Introduction

The LM358 is a dual operational amplifier IC that is commonly used in various analog applications. In this experiment, we will configure one of the op-amps in the LM358 as a voltage amplifier. A voltage amplifier increases the amplitude of a signal without significantly altering its waveform, making it useful for boosting weak signals in audio and sensor applications.

Materials Required

• LM358 Operational Amplifier IC
• Breadboard and jumper wires
• Resistor (R1 and R2)
• Signal generator (for input voltage)
• Multimeter or oscilloscope (for measuring output voltage)
• Power supply (5V to 12V)

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Circuit Diagram

The following circuit diagram illustrates how to configure the LM358 as a voltage amplifier:

Pin Configuration of the LM358

• Pin 1 (OUT1): Output of the first op-amp
• Pin 2 (IN1-): Inverting input of the first op-amp
• Pin 3 (IN1+): Non-inverting input of the first op-amp
• Pin 4 (VCC+): Positive power supply
• Pin 8 (VCC- or GND): Ground or negative power supply

Steps for the Experiment

1. Place the LM358 IC on the breadboard.
2. Connect the VCC+ (Pin 4) to the positive terminal of the power supply (5V to 12V), and connect VCC- (Pin 8) to ground.
3. Connect the non-inverting input IN1+ (Pin 3) to the input voltage source (signal generator).
4. Connect the inverting input IN1- (Pin 2) to the ground through resistor (R1).
5. Connect a feedback resistor (R2) from the output OUT1 (Pin 1) to the inverting input IN1- (Pin 2).
6. Connect the output OUT1 (Pin 1) to a multimeter or oscilloscope to measure the output voltage.
7. Apply an input voltage and observe the amplified output voltage.

Explanation

In this configuration, the LM358 operates as a non-inverting voltage amplifier. The output voltage is related to the input voltage by the gain factor determined by the resistor values. The gain (A) can be calculated using the formula:

A = 1 + (R2/R1)

Where:

• R1 is the resistor connected to ground from the inverting input.
• R2 is the feedback resistor connected from the output to the inverting input.

Results and Observations

After applying the input voltage, you should observe the following:

• The output voltage (V_out) will be greater than the input voltage (V_in) based on the gain calculated.
• The amplified output will maintain the same waveform shape as the input signal.

Make sure to note the values of R1 and R2 to calculate the exact gain achieved in the experiment.

Applications of Voltage Amplifiers

Voltage amplifiers have several applications in electronics, including:

• Audio signal amplification in microphones and amplifiers
• Signal conditioning for sensors
• Transmitter circuits in communication systems
• Data acquisition systems

Conclusion

In this experiment, we configured the LM358 Operational Amplifier as a voltage amplifier. The op-amp successfully amplified the input voltage while preserving the signal's waveform, demonstrating its effectiveness in signal processing applications.