or other devices based on temperature, through the use of relays or transistors.

How can the circuit be modified to handle larger loads?

The circuit can be modified to handle larger loads, such as relays or high-power components, by using transistors or other switching devices to amplify the current and control larger electrical devices.