Circuit Analysis

Introduction

Design of electronic and electrical circuits involved a number of stages that are critical for their successful operation. Most of the designs require a lot of analysis in order to establish that the actual intended results are obtained from the design. The design process normally starts with the simulation of the circuit under controlled environment. This implies that the designer will be required to make use of simulation tools in order to determine the overall operation of the circuit. Once the simulation results are obtained and evaluated to be positive the designer can then proceed to fabricate the circuit on a printed circuit board. Most of the laboratory experiments however make use of bread boards as part of the fabrication (Boylestad, 2014).

Each step is considered essential. The components used to build the circuit and their values are normally determined using simple laws. Some of the common laws that exist in the electrical design include Kirchoff’s law, Norton and Thevenin laws, superposition law and many others. This lab experiment is intended to establish the applicability of some of these laws. The paper will outline some of these laws and establish their applications on the circuit design. Different circuits will be built on the basis of the analysis performed using these laws. A small findings report will then be generated to reconcile the findings with the theoretical values (Boylestad, 2014).

Objective

This lab experiment is intended to establish the applicability of some of these laws. The paper will outline some of these laws and establish their applications on the circuit design. Different circuits will be built on the basis of the analysis performed using these laws. A small findings report will then be generated to reconcile the findings with the theoretical values.  The circuits will be built on Multisim. Multisim is a provides a general simulating environment for electrical circuits (Boylestad, 2014).

Evaluation of Kirchoff’s law

Kirchoff’s law is one of the basic electrical laws that define the relationship between voltage and current in a conductor. The voltage is considered to be proportional to the current as illustrated in the following expression;

V=IR

Where R is the resistance in the conductor.

The following circuit was used to establish the relationship of current and voltage as depicted from Kirchoff’s law;

As can be seen from the above figure the total amout of current I2=V2/R2=24/24=1A

Thevenin’s Equivalent and Maximum Power

The following figure can be used to illustrate the concept of the Thevenin’s Equivalent;

 

The voltage drop at point 3 is the sum of the voltage drops across all the components connected to node i.e.

V3=I1R1+I2R2=120+135=255V

Class A power amplifier

The following circuit can be used to illustrate the design that was developed in Multisim.

 

In order to compute the efficiency of the above circuit the base and collector current will have to be determined. In reference to the circuit drawn above, the collector voltage was measured to be 11.12V, the base voltage was measured to be 6mV;

The efficiency of the system can be computed as follows;

Theoretical amplification factor=12V/0.7=17.142

Actual amplification factor=11.2/0.6=18.66

Efficiency=1-(18.66-17.142)/17.142=91.11%

Class B Push-Pull Power Amplifier

The circuit constitutes a pair of complementary transistors that are biased at the cut-off point. The input voltage is normally adjusted to sufficiently forward bias each transistor within the appropriate half cycle of the input waveform (Boylestad, 2014). The following figure can be used to illustrate the circuit design that was developed in Multisim;

The input waveform that is introduced to the amplifier is normally full cycle. However, since the base of individual transistors is negative biased the signal ends up truncating the half cycle signal. As such, there remains only one half cycle that is detected at the output. However the combination of the two transistors makes the output witness full cycle at the output (Boylestad, 2014). The following figure can be used to illustrate the input and output of the two transistors of a push pull power amplifier;

Design of a signal conditioning circuit

Signal conditioning circuits are normally used to control and simulate the electrical applications that involve either too high currents or too low electrical currents that cannot be handled by the normal electronic devices. As such, the signal conditioning circuit tends to adjust the levels of the currents to meet the standards of the electronic devices. In most cases the input signal is reduced to a range of 0-5 V (Boylestad, 2014). The following circuit was developed in Multisim to simulate the signal conditioning application for industrial applications which had an internal impedance of less than 50 Ohms.

As can be seen from the above figure there were three stages that manipulated the values of the current in the circuit. The first op amp was mainly used to sum up the signals coming from different sections of the industry. The signals were then integrated to realize a linear current. The last stage inverted the signal to produce the desired output (Boylestad, 2014).

ADD inverting operational amplifier

The ADD inverting amplifier is a very useful concept that not only adds multiple signals that are introduced at the input but also inverts the output to the desired state. Depending on the number of inputs that are introduced at the input the voltage divider rule can be used to sum up all the inputs which are then introduced to the inverting terminal of the op amp. In this way the output of the op amp will be inverted (Boylestad, 2014). The following figure can be used to illustrate the concept of the ADD inverting operational amplifier.

Conclusion

The paper has considered several applications that have been developed and built in Multisim. Each of the process involved the analysis and determination of the circuit parameters that will optimize the design. Each step is considered essential. The components used to build the circuit and their values were normally determined using simple laws. Some of the common laws that exist in the electrical design include Kirchoff’s law, Norton and Thevenin laws, superposition law and many others. This lab experiment was intended to establish the applicability of some of these laws. The paper also outlined some of these laws and established their applications on the circuit design. Different circuits were built on the basis of the analysis performed using basic laws.

References

Boylestad, R. (2014). Introductory circuit analysis. 1st ed. Harlow, Essex: Pearson.

 

 

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