Designing, Implementing and Testing a Timer - Coursework Example

Designing, Implementing and Testing a Timer Designing, Implementing and Testing a Timer Experiment aims: Theaim of this experiment aimed was to: Construct an amplifier. Appraise the performance of the amplifier. Examine the roles of various components of the amplifier. Enhance my practical knowledge and technical know-how on how the amplifier works. Theory That Guided the Experiment An amplifier is a device used to enhance or increase small signal amplitude to a desirable level to the user. The amplifier increases the signal amplitude, but maintains the basic features of the small signal through a processed referred to as linearity. The higher the linear, the higher is the output signal. Through technological advancements, many kinds of amplifiers such as class A, class B, class AB, class D, class D, class DG, and class H exists in the market. Types of Amplifiers Class A Amplifiers These types of amplifiers are also known as Single-ended amplifiers and are the simplest presentation of audio amplifier. The output transistors conduct regardless of the waveform of the output signal. The amplifier is highly applicable of areas demanding high linearity because of its high liner feature. However, low frequency and power inefficiency is the main drawback for class A amplifiers. Figure 1: Section of Class A amplifier and associated waveform (Robert Nicoletti 2013 n.d). Class B Amplifiers Class B amplifiers utilize push-pull topology. They incorporate negative and positive transistors and each transistor contribute to input replication by conducting during half of the received signal, which makes Class B current efficient. Class B amplifiers are more efficient compared to class A and were developed as remedy to efficiency and heating problems in class A amplifiers. Class B amplifiers are characterized by high frequency that degrades audio signal quality. This results from cross-over point where two transistors transit from ON to OFF states. When the transistor is dealing with extremely low signals, crossover distortions can be experienced. Consequently, class B amplifiers have poor performance rates in low power gadgets. Figure 1.1: Class B amplifier and associated input and output waveforms (Robert Nicoletti 2013 n.d). Class AB Amplifiers Class AB combines features of class A and B amplifiers. They integrate sound quality and efficiency provided by class A and B amplifiers respectively. The integration of these features is made possible through making both transistors biased so that they can conduct a signal near zero. Upon the application of small signals, the two transistors will be activated and the amplifier will function in a similar way as class A amplifier. On the other hand, the application of large signal will render one transistor inactive, making the amplifier to operate like a class B amplifier. Class AB topologies are characterised by high SNR and low THD+N. Their efficiency is usually rated at about 65 percent. Class AB amplifiers are used for devices that require high fidelity such as tablets, portable media players, and cameras among others. Class AB amplifier with its input and output waveforms is as shown in figure 1.2 below. Figurer 1.2: Class AB amplifier with associated input and output waveforms. Class D amplifiers This class of amplifiers utilise PWM (pulse width modulation) to generate a rail-to-rail output signal, which has a changeable duty cycle used for estimating analog input signal. Class D amplifiers such as MAX98304 and MAX984000, are very efficient with efficiency rating of approximately 90 percent. This high level of efficiency is achieved because the output transistors usually turned on or off during normal operation. The approach used in Class D amplifiers eliminates linear region requirement for transistors and yield higher level of efficiency in different types of amplifiers. Because of its high efficiency level, Class D amplifier is used in modern moveable media such as smart phones and MP3 players among others. Figure 1.3: Class D amplifier with the associated input and output waveforms Class G amplifiers This class of amplifiers operate using the same principle as class AB amplifiers. However, Class G amplifiers use over one power supply voltage. Class G amplifiers selects a suitable power supply depending on the signal level. The amplifiers are more efficient when compared with class AB amplifiers; Class G amplifiers are more efficient owing to the fact that they use maximum power supply only when it is essential. Class B amplifiers on the other hand uses maximum voltage throughout. A section of Class G amplifier with associated input and output waveform is as shown in figure 1.4 below. Figure 1.4: A class G amplifier with associated waveforms Class DG Amplifiers Like class D, these topologies utilize pulse width modulation to produce (PWM) to yield rail-to-rail output signal with a changeable duty cycle. Unlike class D amplifiers, class DG can also sense the output signal magnitude using multilevel output stage. Switches are used to supply power so that high efficiency level can be achieved with this class of amplifiers. Class D amplifier is usually integrated into the design of class DG for high level of efficiency. Figure 1.5 below shows a class DG amplifier with associated waveform. Figure 1.5: A class DG amplifier with associated input/output waveform Class H Amplifiers In this class of amplifiers, the amplifiers reduce drop across output stage by adjusting their power supply. They use numerous digital voltage signals, including analog variable supply. This class, unlike class G, do not need many sources of power. Figure 1.6 is a presentation of a class H amplifier with associated waveforms. Figure 1.7: Class H amplifier and associated waveforms NOR Gate Oscillators NOR gate oscillator refers to a type of relaxation oscillator. In this oscillator, the RC is incorporated to reduced the rate of changes in the second NOR gate’s input pin. There is no stable state because the output is joined to the input. The voltages of the capacitor discharge towards zero up to a voltage of 2.5V in the oscillator’s waveforms then reverses. Experiment Equipment and Constituents Amplifier Circuit Design: In designing the circuit, the following equipment and parts were used: An Oscilloscope A DC power supply unit (PSU) A solderless breadboard Digital Multi-meter (DMM) Constituents/Components Resistors (Ώ): 51k, 2x 5.1, 1k, 82Ώ, Capacitors (nF): 470, 4.7, Transistors: BC109BP Methods and Procedure of the Experiment The following circuit was developed on the solderless breadboard: Figure 1.8: Amplifier circuit The values obtained from the constructed circuit above were: R1=51k, R2=5.1k, R3=1K, R4=82R, and C1-0.47uF, Vs=1 kHz and the two nodes were presented by ‘a’ and ‘b’. • The Vs value was set to 0V and measurement of the voltage at the nodes taken. • The Vs magnitude was set to 0.1V and the DC and AC the signal components measured. • R1 was disjointed. • The voltage Vb (Total) and Vb (AC) were measured. • R1 was reconnected. • C1 was detached and Vs connected to node ‘a’. • Vb (total) and Vb (AC) were measured. • C1 was reconnected and R3 amplified to 5.1k. The readings of Vb (total) and Vb (AC) were recorded. • R3 value was reset to 1k and Vs (AC) and Vb (AC) observed using an oscilloscope. • The Vs value was progressively amplified to 0.3V. In order to determine the input frequency impacts, the experimenter applied following procedures: • Reset Vs value to 0.1 V. • Vary input frequency between 10 Hz and 1 MHz while recording the value peak b (AC) for every frequency. Oscillator Design and Test This laboratory experiment aimed at: Using NOR gate to develop an oscillator Appraising the oscillator’s performance Identifying the best way to set oscillating frequency Determining sound and frequency relationship Enhancing and reinforcing our practical and technical skills Equipment’s and components Components: Capacitors (nF): 10, 100. Resistors (): 10, 68, 1k, 10k, 2100k, 220k, 620k, 1M, 3.3M, 5.6M, 10M, Transistors and Chips: BC109BP, CD4001BCN, Loud speaker 64 ohms. Equipment: The equipment used in the experiment included: Solderless breadboard Function generator (AFG) Digital multi-meter power supply unit (PSU) Oscilloscope The Procedure and Methods of the Experiment The circuit show below was constructed on a solderless breadboard Figure 1.9: Oscillator circuit The following procedures were followed in order to test for the oscillator in fig. 1.9 above: A 9V DC between pin 14 and 7 was applied to power the chip. Va, Vb and Vc waveforms were measured and recorded. The frequency of the oscilloscope recorded. In order to interface the amplifier with oscillator, the oscillator was joined to the amplifier via dashed line as indicated in figure 1.9 above. The power transmitted to the load was estimated by: Substituting the loudspeaker with load resistor R (load) =10R. Measuring the waveform voltage drop across R (load) and Vload and Measuring the top level of Vload, V (top). In assessing the effect of power on the load’s amplitude, the R=1k, 10k, 620k and 3.3M, the Vc were observed and frequency recorded. In order to enhance the tune, the element Reset, R=100 in figure 1.9 was rebranded R4 in figure 2.0 Figure 2.0 This circuit was constructed on a breadboard. Values R7=620, 5.6M and 10M were applied to evaluate the impact of the values of the components on the tune. Experiment Observations, Findings, Results and Discussion Amplifier design and test When the DC voltage is biased using an oscilloscope or a voltmeter, we can get the values for the voltage as shown below: Consequently, V (total) = 724mV, which is the Peak AC value. Therefore, peak DC = 8.60V. When R1 is detached, peak-to-peak voltage changes to 24mV. Based on the big decrease in the value, it can be deduced that R1 is a crucial component of the circuit. Altering the value of R1 leads to a fall in voltage value as well as a decline in the peak-to-peak value. Increasing R1 amplifies the peak-to-peak reading to 450mV while the input voltage rises to 4.11V. When R1 is reconnected and signal generator used in place of C1, a decrease of 550mV is observed in the input while AC peak-to-peak voltage remains unchanged. The output signal value varies from positive to negative. Part 3 Upon turning on the 9V oscillator, a waveform that is sawtooth in nature is seen at the oscilloscope. Vb and Vc generate waves with positive and negative amplitudes respectively. The observed frequency is 618.1Hz while theoretical frequency is usually 1 kHz. The discrepancy in the frequency value can be attributed to the capacitive feature in the chip circuit. The total value of capacitance in the circuit is more than 10nF. The loudspeaker sound remains unchanged, which is a clear indication the oscillator is functioning according to the expectation. The amplifier’s input and output are in mA and Am respectively. To estimate the power transmitted to RL (load), Note: a factor of 2 is used because it is a peak-to-peak power. The effect of power on the system: The V (top) as well as the speaker begins to decrease progressively. When the power supply is reduced below 3V, the speaker produces no sound. The table below indicates frequency values obtained at various voltages. Resistance (ohms) Vc (frequency) 1K 40 MHz 10K 5.6MHz 620R 100Hz 3.3 18.8Hz Table 1.0 Resultant frequency at various voltage levels From table 1.0 above, it can be deduced that the lower the voltage value, the lower is the pitch of the speaker. This results from varying resistor values in the circuit. In the circuit 2.0, the speaker was oscillating indicating that the oscillation time declines with increase in the value of the resistor. The choice of a 64Ω speaker was based on its ability to accommodate more power load and higher efficiency compared with an 8Ω speaker. Bibliography Anil KM 2007, ‘Digital Electronics, Principle, Devices and Application’, John Wiley and Son Limited, England Chi-Tsong C 2002, ‘Analog and Digital Control System Design’, Saunder college publishing. Barry P 1998, ‘Fundamentals of Digital Electronics’, National Instrument Corporation John B 2007, ‘Electrical and Electronics Principals and Technology, third edition’, Newnes Elsivier, UK. Robert N 2013, ‘Audio Amplifier Basics, select the best topology for your design’, Viewed April 14, 2013 Read More