55 lines
3.8 KiB
Markdown
55 lines
3.8 KiB
Markdown
# Differential Amplifier for mV/V Instrumentation
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## Project Overview
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This project focuses on developing a differential amplifier tailored for mV/V instrumentation, specifically designed for use with load cells and other precision sensors. The amplifier boosts the signal to a level appropriate for reading by standard analog-to-digital converters (ADCs), like those found in Arduino platforms, providing a significant gain while also adjusting the zero-level output voltage for optimal ADC utilization.
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## Key Features
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- **High Gain Capability**: Achieves a gain factor of approximately 100, ideal for amplifying millivolt signals from precision sensors to usable levels.
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- **Output Offset Adjustment**: Ensures that a 0 mV differential input translates to a 2.5V output, maximizing the dynamic range of ADCs that operate within a 0-5V range.
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- **Calibration with Analog Discovery 3**: Leverages the capabilities of the Analog Discovery 3 to automate the calibration process, enhancing the accuracy and reliability of the amplifier.
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## Calibration Methodology
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Calibration is conducted using the Analog Discovery 3, which acts as both a signal generator and data logger, ensuring precise control and measurement of input-output relationships. The calibration script must be loaded into the Digilent WaveForms software.
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### Steps Involved:
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1. **Signal Generation**: Differential voltages ranging from -20mV to +20mV are generated in increments (e.g., 0.5mV steps) to simulate sensor output.
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2. **Data Logging**: During each input step, the amplifier's output is sampled over a 1-second interval to obtain average values.
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3. **Repeated Measurements**: Multiple sweeps across the entire voltage range are conducted to ensure data consistency and reliability.
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4. **Data Analysis**: A linear regression analysis is applied to the logged data to determine the amplifier's gain and offset, along with their respective uncertainties.
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## Implementation Details
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The calibration script automates the signal generation, data logging, and analysis process, providing a robust framework for ensuring the amplifier's accuracy. This script is located at `src/analog_discovery_code`.
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- **Customizable Parameters**: Users can set the voltage range, step size, and the number of sweeps.
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- **Efficient Data Handling**: The script logs both input and output values for each voltage step, ensuring thorough data collection.
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- **Advanced Analysis**: Uses linear regression to compute key parameters (gain and offset), incorporating uncertainty analysis to gauge calibration precision.
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### Workflow Example:
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1. **Initiate Calibration**: Load the calibration script into the Digilent WaveForms software and run it to start the process.
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2. **Configure Parameters**: Define the input sweep range, step size, and loop count.
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3. **Data Acquisition**: Log input and output voltages, averaging over defined intervals.
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4. **Compute Results**: The Python script `src/analyze_data.py` analyzes the data, calculates gain and offset, and reports results with uncertainties.
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## Visual Documentation
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Below are visual representations of the amplifier's performance, illustrating the calibration results and the physical setup:
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<img src=readme_media/amplifier_board.jpg width="500">
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### Calibration Outputs
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- **Amplifier Gain vs Input**: Displays the relationship between input voltage and amplifier gain.
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<img src=example_calibration/images/Amplifier%20Gain%20vs%20Input.png width="500">
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- **Amplifier Output vs Input**: Shows how the output voltage varies with input signal.
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<img src=example_calibration/images/Amplifier%20Output%20vs%20Input.png width="500">
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This comprehensive documentation and systematic approach ensure that the differential amplifier is well-suited for high-precision applications, offering reliable performance tailored for mV/V instrumentation.
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