Single Stage H Biased Amplifier Biology Essay

Single Stage H Biased Amplifier Biology Essay The objective of this laboratory exercise was to design, simulate, build and test a single stage H- biased amplifier to design specifications and requirements. The design specified a voltage gain of 50 be obtained, a lower cut off frequency of 100Hz and maximum symmetrical swing. An NPN 2N3904 transistor was to be used, with a supply voltage of 15volts. A 100kà ¢Ã¢â‚¬Å¾Ã‚ ¦ load resistor was also required in the design. The values for the components involved in the design were first calculated, using logical deductions, and then simulated using the software Multisim. The H- biased amplifier was then built on a solder less bread board. The various values were measured in the laboratory using the appropriate equipment. Analysis of the calculated, simulated and measured values was done. The results were discussed and used to determine whether the specifications were met. This laboratory exercise was an introduction to the design of electronic devices. Valuable knowledge and practical skills were gained in performing this exercise. This knowledge would prove useful in future designs. Contents Table of Figures List of Tables List of Symbols/ Abbreviations A Amperes AC Alternative Coupling Av Voltage Gain BJT Bipolar Junction Transistor Ci Input Capacitor Co Output Capacitor CE Emitter Capacitor (By pass) dB Decibels DC Direct Coupling f Frequency hfe Current Gain hie Emitter Input Impedance Hz Hertz I Current IB Base Current IC Collector Current IE Emitter Current I1 Current through R1 I2 Current through R2 K.V.L Kirchhoffs Voltage Law k- Kilo m milli R Resistance R1 Resistor 1 R2 Resistor 2 RE Emitter Resistor Re Unbypassed Emitter Resistor RE* Recalculated Emitter Resistor RC Collector Resistor RL Load Resistor RTH Thevenins Equivalent Resistance V- Voltage VB Voltage across Base VBE Base Emitter Voltage VCC Supply Voltage VCE Voltage across Collector and Emitter VRC Voltage across Collector Resistor VRE Voltage across Emitter Resistor VTH Thevenins Equivalent Voltage VR1- Voltage across R1 VR2 Voltage across R2 XCE Reactance of CE XCi Reactance of Ci XCo Reactance of Co Zi Input Impedance Zo Output Impedance à ¢Ã¢â‚¬Å¾Ã‚ ¦ Ohms Introduction The following gives a brief description of the Bipolar Junction Transistor (BJT). A Bipolar Junction Transistor is an active semiconductor device formed by joining two P-N junctions whose function is amplification of an electric current. (Seale 2003). The transistor can also be used for the purposes of switching. However, in this exercise, the focus is centered on the application of amplification. A bipolar junction transistor consists of three regions of doped semiconductors. P- type and N- type semiconductor materials are alternatively joined together to form the transistor. This therefore results in 2 PN junctions. The transistor consists of three regions, namely, the emitter, the base and the collector. The diagram below illustrates the basic structure of a transistor, showing the PN junctions and the emitter, base and collector. BJT layers Figure : Transistor Source: http://encyclobeamia.solarbotics.net/articles/bip_junct_trans.html (accessed November 17th 2010 at 5:44pm.) From the diagram it is easily seen that one P-N junction is between the emitter and the base and the other P-N junction is between the collector and the base. Since the emitter and collector are usually doped somewhat differently, they are rarely electrically interchangeable. (Seale 2003). The base also forms the mechanical base for the structure. (Seale 2003). The base region is made as thin as possible (about 10-6m) to get a reasonable good levels of current gain.(Seale 2003). Furthermore, it is made thin for easier passage of electrons through the base region to the collector. Bipolar transistors are either NPN or PNP, based on the arrangement of their N-type and P-type materials. An NPN transistor is formed by sandwiching a very thin region of P-type between two regions of N-type materials. Figure 2 below shows an NPN transistor, while figure 3 shows the symbol used to represent it. NPN layers Figure : NPN Transistor Source: http://encyclobeamia.solarbotics.net/articles/bip_junct_trans.html (accessed November 17th 2010 at 5:44pm.) Figure : NPN Transistor SymbolImage Source: http://encyclobeamia.solarbotics.net/articles/bip_junct_trans.html (accessed November 17th 2010 at 5:44pm.) Similarly, a PNP transistor is formed by sandwiching a very thin region of N-type between two regions of P-type materials. Figure 4 below shows the PNP transistor, while figure 5 shows the symbol used to represent it. Figure : PNP TransistorPNP layers Source: http://encyclobeamia.solarbotics.net/articles/bip_junct_trans.html (accessed November 17th 2010 at 5:44pm.) Figure : PNP Transistor SymbolImage Source: http://encyclobeamia.solarbotics.net/articles/bip_junct_trans.html (accessed November 17th 2010 at 5:44pm.) (It should be noted that the circle around the transistor usually not seen when the transistor is drawn in circuit diagrams.) It is clear that the distinguishing characteristic of the two transistor symbols is the direction of the arrow. A transistor in a circuit will be in one of three conditions: Cut off (no collector current). In this region it can be used as switch. In the active region (some collector current, more than a few tenths of a volt above the emitter. In this region, it can be used for amplifier applications. In saturation (collector a few tenths of a volt above emitter), large current useful for switch on applications.(Nave) The figure below illustrates these regions of operation. http://hyperphysics.phy-astr.gsu.edu/hbase/solids/imgsol/tran6.gif Figure : Regions of Operation of the Transistor Source: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/trans2.html#c4 , accessed November 17th 2010 at 5:40 pm. A NPN transistor was used to in this laboratory exercise to act as an amplifier. The transistor must therefore be in the active region. Background Theory The following describes the reasons for the choice of biasing arrangement and type of configuration. Possible applications of the design project are also included. For transistors to produce amplification, an operating point must first be established. Since a transistor can act as an amplifier in the active region, it is here that the operating point is established. This operating point is fixed, and so it is referred to as a quiescent point (Q point). This is known as biasing. This operating point is the point where the applied signal would be amplified. Therefore it is required that this point be constant. Biasing is the operation of setting an operating point within an operating range and the purpose of bias design is to set the collector current of a transistor to a specific value and keep deviations due to temperature and beta variations to a specified minimum.(Kuhn 2008) Biasing can take two forms, fixed biasing and H biasing. The fixed bias design works with a transistor with an appropriate current gain, beta. Temperature changes results in a change of beta. This results in a variation of Ic and consequently, the Q point changes. Hence, the fixed biased arrangement is thermally unstable. In the H biased design, the Q points are independent of beta and therefore the Q points are more stable. Two resistors form a potential divider and fix the base potential. Since the base potential is kept nearly constant, if Ic changes, an increase potential drop would develop across RE and VBE would decrease. This results in Ic dropping to its original value. This biased arrangement is therefore thermally stable. Due to this thermal stability, the H biased arrangement was chosen in preference to the fixed biased arrangement. Now, though the H biasing arrangement was chosen, the type of configuration was still undecided. Three types of configurations exist. These include the common emitter, common base and common collector. According to Kuhn 2008, in general, the best amplifier to use is the one whose input resistance is comparable to the source resistance and whose output resistance is comparable to the load resistance. Source Resistance/ Load resistance Good Choice of Amplifier to consider Greater than 10 Common Collector 2 -10 Common Collector or Common Emitter 0.5 -2 Common Emitter 0.1 -0.5 Common Emitter or Common Base Less than 0.1 Common Base Table Showing Choice of Amplifier based on Source/Load Resistance Source: http://www.kennethkuhn.com/students/ee351/text/bjt_general_design.pd, accessed 17th November 2010 at 5:17 pm. It can be shown that the common-emitter amplifier is capable of achieving the highest possible power gain. He concludes by saying that, overall, the common-emitter amplifier is the most flexible in terms of input and output resistance while also achieving reasonable power gain. Therefore, the common emitter configuration was chosen. Figure 7 shows this configuration. Figure 7: Common Emitter Configuration Source: Electronic Workbench Software- Multisim Figure 7: Common Emitter ConfigurationQ1 2N3904 Vcc R1 R2 Re RE* Rc RL Co Ci CE This design project would serve as an introduction to the practical application of electronics. With the experience, knowledge and understanding gained in designing and the building the circuit, more advanced and complex circuits could possibly be built. These circuits would then be used in everyday applications, e,g a microphone, speaker or perhaps a new innovation. This simple circuit in itself could be used to amplify signals with the appropriate adjustments. Design Objectives The following shows the specifications required for the design of the amplifier. The specifications involved in the design of the single stage H-biased amplifier were as follows: Voltage gain of 50 Lower cut off frequency less than 100Hz Maximum symmetrical swing Supply voltage of 15volts It was required that a small signal NPN 2N3904 transistor be used in the design. A fixed load resistance of 100kà ¢Ã¢â‚¬Å¾Ã‚ ¦ was also required. Method The following shows the apparatus and materials used in the design project, the operating conditions, how the various resistor and capacitor values were obtained and the basic laboratory procedure. Apparatus and Materials The following shows a list of the apparatus and materials used in overall design and building of the amplifier. 2N3904 NPN Transistor Solder less Bread board Resistors (56à ¢Ã¢â‚¬Å¾Ã‚ ¦, 680à ¢Ã¢â‚¬Å¾Ã‚ ¦, 3.6kà ¢Ã¢â‚¬Å¾Ã‚ ¦, 62kà ¢Ã¢â‚¬Å¾Ã‚ ¦,10kà ¢Ã¢â‚¬Å¾Ã‚ ¦,100kà ¢Ã¢â‚¬Å¾Ã‚ ¦) Capacitors (4.7uF, 47uF ,330uF) Connecting wires Pliers Dual trace Oscilloscope Power Supply Function Generator Multi-meter LRC meter Analysis of Operating Conditions The following gives an analysis of the operating conditions for the circuit. The design of the amplifier consisted of two types of operating conditions. These included the DC conditions and the AC conditions. The DC and AC conditions were not mixed. Therefore each type of operating condition was considered individually. DC Analysis The following describes the operating conditions for the DC analysis. In DC circuits, capacitors act as an open circuit. In an open circuit, no current flows. Therefore the capacitors were omitted when considering the operating conditions for DC. For the transistor to function as an amplifier, the various quiescent currents and voltages associated with it need to be known. Also, the resistor values need to be known. Therefore, some calculations must first be made. The figure below shows the circuit required for DC analysis. Figure : Circuit Required for DC Analysis Figure : Circuit Required for DC AnalysisVcc R2 RE Rc Q1 2N3904 R1 Figure 8: Circuit Required for DC Analysis Source: Electronic Workbench Software Multisim Note that this circuit is similar to figure 7. However, the capacitors were omitted as they are part of the AC analysis. The supply voltage, , was given as 15 volts. Determining Ic The following describes how the value of Ic , was chosen. The transistor datasheet (found in the appendix) was used to choose an appropriate value for. Firstly, the graph of Typical Pulsed Current Gain vs Collector Current, , was used. Since the quiescent points are independent of beta, ÃŽÂ ², (), then the exact value of ÃŽÂ ² becomes irrelevant. Hence, beta can be chosen as any appropriate value. Since the operating temperature for the transistor was room temperature, therefore, the graph at 25 °C was selected. From the graph it was seen that beta was relatively constant at an of 2mA. Due to this constant beta, a selection of 2mA for was made. It was found that beta was approximately 230. It should be noted that a value of 1mA could also have been chosen, based on the same criteria upon which was chosen. To add some justification to the value chosen, the graph of Base- Emitter ON voltage vs Collector Current was also considered. It was known that an approximate value for was 0.68V. Using again the graph at room temperature, (25 °C), the corresponding value for a voltage of 0.68 was 2mA. Since multiple graphs indicated that a value of 2mA would be appropriate, therefore, was chosen to be 2mA. Calculation of The following shows the steps involved in determining the value of. A requirement was maximum symmetrical swing. That is, must be able to increase and decrease by the same value. From the circuit,( figure 8), is in series with the emitter of transistor, and therefore in series with the voltage. Since would cause a voltage drop, , across itself, this would therefore reduce the voltage . This voltage drop across, that is, would therefore limit the symmetrical swing. So, to obtain maximum symmetrical swing, it was desired that be negligible, when compared to the voltage drop across. With a small , then would be large, and hence produce maximum symmetrical swing. Since 10% can be considered negligible in comparison to 90%, it was therefore assumed that was one tenth the supply voltage. That is,= 1/10..[1] Since was given as 15volts, then, = 1/10 (15) = 1.5 volts Ohms law was applied, Then, = à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦ [2] In the circuit, the current which flows through , was the same current . (It is seen later that à ¢Ã¢â€š ¬Ã‚ ¦.[20]) Therefore, = à ¢Ã¢â€š ¬Ã‚ ¦[3] The formula was rearranged to make the subject, =à ·. Since = 2mA, Therefore,= 1.5Và ·2mA So, = 750à ¢Ã¢â‚¬Å¾Ã‚ ¦ Calculation for The following shows the steps involved in determining the value of. The design for maximum symmetrical swing was considered here. Applying Kirchhoffs Voltage Law (K.V.L) to the circuit: = à ¢Ã¢â€š ¬Ã‚ ¦..[4] Equation [4] was rearranged giving the equation: = So, = -à ¢Ã¢â€š ¬Ã‚ ¦..[5] Recall, for maximum symmetrical swing, that must increase and decrease by the same value. This implies that would therefore be equal to. à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[6] Therefore, = -à ¢Ã¢â€š ¬Ã‚ ¦..[7] So, 2=-à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[8] Hence, =-) à ·2 à ¢Ã¢â€š ¬Ã‚ ¦.[9] Where =15V and =1.5V Therefore = (15-1.5) à ·2 =13.5 à ·2 = 6.75V Ohms law was applied, = à ¢Ã¢â€š ¬Ã‚ ¦[10] The formula was rearranged to make the subject giving, = à ·, Since = 2mA Therefore, = (6.75V) à · 2mA = 3375à ¢Ã¢â‚¬Å¾Ã‚ ¦ Calculation for values of and The following shows the steps involved in determining the value of and . The circuit in figure 8 was firstly redrawn as shown in figure 9. This was done so that the Thevenins model of the circuit could be easily obtained. Figure 10 shows the Thevenins model for the circuit. Q1 2N3904 Vcc R1 R2 RE Rc Vcc Figure : Redrawn Circuit from Figure 8 Source: Electronic Workbench Software- Multisim Q1 2N3904 Vcc RTH Re Rc VTH Figure 10: Thevenins Model of the Circuit Source: Electronic Workbench Software From figure 9, Thevenins Theorem was applied for the resistance. This gave, = // à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[11] = ) à · à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦.[12] Below shows how an expression for was found. Since was in parallel with, therefore, the voltage across is the same as the voltage across. Voltage Divider Rule was applied to obtain: = à · ]* à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦.[13] K.V.L was applied to the circuit in figure 10, this resulted in, = ++à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦.[14] But = +à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦.[15] So, by substitution of equation [4] into equation [3] gives, = +++à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[16] Also, = ÃŽÂ ²Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[17] Substituting [17] in [16] gives, = ++ (ÃŽÂ ²+ = ++ (1+ÃŽÂ ² = + {1+ÃŽÂ ²)+ à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦..[18] Rearranging [18] to make the subject of the formula gives, +{1+ÃŽÂ ²)+ = +{1+ÃŽÂ ²) =- Therefore, =- à · +{1+ÃŽÂ ²)à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[19] Since hfe is high, to ensure that IB does not cause variations in VB, IB was chosen as one tenth . Also, Recall [15]:= + In transistor designs, the base current, , is made much smaller than the collector current. (recall from introduction). Hence, à ¢Ã¢â€š ¬Ã‚ ¦.[20] Since is therefore significantly smaller than, then, it can be said that is negligible when compared to. Therefore, it was assumed that was one tenth of. So =1/10 à ¢Ã¢â€š ¬Ã‚ ¦[21] Since = 2mA Hence,=1/10 (2mA) So,= 0.2mA Since = I2, then, I2 = 0.2mA When the transistor is on, also known as being forward biased, there is a voltage drop of 0.7 volts across the base-emitter.i.e. = 0.7 volts. K.V.L was applied to the circuit in figure, V2=+à ¢Ã¢â€š ¬Ã‚ ¦[22] Ohms law was used, I2R2= +à ¢Ã¢â€š ¬Ã‚ ¦.[23] The formula was rearranged to make R2 the subject, R2 =+) à · I2 à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[24] Since = 1.5V, = 0.7V and I2 = 0.2mA Then, I2R2= (1.5V +0.7V) Therefore, R2 = (1.5V +0.7V) à · 0.2mA R2 = 2.2V à · 0.2 mA Hence, R2 = 11kà ¢Ã¢â‚¬Å¾Ã‚ ¦ The Voltage divider rule was used to find the value of R1 So, VB =(R2 * ) à · (R1 +R2)à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[25] The formula was rearranged to make R1 the subject. (R1 +R2) VB = (R2 * ) (R1 +R2) = (R2 * ) à · VB Therefore, R1 = [(R2 * ) à · VB ] R2 à ¢Ã¢â€š ¬Ã‚ ¦..[26] So, R1= [(11kà ¢Ã¢â‚¬Å¾Ã‚ ¦ *15V)à · 2.2V] 11kà ¢Ã¢â‚¬Å¾Ã‚ ¦ R1= [(165000)à · 2.2] 11kà ¢Ã¢â‚¬Å¾Ã‚ ¦ R1= 75000-11000 Therefore, R1 =64000à ¢Ã¢â‚¬Å¾Ã‚ ¦ R1 = 64kà ¢Ã¢â‚¬Å¾Ã‚ ¦ The following table shows the calculated and standard resistor values. The standard resistor values represent the resistors that are available. It is unlikely that stores have a 3.375kà ¢Ã¢â‚¬Å¾Ã‚ ¦ resistor, hence a value close to it (3.6kà ¢Ã¢â‚¬Å¾Ã‚ ¦) would be chosen. Resistor Calculated Value (kà ¢Ã¢â‚¬Å¾Ã‚ ¦) Standard Value(kà ¢Ã¢â‚¬Å¾Ã‚ ¦) RE 0.75 0.75 RC 3.375 3.6 R1 64 62 R2 11 10 Table Showing Calculated and Standard Resistor values Now that R1 and R2 have been calculated, VTH , RTH and IB , can now be calculated. Recall [12] = ) à · à ¢Ã¢â€š ¬Ã‚ ¦[12] Therefore, RTH = (64k*11k) à · (64k+11k) RTH = 9386.667à ¢Ã¢â‚¬Å¾Ã‚ ¦ Recall [13] = à · ]* à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[13] Therefore, = [ 11k à ·(11k +64k)]* 15 = 2.2V Therefore, IB can now be found. Recall [19] =- à · +{1+ÃŽÂ ²Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[19] So, IB = 2.2 -0.7 à · (9386.667 + {1+230}(750) IB = 0.0082mA AC Analysis The following describes the operating conditions for the AC analysis. The AC analysis was done using h-parameters. The figure below shows the circuit used for AC analysis. Q1 2N3904 Vcc R1 R2 Re RE* Rc RL Co Ci CE Figure : Circuit used for AC Analysis Source: Electronic Workbench Software- Multisim The equivalent of this circuit is shown below. Figure 12: Equivalent Circuit Source: Electronic Workbench Software-Multisim Figure : Equivalent Circuit hfeIB R1 hie R2 Re Rc RL K.V.L was applied and the result was obtained. (Re and RE* were taken as a single resistor, RE) So, Vin= hie IBà ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦.[27] And Vo= hfeIB(Rc//RL)à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[28] Since voltage gain is given by, Av = à ¢Ã¢â€š ¬Ã‚ ¦.[29] Therefore, Av = -hfeIB(Rc//RL) à · hie IBà ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦.[30] Hence, Av =- hfe(Rc//RL) à · hieà ¢Ã¢â€š ¬Ã‚ ¦..[31] The value for Av was therefore found. In the transistor data sheet, using the graph of Input Impedance, it was seen that at a collector current, of 2mA, that the corresponding hie value was 2kà ¢Ã¢â‚¬Å¾Ã‚ ¦. The graph of Typical Pulsed Current Gain vs , hfe was 230. Av = 230( 3375//100000) à · 2000 Av = -230 ( 3265) à · 2000 Av = -(750950) à · 2000 Therefore, Av = 375.475 However, the design specified a voltage gain of 50. Since 375.475 is greater than 50, the resistor RE was split into two smaller resistors, Re and RE*. The resistor RE* was bypassed with a capacitor. (Page 28 shows theoretically how the introduction of the bypass capacitor reduces the gain of the amplifier.) Calculation of Re and RE* The following shows the method in which Re and RE* were determined K.V.L was applied to the circuit in figure 12. At the input, Vin = IBhie + (IB +hfeIB) Reà ¢Ã¢â€š ¬Ã‚ ¦[32] Vin = IB (hie + (1 +hfe) Re )à ¢Ã¢â€š ¬Ã‚ ¦[33] At the output, Vo = -IBhfe (Rc //RL)à ¢Ã¢â€š ¬Ã‚ ¦..[34] Therefore, voltage gain, Av = Voà · Vinà ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦ [29] Av = -IBhfe(Rc //RL) à · [IB(hie + (1 +hfe) Re )]à ¢Ã¢â€š ¬Ã‚ ¦[35] [35] Simplified was to, Av = hfe(Rc //RL) à · [(hie + (1 +hfe) Re )]à ¢Ã¢â€š ¬Ã‚ ¦..[36] The formula,[36] was rearranged to make Re the subject. So, [(hie + (1 +hfe) Re )] = hfe(Rc //RL) à · Av [(1 +hfe) Re ] = [ hfe(Rc //RL) à · Av ] hie Therefore , Re = {[ hfe(Rc //RL) à · Av ] hie }à · (1+ hfe )à ¢Ã¢â€š ¬Ã‚ ¦[37] The appropriate values were substituted into the equation and the value of Re was determined. Since the desired gain is 50, hence, Av is substituted as 50. Re = {[ 230(3375 //100) à · -50 ] 2000 }à · (1+ 230) Re = {[ 230(3265) à · -50 ] 2000 }à · ( 231) Re = {[ 15019 ] 2000 }à · ( 231) Re = {13019}à · ( 231) Re = 56.359 Therefore, Re = 56à ¢Ã¢â‚¬Å¾Ã‚ ¦ Since RE = Re + RE*à ¢Ã¢â€š ¬Ã‚ ¦..[38] Then , 750 = 56 + RE* Therefore, RE* = 694à ¢Ã¢â‚¬Å¾Ã‚ ¦ The following table shows the calculated and standard resistor values for Re and RE*. The standard values represent the values of resistors that were available. Resistor Calculated value (kà ¢Ã¢â‚¬Å¾Ã‚ ¦) Standard value (kà ¢Ã¢â‚¬Å¾Ã‚ ¦) Re 0.056359 0.056 RE* 0.694 0.680 Table Showing Calculated standard resistor value Calculation for Capacitor values, Ci ,Co and CE The following shows the steps involved in the calculations of Ci , CO and CE. Ci and CO act as decoupling capacitors in the circuit. The power supply decoupling capacitors filter undesired electronic signals which have been coupled onto the power supply voltage. (Kelly and Emad 1998). Essentially, what this means is that the decoupling capacitors block the DC voltage while permitting the AC to flow. This prevents the DC signal from affecting the bias. Also, it blocks the DC from reaching the AC input source. The main function of the bypass capacitor was to reduce the gain of the amplifier to the desired value. Without the bypass capacitor, the gain of the amplifier was given by, Av =- hfe(Rc//RL) à · hieà ¢Ã¢â€š ¬Ã‚ ¦..[31] With the introduction of the bypass capacitor, the gain was now denoted by, Av = hfe(Rc //RL) à · [(hie + (1 +hfe) Re )]à ¢Ã¢â€š ¬Ã‚ ¦[36] From these two equations, since the numerator is the same, and the denominator is larger in [36], hence, the value of Av would be smaller. Therefore, the gain would be reduced with the introduction of the bypass capacitor. Also, the bypass capacitor is to filter out noise at high frequencies. Basically, as the frequency of a signal increases and the pulse width decreases, the impedance of the capacitor decreases and the bypass capacitor acts as a short circuit to these high frequency charges. The dissipation of high frequency charge is related to the value of the capacitor and the subsequent series resistance associated with it. (Wenzel et al.1997.) Firstly, when a particular capacitor was being analyzed, (to be calculated), the other two capacitors were considered as short circuits. This was done so that the effect of the individual capacitor on the circuit could be analyzed. Capacitors act as short circuits, allowing current to flow through them and bypassing the component. The reactance of a capacitor, Xc, is given by, Xc =1à · (2à Ã¢â€š ¬fC)à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦.à ¢Ã¢â€š ¬Ã‚ ¦[39] where f is the frequency. There would be a voltage drop across the capacitor. With respect to the capacitor at the input, this voltage drop across the capacitor would therefore limit the voltage across the resistors R1 and R2 .Hence , reduce the voltage being sent to the input of the amplifier to be amplified. It is desired that the maximum voltage possible, be sent to the input to be amplified. Since this voltage drop across the capacitor limits the voltage being sent to the input, it is therefore desired that the voltage drop across the capacitor be negligible in comparison to the input impedance of the circuit. Hence, the reactance of the capacitor was assumed to be one tenth of the input impedance, Zi. So, for capacitor Ci, , Reactance Xci = 1/10 Zià ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦[40] In figure 12 , the input impedance Zi is given by, Zi = R1 //R2//hieà ¢Ã¢â€š ¬Ã‚ ¦..[41] In the transistor data sheet, using the graph of Input Impedance, it was seen that at a collector current, of 2mA, that the corresponding hie value was 2kà ¢Ã¢â‚¬Å¾Ã‚ ¦. Therefore, Zi = 64kà ¢Ã¢â‚¬Å¾Ã‚ ¦//11kà ¢Ã¢â‚¬Å¾Ã‚ ¦//2kà ¢Ã¢â‚¬Å¾Ã‚ ¦ Zi =9.387kà ¢Ã¢â‚¬Å¾Ã‚ ¦//2kà ¢Ã¢â‚¬Å¾Ã‚ ¦ So, Zi = 1.649kà ¢Ã¢â‚¬Å¾Ã‚ ¦ Now, Xci = 1/10 Zi Hence, Xci = 1/10(1.649kà ¢Ã¢â‚¬Å¾Ã‚ ¦) So, Xci = 164.9à ¢Ã¢â‚¬Å¾Ã‚ ¦ Recall [39], Xc =1à · (2à Ã¢â€š ¬fC) Therefore, Xci =1à · (2à Ã¢â€š ¬fCi) The formula was rearranged to make Ci the subject. 2à Ã¢â€š ¬fCi =1à · Xci Therefore, Ci = 1à · (Xci *2à Ã¢â€š ¬f)à ¢Ã¢â€š ¬Ã‚ ¦.[41] Since f represents the lower cut off frequency, which was given as 100Hz. Hence the value for Ci was found. C i= 1à · (Xci *2à Ã¢â€š ¬f) Ci = 1à · (164.9 *2à Ã¢â€š ¬{100}) Ci = 1à · (103609.726) Ci = 0.00000965F So, Ci = 9.65uF A similar method was used to find CO. The reactance of the capacitor was considered negligible in comparison the output impedance. This was done so that there would be a minimal voltage drop across the capacitor and the maximum output voltage dropped across the load resistor, RL. So, XCO = 1/10 ZO, (similar to [40] ) Where ZO= (RC//RL) Then, ZO= (3.375kà ¢Ã¢â‚¬Å¾Ã‚ ¦//100kà ¢Ã¢â‚¬Å¾Ã‚ ¦) So ZO= 3.265kà ¢Ã¢â‚¬Å¾Ã‚ ¦ Since XCO = 1/10 ZO Then, XCO = 1/10(3.265kà ¢Ã¢â‚¬Å¾Ã‚ ¦ XCO =326.5à ¢Ã¢â‚¬Å¾Ã‚ ¦ Now, XCO =1à ·(2à Ã¢â€š ¬fCO) The formula was rearranged to make CO the subject. The result was as follows. CO = 1à · (XCO *2à Ã¢â€š ¬f) Therefore CO =1à ·(326.5 *2à Ã¢â€š ¬*100) CO = 4.87uF Similarly, for CE. The reactance of the capacitor was considered negligible in comparison the output impedance. This was done so that there would be a minimal voltage drop across the capacitor and the maximum output voltage dropped across the resistor, Re. XCE = 1/10 Re XCE = 1/10 (56) XCE = 5.6à ¢Ã¢â‚¬Å¾Ã‚ ¦ Since , XCE = 1à · (2à Ã¢â€š ¬fCE) The formula was rearranged to make CE the subject. The result was as follows. CE= 1à · (XCE*2à Ã¢â€š ¬f) CE = 1à · (5.6*2à Ã¢â€š ¬*100) CE = 284uF The following table shows the calculated, standard and the chosen capacitor values for Ci ,Co and Ce . Capacitor Calculated Value (uF) Standard Capacitor Value(uF) Capacitor value chosen (uF) Ci 9.65 10 ,47 47 Co 4.87 4.7 4.7 Ce 284 330 330 Table Showing Calculated and Standard Capacitor values The standard capacitor values represent the capacitor values that were available in stores. It is generally rare to find a capacitor value of exactly 4.87uF, hence a value of 4.7uF was chosen. The value of Ci was chosen to be 47uF instead of 10uf to ensure that the frequency was not exceeded. From the equation, C i= 1à · (Xci *2à Ã¢â€š ¬f), it was noticed that if that capacitor value was increased, the frequency would decrea

The Language of the Mafia Essay -- Exploratory Essays Research Papers

The Language of the Mafia Mobspeak is a language that grows out of secrecy, and who can be more secret than the Mafia? The anti-social nature of the Mob is the perfect breeding ground for an "Antilanguage," which is, according to M. A. K. Halliday, a language that develops out of an antisociety which stands as a mode of resistance' to the society within which it exists (Butler 1). In his 1976 article, Halliday suggests that in these societies, a type of language forms in an effort to exclude outsiders for various reasons. One striking reason for the existence of an antilanguage is to hide the activities of the group. Halliday gives evidence for this claim through the existence of Elizabethan thieves cant, a form of communication derived in the Calcuttan underworld that thieves use to speak to one another without fear of incriminating themselves. Similarly, the Mafia -- which is often the target of FBI wire-taps -- requires its own thieves cant. The Mob constantly tries to hide its activities from the authorit ies. One way to accomplish this goal is to use somewhat cryptic vocabulary. For instance, there are over twenty words for the verb to kill'. If someone were to disrespect The Family' somebody might do a piece of work on' him. He could get whacked, erased, burned, clipped, iced, or hit -- just to name a few. In order to have a full understanding of the Mafia's unique use of language it is necessary to realize the context in which it is used. The Mafia's major business is providing "protection" for merchants in their territory. Basically, they insure that no other criminals will give any of their clients trouble. However, when anything comes under mob protection, the Mafia considers itself its "owner". They do not offer... ...English. Virtually everything the Mafia does has an impact on its language. Many defining characteristics of Mobspeak spawn from the illegal activities of the organization. They speak in codes due to a requisite for secrecy. The same applies in their unreserved overuse of profanity -- another way of expressing power. Their linguistic characteristics are a reflection of their roguish behavior and lifestyle. Overall, the language of the mafia is unique in that employs Halliday's ideas of an antilanguage in a modern sense. Sources Cited Butler, Todd. Exploring the Antilanguage of Gangster Rap. The Secol Review V. 19 (Spring 1995): 1-24 Le Vien, Douglas, Jr. and Juliet Papa. The Mafia Handbook. New York: Penguin Books, 1993 Pieggi, Nicholas. Wiseguy. New York: Simon and Schuster, 1986 Pieggi, Nicholas. Casino. New York: Simon and Schuster, 1995

Losing Weight Expository Essay

Losing Weight COM/150 Effective Essay Writing (AXIA) Struggling with the issues of weight loss and living a healthier lifestyle. Losing weight could be a short term goal, but the main idea is to eat and maintain a healthier lifestyle. Many Americans struggle with difficulties of weight loss, not only losing the weight but keeping it off. Different methods are used for losing weight, such as, exercise, various types of dieting and some medically needed procedures. Even though weight loss is vital to many people’s careers and futures, it doesn’t mean that it’s easier for these people than it is for you and me. The difference is that most people have a state of mind that they can’t afford to fail. So they are willing to pay thousands of dollars for personal coaching and expensive surgical procedures to lose the weight and keep it off. On a long-term basis, there is only one safe, effective, foolproof way to get down to a lower weight and keep off the extra pounds. That is eating a healthier reduced-calorie diet and getting enough exercise on a daily basis. Many have come to think that eating fewer calories means eating less food. However, it doesn’t mean that you have to walk around in a state of deprivation. A feeling of deprivation is the surest way to make your weight-loss plan fail. Most people find themselves eating more food when they deprive themselves. Most first-time dieters don’t enjoy counting calories because they quickly discover that it is time consuming and can become a complicated chore. Calorie counting goes hand in hand with feeling deprived that sometimes causes a person to back away from their diet. Struggling with weight-loss can be a very serious issue. The quality of your life and how long you live is to a great extent in your own hands. For what you choose to eat largely determines whether your body wards off or becomes vulnerable to a host of life-shortening diseases, such as diabetes, cancer, stroke, hypertension, and heart disease. But changing to healthy eating habits, especially if you have not previously followed the guidelines recommended by nutritionists, can be a challenge. One could have a normal number of calories but have them all from fat, and cause other problems that can lead to heart disease or stroke. Having a similarly unbalanced diet with all the calories coming from carbohydrates can lead to insulin resistance and diabetes, plus it's a really easy way to gain weight as you get older. It also promotes dental problems, especially if it's foods that tend to get caught in your mouth or on your teeth. The easiest way to do that is to avoid or at least severely limit intake of fast foods, candies, snack foods, and sweet desserts. There are all kinds of health issues related to over consumption of sugar. Diabetes would be the number one health concern. But, diabetes is not the only ill effect from over consumption of sugar. Obesity, thyroid dysfunction, kidney malfunction, and intestinal problems can all be directly associated with too much sugar consumption. Once your body has reached the point of unhealthy functioning, or you have placed such a strain on your body from over consumption that one of the related diseases has taken hold, it's almost impossible to correct one problem without creating another. Once you have become a diabetic, there are so many complications; simply choosing dieting and exercise is no longer an option. The health concerns you now have far outweigh the easy solution of diet and exercise. However, high blood pressure is also a known risk factor, for those that are over weight and have lack of physical activity and does not maintain healthy eating habits. The more you weigh the more blood your body needs to supply oxygen and nutrients. As the volume of blood circulated through your blood vessels increases, so does the pressure on your arteries. People who are inactive tend to have higher heart rates. The higher your heart rate, the harder your heart must work with each contraction and the stronger the force on your arteries. Lack of physical activity also increases the risk of being overweight with stress that can lead to temporary high blood pressure. If you try to relax by eating more you may only increase the risk of having hypertension. How to be successful with weight loss for a healthier lifestyle most people start by eating the right foods that can help us avoid certain diseases or recover faster when illnesses occur. These and other important functions are fueled by chemical substances in our food called nutrients. Nutrients are classified as carbohydrates, proteins, fats, vitamins, minerals, and water. Although humans need food to survive, many people eat too much, or choose the wrong foods to eat, which leads to the body putting on weight. When you eat more calories than your daily energy requirements the extra calories are stockpiled as body-fat. Slowly these fat cells keep building up and settle on the hips, waist, thighs, upper arms and back, as well as around the heart, kidneys, liver and other organs. Fortunately body-fat can easily convert into energy; however, you must reduce your fat intake and exercise regularly. If you only reduce your fat and don't exercise, your body will also break down muscle tissue and use them for fuel. Many people struggle to lose weight that is put on and that's where weight loss companies come to the rescue. There are many different ways for weight to be lost, as there are many different sorts of weight loss companies. Firstly there is exercise centers such as gyms and recreation centers which focus on fitness as the key to lose weight, Many varieties of pills, tablets and vitamin supplements are available that claim to make you lose weight. Meal replacement programs are available where the consumer has a liquid drink instead of a meal and this provides them with necessary nutrients. Diet plans are commonly found in magazines as well as the more common weight loss centers which some supply you with foods to eat and others inform you and assist you in making wise food choices. In conclusion, I found in order to be successful with losing weight for a healthier lifestyle you can follow techniques such as, eating more vegetables during meals as water-rich foods like zucchini, tomatoes, and cucumbers reduce your overall calorie consumption. Some other water-rich foods include soups and salads; they are good source of nutrition, take most of the calories before noon because studies tell that the more you eat in the morning, the less you'll eat in the evening. Moreover, you will get more chances to burn off those early-day calories than late-night calories, make water your favorite drink. A person must have a minimum of 8 glasses of water in a day. Avoid taking soft drinks or carbonated beverages; moreover replace them with water. Water helps in reducing weight in the most effective manner. Avoid taking white foods as they contain large amounts of carbohydrates, which may further lead to weight gain. Replace white sugar, white rice, and white flour with whole grain breads and brown rice. Eat fruit rather than drinking fruit juice. Eating whole foods will keep you satisfied for longer period of time than juice. Moreover, fruit juices are very high in calories. Use skimmed milk as it is high in calcium and low in calories. For coffee, use nonfat powdered milk. Don't stuff yourself with food in a single sitting; instead have 5 to 6 small meals or snacks in a day. Eating several small meals helps the body to release less insulin, which keeps blood sugar steady and helps to control hunger. More and more methods develop each day but studies show the most effective method is changing your diet mentally and physically challenging yourself. Picture this: The weight is over. Of course, this essay is not promising you that you will add years to your life, or that a funny and fabulous new personality will emerge. Also, it is not promising that you will become thinner than you’ve ever been when changing your eating habits. What it is promising is that a changed relationship with your eating habits will add benefits to your life even as it subtracts pounds and takes away your fear of regaining weight. Knowledge is power, as the saying goes, and the knowledge you gain from this essay can give you the power you need to change the most constant, necessary, and ongoing relationship that you have, your relationship with food. The knowledge you take from this essay should give you a realistic sense of just what is an appropriate goal for you. Genetic predisposition and even psychological factors can affect your weight. Therefore, for the person you are, there’s an appropriate weight at which you’ll look and feel your best. That’s the goal you want to aim for and maintain. References {text:bibliography-mark} (http://exercise. about. com/cs/weightloss/a/howtoloseweight) (http://acefitness. org/blog/494/how-can-i-lose-weight-and-keep-it-off)

Female Teachers Arrested for Having Sex With Students

Who Killed JFK Essay - 1699 Words

Review of Research The assassination of John F. Kennedy is said to be, as from the Warren report, a murder. The Warren report states that a man, Lee Harvey Oswald, fired 3 shots from the 6th floor of the Texas Book State Depository building. One missed the President’s motorcade completely; another hit President Kennedy in the neck, and the last hit him in the head, which was later said after an autopsy, to be the cause of death. The problem with the Warren report is that some eyewitnesses say that shots came from in front of the motorcade, which would mean there were two or more shooters. The FBI did little to help the Warren Commission in finding answers; initially the report was to remain sealed for 75 years or until the year†¦show more content†¦Oswald himself also had what appears to be curious ties to Cuba and Fidel Castro. In the months just prior to the Presidents assassination, Oswald was arrested in New Orleans for disturbing the peace while he was handing out pro-Castro leaf lets. While in jail he was interviewed by the FBI as his own request. The U.S. Military has also been an easy target. By sworn testimony from Robert McNamara, the Secretary of Defense at the time; in October of 1963, approximately one month before his death, President Kennedy, signed an order authorizing the pull out of 1,000 troops from Vietnam by the end of 1963. This decision was unpopular to many and was reversed by President Johnson when he took the oath of office after the Presidents untimely death. Jack Ruby, a nightclub owner in Dallas, murdered Lee Harvey Oswald as Oswald was being transferred to the county jail. Although Ruby has never been linked conclusively to the mafia, it is possible that the nature of his business required him to cross paths with underworld criminals. Ruby may have been told by a high ranking person in the mafia to kill Oswald so he couldn’t tell anything to the police. Multiple Shooters There are many different views and ideas supporting the multiple shooter theory. Some say that the shots had to come from the front because Kennedy’s head goes back and to the left. Also, they say thatShow MoreRelatedWho Killed Jfk? The Kennedy Conspiracy?1047 Words   |  5 PagesKevin Myers Professor Vollaro ENC 1101 June 8, 2016 Reader Response Essay â€Å"Who Killed JFK? The Kennedy Conspiracy† In The Week’s article, â€Å"the CIA, aliens and the Illuminati, those shots are continuing to reverberate across the US.† I believe the John F. Kennedy’s assassination was an inside job, the only problem is they’re so many variables, and so much controversy in that particular fragment of history; Politics, The Mafia, The Soviet Union, Possibly the CIA, our own government could all haveRead MoreThe Assassination of John F. Kennedy Essay916 Words   |  4 PagesF Kennedy was shot by Lee Harvey Oswald. He became the second out of the two most remembered presidents to be killed, the first being Lincoln. However, most people believe that John Wilkes Booth killed Lincoln, but most people don’t think Oswald killed JFK. Ranging from his future-self killing his past self to other crazy theories like aliens, but 55% of our nation still think that JFK was involved by some government conspiracy at the time of his death. Right now in 2014 America some people stillRead MoreJfk Was A Victim Of A Conspiracy Essay1067 Words   |  5 Pagespeople gathered in downtown Dallas, Texas to see President John F. Kennedy ride through a parade. Many spectators watched as President JFK was shot. Since JFK’s death, 50 years ago, many conspiracy theories have evolved. 73% of all Americans believe that JFK was a victim of a conspiracy (Southwell). The Warren Commission concluded that Lee Harvey Oswald killed John F. Kennedy, and that he acted alone. However, over half of the American population believe otherwise. Through the years there haveRead MoreThe Assassination Of Jfk Assassination Theory1385 Words   |  6 Pagesessay is the JFK assassination theory. I would like to research this because I have seen documents and videos online and on television about the conspiracy but I have not done full research into it to see the facts. With the presidents of the United States they are able to make or break the country with their decisions, with that JFK was assassinated due to that and other reasons. I will be going into this research thinking that there is a conspiracy behind the assassination of JFK that it wasn tRead MoreJfk And The President Jfk1368 Words   |  6 PagesJohn Fitzgerald Kennedy (JFK) was assassinated in Dallas Texas. The nation and the whole world was shocked in that day. In fact, president JFK was preparing for his next combine in Texas, he took a road trip by a motorcade with his wife Jacqueline Kennedy, Governor John Connally, and his wife Nellie. The road trip went through Dealey Plaza in downtown Dallas towards the trade mart, where the president was scheduled to give a speech there. The road that the president JFK was traveling on by his motorcadeRead MoreAssassination Of The Post War 20th Century1292 Words   |  6 Pagescircumstances, together with the fact his assassin was himself murdered two days later, have led to a host of conspiracy theories over who was to blame.In 1964, the Warren Commission concluded Kennedy was killed by a lone assassin – Oswald – while three other investigations, in 1968, 1975, and 1978-79, confirmed the commission s conclusion that JFK had been killed by two shots from behind.However, the 1978-79 House select committee on assassinations decided there was a high probability that a secondRead MoreThe Assassination of Kennedy and The Cons piracies Surrounding It1530 Words   |  7 Pagespresident January of 1961. The people of America adored him and his wife, Jacqueline. However, on November 22, 1963, Kennedy was shot and killed while riding in the back of his car through Dallas, Texas. The audience of the parade he was in had to watch in horror as their idol died in front of them. He was 46 years old. We grew being told in school that the man who shot John F. Kennedy was Lee Harvey Oswald. However, as I grew older I started learning more and more outside of school about the Read MoreMystery of Who Killed John F Kennedy1483 Words   |  6 Pagescountry and the world. JFKs assassination was the first for an American President in modern times. According to the article, Latest JFK Theories, To study the assassination of John F. Kennedy is to study American history, politics, organizing crime, government, and much more (latest JFK Theories 1). An understanding has come clear that four shots were fired at JFK, including three from behind, and one from the right/front of the Presidents limousine. An attempt is and has been made to assembleRead MoreNoah Cooper. Mrs. Sites. English 10A. 15 April 2017. Lee1749 Words   |  7 Pagessatisfied that Oswald was the assassin; that he did not have confederates who are still at large; and that evidence was such that he would have been convicted at trial. Unfortunately the facts on Oswald seem about too pat- too obvious (Marxist, Cuba, Russian wife, etc.) The Dallas police have put out statements on the Communist conspiracy theory and it was they who were in charge when he was shot and thus silenced (â€Å"The JFK Assassination† 2.) The assassination of John F. Kennedy has been a topicRead MoreA Look into the Assassination of JFK981 Words   |  4 PagesJohn Fitzgerald Kennedy was born on May 29th, 1917 in Brooklyn, Massachusetts. He was named after his grandfather, John Francis Fitzgerald, who happened to also have a career in politics as the mayor of Boston, Massachusetts. He had 8 siblings, three brothers and five sisters. His parents were Patrick Joseph Kennedy and Rose Kennedy. His early life in Massachusetts helped shape him into one of the greatest presidents America has ever had. Kennedy was an especially bright young man with many talents

What Is Suffering According To Buddha Example

Essays on What Is Suffering According To Buddha Coursework The Meaning of Suffering in Buddhism The Meaning of Suffering in Buddhism In Buddhist teachings suffering isthe inevitable truth of life. Even though such an approach seems to be pessimistic, it teaches people to be strong when they face suffering in their lives. Suffering is the most common translation of the word â€Å"dukkha† used in Sanskrit. Basically, â€Å"dukkha† means anything temporary in peoples life. The First Nobel Truth of Buddhism says that â€Å"life is dukkha† that is it translated as life is suffering. According to Harvey (2012), â€Å"dukkha† has a wide range of meanings starting from pain up to dissatisfaction. Many processes in human life are â€Å"dukkha† (painful or problematic); death, birth, aging or dissatisfaction are painful but one cannot skip them. Realistic outlook on life is required in Buddhism to look at all these things philosophically. Such states as happiness and joy are also temporary and when they pass they lea d to mental or physical pain. Overall, there is no word in English that renders full meaning of â€Å"dukkha† (Harvey, 2012).The cause of suffering is the fact that people always seek satisfaction outside themselves and they ignore their self. Buddhism teachings state that people can overcome suffering by diligent practice. There Forth Nobel Truth of Buddhism prescribes people to follow the Eightfold Path to Enlightenment by controlling their views, speech, intention, livelihood, action, mindfulness, concentration and effort (Harvey, 2012). Buddhism requires not only believing in the doctrine, but following the exact rules which lead to the desired state of body and mind. As a result, â€Å"dukkha† is not a predetermination for all. Those who follow the right way of life can eliminate suffering and be happy. ReferencesHarvey, P. (2012). An introduction to Buddhism: Teachings, history and practices. Cambridge University Press.

Posttraumatic Stress Disorder By Counselors â€Myasssignmenthelp.Com

Question: Discuss About The Posttraumatic Stress Disorder By Counselors? Answer: Introducation The term refugee signifies persons who have to leave their motherland due to persecution, war and violence. Different working groups comprising of politicians, academicians, aid workers, press and other important individuals or organizations have been working industriously and religiously for the cognitive development and establishment of the socio-political dignity of the so called refugees. Another important thing in this process is migration that is also attached with this topic. The contemporary era has been quite significant in terms of refugee settlement in different countries thus entailing the emergence of global economy and global states comprising of cohesive culture. It has been observed that various countries have different views and conception regarding the refugee acceptance policy. Through this report, an attempt has been made regarding the reasons behind this different conceptions or policies (Kouider, Koglin Petermann, 2014). According to the definition of refugee defined within the framework of the United Nations, the refugees are the people owing to a well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality. They are unable or are unwilling to avail himself of the protection of that country (Neuner et al. 2004)." The simple answer as to why nations should accept refugees would be that most countries over 145 of them are bound by the 1951 Convention that recognizes the status of refugees. However, this answer does not address the in depth issue that is, what political or balance of power would the 145 countries gain by becoming a signatory to a legislation that stipulates that no state parties shall return or expel a refugee in any manner to territories where his freedom and life would be threatened. The refugees are unfortunate foreigners whose life would be jeopardized on the grounds of race, religion, membership or nationality. Then why should nations accept the refugees and be concerned about them. The answer lies deep within the traditions of the Western World. Many people would argue that granting the refugees this right might jeopardize the culture and the standard of living of the citizens of the recipient countries. However, in majority of case, it is exactly the opposite. People usua lly fail to consider the other side of the coin. The refugees belong to distant countries, some of which cannot be pointed out in a map, or countries where they faced war like situation or calamities. When the countries refuse to accept the refugees, it signifies a refusal to a culture that is deep rooted within the western culture. The concept of asylum is profoundly rooted in Western Culture from Antiquity and the Medieval World. The primary reason why the countries should accept the refugees apart from their obligation under the 1951 Convention is the concept of natural right, which states that all men and women are entitled to a given set of rights by virtue of being a human. This doctrine fo natural right is explicitly explained in the beginning of the Declaration of Independence of the United States. It states that all men have been equally created and that their creator has entitled them to certain unalienable rights, among which are the right to pursuit of happiness and right to liberty. Further, the Universal Declaration of Human Rights inspired by the Declaration of Independence has included the essential ideas about the natural rights to the age-old concept of asylum. Article 14 states that everyone has the right to seek and enjoy asylum in other countries from the fear of persecution. The answer to the question why the countries should accept the refugees is because it is a part of the culture of the contemporary era and rejecting to accept the refugees is refusal of the ideas that are permits the society to flourish. The idea that every human being is entitled to pursue his own happiness and this notion is deeply entrenched in the cultural traditions. Hence, if a country rejects the concept of asylum, it amounts to rejection of the culture and humanity. The refugees should be accepted by countries as they already have suffered from the woes of war and it must be a responsibility of the country to abide by their statutory obligation to provide shelter to the refu gees, safeguarding them from being persecution. Humanity is above all and the countries must ensure that the rights of human beings to enjoy liberty and pursuit of happiness. After 1951 Refugee Convention organized by the United Nations, 142 states has signed on the protocol to provide effective shelter to the refugees. There have been several reasons behind the states to accept the refugees and where there have been several countries, which have not focused on the significance of the refugee settlement because of internal economic structure. in his case, Hungary is one of the most important signatories however, several issues have been observed in terms of providing refuge to the number of refugees. Feeble structure of the economic condition and poor political settlement policies has been affecting the refugees in the country. European countries have been effectively extending their borders to provide shelter to them. One of the most important factors is the economic condition and the per capita income of the individual citizen. Since this has been taken into certain consideration pertaining to the effective understanding of the socio political issue, it has been observed that the conflict between the locals and outsiders have become more stringent in terms of accepting the refugees. In this context, this has been taken into certain consideration pertaining to the effective understanding of the fact that in most of the cases there has been continuous fight between these two. According to a report of CNN it has been found that conflict, persecution and poverty have been playing a significant role behind the rejection of the refugees from taking shelter in many of the countries. The Western European countries have been considered as mostly sought after places by the refugees as they provide ample opportunities for them to take shelter. However there are several gateways through which they move towards their targeted places. In this context, this has been taken into certain understanding pertaining to the effective case that was highly effective in terms of creating emergency (Valtonen, 2012). However it can be stated that the problem regarding the refugees has grown tremendously and the countries are forced to change their notions regarding the refugee acceptance. The refugee crisis pushes the European countries towards the mass movement (Easton-Calabria, 2015). It has been observed that the aftermath effect of refugee problem has certain similarity with Second World War. One of the main reasons regarding the overwhelming nature of refugee is the terror caused due to Syria attack. In the recent years, it has been observed that Germany has to spend six billion euros to tackle the refugee rehabilitation program (Karageorge et al., 2017). It is a fact that the countries of the European Union are obliged to accept the refugees due to the Refugee Convention that was conducted after World War II. It has been observed by the United Nations refugee agency that it is the duty of the international community to protect the refugees. The treaty regarding the refugee had been amended in the year 1967 and more than 170 countries are signed to it. The report regarding the refugee accepting policies are shocking. It has been reported that over 360,000 refugees are facing great dilemma due to the brutality of the ISIS and civil wars. Many Gulf countries are denied to accept the refugees as thay are quite near to the provinces of Syria, Iraq and Afghanistan. They are developing the fear for securing the interest of the citizens. Except the security provision, the countries are facing problem regarding the resources and supply of foods due to the refugee problem. In the Schengen area of EU, internal checking becomes a common thing. In the year 2015 to 2016, EU had spent 10 billion Euros behind refugee rehabilitation and this forced to bring a change in the financial policies of the government. Certain proposals have been taken to resettle the refugees in the provinces of Greece and Italy. Different notions have been taken by different countries regarding the refugee system. It has been observed that Germany had spent a lot of money for the resettlement of refugees. Australia has started certain refugee development program. However, the Gulf countries are unable to accept the refugees to their territory due to security issues. The cultural differences are also forced the countries to change their policies. Therefore, it can be concluded that there are certain reasons behind the different responses of the governments of different nations regarding refugee problem. More than 20000 refugees have insecure future in the Gulf countries thus moving towards Northern America and Western Europe. Due to effective geopolitical power game, the countries have been facing several issues pertaining to settlement of those refugees. It can be stated that the United Nations conventions are securing the interest of the refugees but the accepting countries are facing serious problems regarding the financial expenditures and lack of resources. These problems are different in different places and therefore, it has been observed that the policies regarding refugee rehabilitation varied from one state to another. Reference: Easton-Calabria, E. E. (2015). From bottom-up to top-down: The pre-historyof refugee livelihoods assistance from 1919 to 1979. Journal of Refugee Studies, 28(3), 412-436. Jensen, N. 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Treatment of posttraumatic stress disorder by trained lay counselors in an African refugee settlement: a randomized controlled trial.Journal of consulting and clinical psychology,76(4), 686-694. Neuner, F., Schauer, M., Klaschik, C., Karunakara, U., Elbert, T. (2004). A comparison of narrative exposure therapy, supportive counseling, and psychoeducation for treating posttraumatic stress disorder in an african refugee settlement.Journal of consulting and clinical psychology,72(4), 579. Valtonen, M. K. (2012).Social work and migration: Immigrant and refugee settlement and integration. Ashgate Publishing, Ltd..