Designing and Implementing a Precision Rectifier Circuit - Lab Report Example

A LAB REPORT ON DESIGNING AND IMPLEMENTING A PRECISION RECTIFIER CIRCUIT. ……………………………………………………… NUMBER………………………………………………………… INSTRUCTOR……………………………………………………………………… DATE OF SUBMISSION…………………………………………… SIGN………………………………………………………………………… CONTENT OF THE LAB REPORT: Subtopic Page Objectives ……………………………………………………………………………… 3 Abstract ………………………………………………………………………………… 3 Introduction …………………………………………………………………………… 4 Procedures……………………………………………………………………………. 5 Circuit diagrams……………………………………………………………………… 6 Methodology ………………………………………………………………………… 6 Discussion…………………………………………………………………………….. 9 Conclusion……………………………………………………………………………. 9 References……………………………………………………………………………. 11 Section One: Objectives 1. To show an ac current may be converted to a dc current in the process known as rectification. 2. To smoothen the wave produced after rectification by a help of a capacitor. 3. To prove that a diode does not allow back flow of current (no current flows in reversed biasing. Abstract All electrical appliances requires only direct current for their operation , and most electrical power are generated in as alternating current to aid in stepping up voltage hence reducing the power loses during transportation. For the aforementioned reason there is a need to change an alternating current to a direct current. This is achieved through rectification .In this lab report we will determine how a full wave rectification occurs in an alternating current circuit .By a help of a diode which does not allow current to flow backwards, currents are made to flow in one direction hence a direct current is obtained . Introduction A full wave precision rectifier indicates how to produce a direct current by use of four components and some standard diodes. In most cases the ZXTC 1041is used. The circuits are shown for above and below 100mV.This solution is compared with two op-amp precision rectifiers .It converts almost if not all incoming alternating current power to a direct current power .A full wave rectification at times referred to as the heart of the circuit which gives room for the sensors to attach on the RCX in either polarity. Rectification is of many help to us engineers and the society at large, some of the importance of rectification are: it serves in the role of generating direct current which is used as a source of power; Flame rectification is important in detecting the presence of flame. An application such as provision of power to appliances like radio ,television ,laptops ,computer among other always need a constant direct current due to the fact that all electrical appliances requires a direct current for their operation .The output of the rectifier is always connected to a series of capacitors which serves a purpose of smoothening of the waves. Rectification also helps us in detecting of amplitude modulation radio signals. This prevents a very low voltage drop diode and a biased diode with a fixed voltage is used. The devices which promotes this process of rectification is the diode .This type of rectification helps in converting the whole incoming /input waveform to output having a constant polarity which may be a negative or a positive .in the process it converts two polarities of incoming. waveform to pulsating direct current and produces a higher voltage output voltage .the requirement for this rectification are; center tapped transformer or a four diode in abridge arrangement. Section Two: Procedure: 1-Connect the full wave rectifier as shown in the diagram below and have the function generator set to 50Hz and 10 V sinusoidal voltage using the cathode rays oscilloscope . 2. Connect the CRO terminals across resistor terminals. 3. Calculate the Dc level of the full wave rectification using the equation Vdc =V ac= (2Vpeak)/π 4. Take the measurement of the average value and RMS value of the wave across the resistor by help of a digital millimeter. Circuit diagrams: The below diagram shows circuit diagram for a full wave rectification with the output wave before smoothening. Methodology A full wave rectification is composed of a four diode, as seen in the above bridge of a full wave rectification current moves from the current source. Current from the source is first stepped down transformer then transferred to a bridge containing four diode where the rectification occurs. Some currents flows through diode 1 to the diode 2 from point A. Current from point B flows through diode 3 to diode 4 and then combines to the currents from diodes 1 and diode 2 .Even though it is alternating current flowing here there is no current whish flows back from diode 2 to diode 1 and the same applies to current from point B, no current flows from diode 4 to diode 3.The currents from the generation point will be equal to the currents from diode 4 and diode 2 ,this is supported by Kirchhoff’s law of current ( KCL). There is no current flowing directly through the bridge from the junction of diode 1 and diode 3 through the resistor to the junction of diode 2 and diode 4. This is because of reverse biasing which diode 3 provides to the current from B and reverse biasing which diode 1 provides to the current from point A. When the rectified current reaches the targeted point (a point after rectification), there are series of capacitors which helps in the smoothening of waves .This smoothening plays a great as it ensures loses of energy are not such high, smoothening also helps in ensuring that the waves in the radio receiver are very smooth hence continuous sound production without any gaps in the sound produced by the receiver. The solution offered here has an inherent advantage of preventing direct current components in the signal. The voltage here is the amplified by ZXCT1041 which help in producing a unipolar output ,thus it amplifies full wave rectification of the alternating current of the input current and voltage .The diagram below shows a circuit diagram and the smoothen waves after application of a series of capacitors. The average and the root mean square output when there is no load output voltage of an ideal single phase full wave rectifier will be Vdc =V ac= (2Vpeak)/π Section Three: Discussion As seen in above rectification (full wave ) allows all input alternating current to be converted to direct current .The conversion is geared by the presence of semiconductors made called diode which can’t allow backflow of current due because of reverse biasing which creates a large bandgap voltage as electrons are repelled by the negative terminals of the power source and hole also repels the positive terminal .This phenomenon thus makes currents to flow in one direction (direct current ) which is required by all electric appliances. The waveforms in alternating current will have the negative component but after rectification the wave will have only positive part as the direct current moves in only one direction. After connecting the capacitor in the output circuit / output waveform the waves become more smooth which serves many purposes as stated above. Conclusion A precision full wave rectification are always implemented using the ZXCT 1041.This requires the use of two resistors and two capacitors to work effectively .It’s performance is not affected by absolute value .The best match approved for the two resistors as any mismatch is translates to input and output voltages. After the rectification the wave diagrams appears as below: From the diagram it is seen clearly that after rectification there is no component at the negative y-axis. References Jain, A. (2004). Power Electronics and Its Applications. Hong Kong: Penram International Publishing (India) Pvt. Ltd. Lobban, C. S. (1992). Successful Lab Reports: A Manual for Science Students. Carlifonia: Cambridge University Press. Metcalfe, P. (2006). Engineering Studies: Year 11. Norwich: Pascal Press. Paul, B. (2009). Industrial Electronics And Control 2Nd Ed. Tamarind: PHI Learning Pvt. Ltd. Subrahmanyam, V. (2006). Power Electronics: Devices, Converters, Application. Bombay: New Age International (P) Limited. Read More