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Unformatted text preview: 1 UNIVERSITY OF CALIFORNIA, BERKELEY EE 4 0 Summer 2008 Lab 1 Introduction to Circuits and Instruments Guide 1. Objectives The electronic circuit is the basis for all branches of electrical engineering. In this lab, basic electronic circuit theory, electronic and photonic devices will be introduced and employed. Fundamental testing equipment will be used to measure and characterize simple circuitry. In the handson lab, you will apply these basic theories to the devices and components provided to design simple circuits. 2. Basic circuit theory and devices In this section, some basic circuit theory will be presented first. You will need to apply this to the following handson lab to design your circuit. Simple electronic and photonic devices such as resistors, light emitting diodes (LEDs) and speakers/microphones will also be discussed and used in the lab. Before doing the lab, please read through this section carefully and complete the prelab to test your understanding of the material presented here. (1) Ohm’s Law: V = IR Current (denoted I ) and voltage (denoted V ) are two major quantities that are used to study electronic circuits. Current is the amount of charge passing through a certain area in a unit time period, while voltage describes the electrical potential drop across any two nodes in a given circuit. Ohm’s Law states that the voltage V across an ideal resistor is proportional to the current I through the resistor. The constant of proportionality is the resistance R of the resistor. I R + V I V Slope = R IR V = I R + V I R + V I V Slope = R I V Slope = R IR V = Figure 1 2 (2) Series and parallel connections A circuit usually contains many devices connected in different fashions. Two basic types of configuration are series and parallel. As shown in the figure below, when the devices are connected in series, the current going through them is the same ( I = I 1 = I 2 ), and the total voltage across both devices is the sum of the voltage across each device ( V = V 1 + V 2 ). However, for parallel connection, the voltage across the devices is the same ( V = V 1 = V 2 ) since they share the same nodes across which the potential drop is measured, and the total current running through all the devices is the sum of the current in each branch ( I = I 1 + I 2 ). Device 1 Device 2 I 1 I 2 I = I 1 = I 2 V 1 V 2 V = V 1 + V 2 Series : Parallel : Device 1 Device 2 V 1 V 2 I 1 I 2 I I V V I = I 1 + I 2 V = V 1 = V 2 + _ + _ Device 1 Device 2 I 1 I 2 I = I 1 = I 2 V 1 V 2 V = V 1 + V 2 Series : Parallel : Device 1 Device 2 V 1 V 2 I 1 I 2 I I V V I = I 1 + I 2 V = V 1 = V 2 + _ + _ Figure 2 Now let us examine the resistive circuits shown below. I 1 I 2 V 1 V 2 Series : I V R 1 R 2 Parallel : V 1 V 2 I 1 I 2 I V R 1 R 2 I 1 I 2 V 1 V 2 Series : I V R 1 R 2 I 1 I 2 V 1 V 2 Series : I V R 1 R 2 Parallel : V 1 V 2 I 1 I 2 I V R 1 R 2 Parallel : V 1 V 2 I 1 I 2 I V R 1 R 2 (a) (b) Figure 3 3 In (a), based on Ohm’s law, V 1 = R 1 I 1 , V 2 = R 2 I 2...
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 Summer '07
 ChangHasnain
 Electrical Engineering, Resistor, Electrical resistance, Voltage source, Series and parallel circuits

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