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Unformatted text preview: Creating I-V Curves and Load Line Calculation Matthew Beckler [email protected] EE2002 Lab 003 March 6, 2006 Abstract As an introduction to non-linear circuit devices, the electrical prop- erties of both an incandescent lamp and silicon diode are investigated. Using a load-line analysis, the operating current is calculated and verified for the lamp. The silicon diodes are used in a variety of arrangements to produce different clipping circuits. 1 Introduction In the world of electric circuit analysis, linear devices are wonderful. They permit the use of many important solution methods, such as Kirchhoff’s two laws, the node-voltage and mesh-current methods, and the super-positioning principle. A system of linear devices is so well-behaved that man circuits can be reduced down to a Thevenin or Norton equivalent circuit, greatly simplifying subsequent calculations. Unfortunately, many common devices are classified as ‘non-linear‘ devices. Unless simplifying assumptions are made, circuits involving these non-linear devices are much more difficult to analyze. For simple non- linear circuits, such as a light bulb or LED circuit, we can use a method known as ‘load-line‘ analysis to find the circuit’s operating parameters. For other non- linear devices, such as a silicon diode, we can use a function generator and oscilloscope to observe a circuit’s effect on an input signal. Using the special, non-linear properties of these diodes, a number of interesting modifications can be performed on a signal, mostly in the way of clipping the input voltage at a specific level. 1 2 Experiments 2.1 Current Versus Voltage Relationship The first step in conducting a load-line analysis is to obtain the raw current versus voltage relationship for the device in question, here, an incandescent lamp. The circuit was constructed as such: Figure 1: Circuit Schematic - Experiment 1 The voltage was varied in two volt increments between 2 and 60 volts. The measured current is summarized in the following table: Voltage (V) Current (mA) Voltage (V) Current (mA) 2 4.3 32 21.1 4 6.3 34 21.9 6 7.8 36 22.7 8 9.2 38 23.4 10 10.5 40 24.2 12 11.7 42 24.9 14 12.8 44 25.6 16 13.8 46 26.3 18 14.9 48 27.0 20 15.9 50 27.7 22 16.8 52 28.4 24 17.7 54 29.0 26 18.6 56 29.7 28 19.5 58 30.3 30 20.3 60 30.9 A chart of the previous data is useful to observe the behavior of the device in response to various input voltages, and is included on the next page of this document. The current values appear to be levelling-off as the voltage continues to increase linearly. If this trend continues, the device will reach an upper-limit to the current it will allow. This chart is very important in calculating the...
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This note was uploaded on 01/19/2011 for the course EE 2002 taught by Professor Paul during the Spring '10 term at Minnesota.
- Spring '10