Low Pass Filters Analysis - Essay Example

Prof. November 14, 2007 Assignment 2 a) Output waveform of a half wave rectifier Without capacitor filtering Sine wave, Amplitude = Vs - Vd X-axis-Voltage, Y-axis---Time With capcitor filtering b) Full wave Rectifier 2. b) When C is increased ripple content decreases and dc output voltage becomes approximately equal to peak value of the input voltage. c) With increase in load current ripple content increases and the amplitude of voltage waveform deacreses Asignment 4 1 a) b) E C C c) B E 2 a) BJT's are used for signal amplification and can also be used as switches, for Voltage regulations and as oscillators. b) Darlington pair is used in the circuit of a cascaded amplifier to increase the output gain. 3) BJTs are available. at ratings of 1200V, 800A. The collector current rating of Darlington pair is 500mA 4. Examples :- a) Temperature sensors Logarithmic converters b) To Control the speed of a high power motor As an input stage of a touch-sensitive switch Assignment 5 1 a) Anode - + Cathode b) In normal applications ofzener diode current flows into the cathode and cathode is positive with respect to the anode. Uses:- As a Shunt Regulator Dc error Amplifier 2) 3) V With change in supply voltage ,we observe a very small change in output. While change in load current corresponds to more change in output Voltage than previous case but still very small and negligible. 4 ) Assignment 6 1) The MOSFETs or Metal-oxide semiconductor field effect transistor is the most widely used electronic device,especially in the design of integrated circuits. They are very small in size. They have three modes of operation; Cut off region Triode region Saturation 2) D S G G S D 3) 25 A, 400 V 4) Uses :- MOSFET analog switch Power MOSFETs are used in high end audio amplifiers 5) In electronics a comparator is a device which compares two voltages or currents and switches its output to indicate which is larger. A standard op-amp operating without negative feedback can be used as a comparator. When the non-inverting input (V+) is at a higher voltage than the inverting input (V-), the high gain of the op-amp causes it to output the most positive voltage it can. When the non-inverting input (V+) drops below the inverting input (V-), the op-amp outputs the most negative voltage it can. The input voltages must not exceed the power voltage range. Application :- A Flash ADC (also known as a Direct conversion ADC) is a type of analog-to-digital converter that uses a linear voltage ladder with a comparator. 6) Assignment 7 1) 2) Advantages and disadvantages :- Linear power circuits use heavy transformers compared to those in SMPs In Linear power circuits power is lost as heat, which is not the case in SMPs SMPs have mediocre power factors, while linear circuits have low power factor. SMPs are more vulnerable to give electric shock. SMPs are more suited for widely variable input voltages. 3) 4) Applications :- SMPs are used in Computers, Tv sets etc. Assignment 8 1 a) An SCR or a silicon-controlled rectifier is a 4-layer solid state device that controls current flow. In the normal "off" state the device restricts current flow to the leakage current. When the gate to cathode voltage exceeds a certain threshold, the device turns "on" and conducts current. b) A TRIAC, or TRIode for Alternating Current is an electronic component approximately equivalent to two SCRs joined in inverse parallel (paralleled but with the polarity reversed) and with their gates connected together. This results in a bidirectional electronic switch which can conduct current in either direction when it is turned on. It can be turned on by either a positive or a negative voltage being applied to its gate electrode. 2 a) b) Main terminal 2 3 ) SCRs are available with currents up to 200 amps and voltages up to 1000 volts in a variety of packages. TRIACs are available in current ratings up to 200 amps and voltages up to 1000 volts in a variety of packages.4 ) Examples or uses :- a) SCRs are used in power switching, phase control, chopper, battery charger, and inverter circuits . Industrially they are applied to produce variable DC voltages for motors from AC line voltage b) Low power TRIACs are used in many applications such as light dimmers, speed controls for electric fans and other electric motors They are also used in the modern computerized control circuits of many household small and major appliances. 5) Take the following circuit as an example: 6) Diode, thyristor, power MOSFET and IGBT (insulated gate bipolar transistor) Assignment 9 3) Computers operate using numbers and therefore there needs to be a way for a computer to convert letters (and other "characters") to and from numbers. A set of codes, known as "ASCII" (American Standard Code for Information Interchange) are used. These were initially developed for tasks such as sending documents to printers, and many of the commands make sense in this context. Conversion of numbers As an example of the use of ASCII, consider for example the problem of printing on a screen or printer the result of a numerical calculation. Suppose the number to be printed is (in binary) 01101100; the first step is to convert this into decimal; the answer is 108; this would be represented in the computer by the BCD codes of 0001, 0000, and 1000 (their Hex values of course are 1, 0 and 8). These need to be converted to their ASCII codes; they are (in Hex) 31, 30 and 38: or in binary, 0110001, 0110000 and 0111000. These are the codes which are sent to the printer, which will have been preprogrammed to recognise and print these codes as 108. Text Strings If text is being stored in a computer, it is usually stored as a string (a series of ASCII characters, each one of which is stored as one byte). The formatting characters such as space, carriage return and line feed may be included in the string. Suppose, for example, we wished to store the string Hello world! Including the space between the words, this has 12 characters. It would then be stored (writing the binary in hex) as 0C 48 65 6C 6C 6F 20 57 6F 72 6C 64 21 where 0C is the binary number representing 12. 6) CMOS devices can be damaged by voltages as low as 250V, so the first precaution to observe is to ensure that the handler is not carrying a static charge. An operative handling such devices in the course of their daily work may have an earthed mat on the bench and an earthed wrist strap to allow any charge to leak away, but for the amateur constructor such extreme precautions are really unnecessary. It is however wise to earth one's body momentarily before handling a CMOS IC and this can be done by touching the metal casing of any earthed electrical appliance which is plugged in but not switched on e.g. a cold soldering iron. Most CMOS ICs are equipped with internal protective diodes which limit voltages at the inputs to a safe level, but care is still advisable in handling them. If they have to be soldered in directly, the VDD pin should be connected before any earth connection is made. 4) The first integrated circuits contained only a few transistors. Called "Small-Scale Integration" (SSI), they used circuits containing transistors numbering in the tens. SSI circuits were crucial to early aerospace projects, and vice-versa. Both the Minuteman missile and Apollo program needed lightweight digital computers for their inertially-guided flight computers; the Apollo guidance computer led and motivated the integrated-circuit technology, while the Minuteman missile forced it into mass-production. The final step in the development process, starting in the 1980s and continuing through the present, was "Very Large-Scale Integration" (VLSI). This could be said to start with hundreds of thousands of transistors in the early 1980s, and continues beyond several hundred million transistors as of 2007. 8) Assignment 10 1) 2) 3) 4) Assignment 3 1) 3) 5,6) Using Foerier Series 7) DC component 8) Low Pass Filters used to limit the bandwidth of a signal before Analog to Digital Conversion (digital sampling) to obey the Sampling Theorem Bandpass filters to select a chosen 'narrowband' signal and reject unwanted noise or interference at other frequencies. Read More