Objective
The objective of this experiment is to design and implement a Pi filter to smooth out the output voltage in a power supply circuit, thereby reducing ripple voltage and providing a more stable DC output.
Components Required
- 1 x Resistor (R1)
- 2 x Capacitors (C1, C2)
- 1 x Inductor (L1)
- 1 x Transformer (optional, for AC to DC conversion)
- 1 x Bridge Rectifier (e.g., 1N4007)
- 1 x Multimeter or Oscilloscope
- Connecting Wires
- Breadboard (optional)
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Theory
A Pi filter consists of two capacitors and one inductor arranged in a "π" configuration. It is used to smooth the rectified output from a power supply. The basic function of the Pi filter is to reduce the ripple voltage by allowing low-frequency signals (DC) to pass while blocking high-frequency noise.
The transfer function can be approximated as:
- Ripple Voltage Reduction: The ripple voltage \( V_r \) can be calculated using the formula:
- \( V_r = \frac{I}{f \cdot C} \)
- Where: \( I \) = load current, \( f \) = frequency of the ripple, \( C \) = capacitance.
Circuit Diagram
Experimental Setup
1. Connect the components according to the circuit diagram, ensuring all connections are secure.
2. If using an AC power source, connect the transformer to reduce the voltage to a suitable level.
3. Connect the output of the rectifier to the Pi filter circuit.
4. Connect the output of the Pi filter to the multimeter or oscilloscope for measurement.
Procedure
- Set up the circuit according to the circuit diagram.
- Power the circuit and observe the output voltage using the multimeter or oscilloscope.
- Measure the ripple voltage at the output before and after the Pi filter.
- Document the results and calculate the ripple voltage reduction using the provided formula.
- Experiment with different load currents and observe how the ripple voltage changes.
Results and Observations
Document the output voltage and ripple voltage measurements for various load currents. Analyze how the Pi filter improves the voltage stability.
Conclusion
This experiment demonstrates the effectiveness of a Pi filter in smoothing out the output voltage of a power supply. The reduction in ripple voltage illustrates the importance of filtering in power supply circuits to ensure stable DC outputs.
