Objective
The objective of this experiment is to investigate the characteristics and performance of thick-film resistors under high voltage conditions. This experiment will demonstrate how thick-film resistors handle power dissipation and their reliability in high voltage applications.
Materials Needed
- Thick-film resistors (rated for high voltage)
- High voltage power supply (up to 500V)
- Multimeter (for measuring voltage and current)
- Breadboard or high voltage testing board
- Heat sink (if necessary for power dissipation)
- Safety equipment (gloves, goggles, etc.)
- Optional: a resistor load (e.g., an incandescent bulb)
Theory
Thick-film resistors are manufactured by screen printing a thick layer of resistive material onto a ceramic substrate. They are commonly used in applications requiring high voltage and power handling capabilities. The resistive material can withstand higher temperatures and voltages compared to thin-film resistors, making them suitable for power applications.
The power dissipation of a resistor can be calculated using the formula:
P = V^2 / R
Where **P** is the power (in watts), **V** is the voltage across the resistor (in volts), and **R** is the resistance (in ohms).
Steps
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Set Up the Circuit
Connect the thick-film resistor to the high voltage power supply on the testing board. Ensure that all connections are secure and that the resistor is rated for the applied voltage.
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Safety Checks
Before applying power, double-check the circuit for any potential short circuits. Ensure all safety equipment is worn, including gloves and goggles.
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Initial Measurements
Measure the resistance of the thick-film resistor using a multimeter to confirm its rated value. Record this value for analysis.
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Apply High Voltage
Gradually increase the voltage on the power supply to the desired level, monitoring the circuit closely for any signs of overheating or instability.
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Measure Voltage and Current
Using the multimeter, measure the voltage across the thick-film resistor and the current flowing through the circuit. Record these values in a data table for analysis.
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Calculate Power Dissipation
Using the recorded voltage and resistance, calculate the power dissipation of the thick-film resistor using the formula provided in the theory section.
Data and Calculations
Record the voltage and current at various high voltage levels. Below is a sample data table:
| Voltage (V) | Current (A) | Resistance (Ω) | Power Dissipation (W) |
|---|---|---|---|
| 100 | 0.1 | 1000 | 10 |
| 200 | 0.2 | 1000 | 40 |
| 300 | 0.3 | 1000 | 90 |
Power dissipation can be calculated for each voltage level using the formula:
P = V^2 / R
Conclusion
This experiment demonstrates the performance of thick-film resistors in high voltage applications. Their ability to handle high power levels while maintaining stability is crucial for various electronic applications. Understanding the behavior of these resistors under high voltage conditions is essential for designing reliable and safe electronic circuits.