SYSTEM INTEGRATION
Technology essentially based on radio-frequency identification (RFID).The RF Receiver and power harvester receives RF energy emitted from mobile phone towers and television transmission stations and convert it to electrical energy using RFID tags. Since this power is very feeble it is fed to a power management circuitry which performs voltage rectification and amplification and this electrical energy is stored in a storage capacitor.
The amount of energy that can be scavenged from the environment from machinery vibration is limited. Care must be taken in optimizing the generation and utilization of available power. A power budget is managed in the design and operation of the selfpowered sensor node. The approach often taken is to optimize each component. However, due to the coupling that exists among the elements, optimization of individual components will likely result in a suboptimal system design. A series of analytical laboratory studies were conducted to determine the power consumption characteristics of Sensor (accelerometer) Oil purifier Energy Converter Energy Storage(Capacitor bank) Power Conversion and Control Radio Circuit (802.15.4) Processor Energy Harvesting (piezo-electric cantilever beam) Energy Harvesting Module Power Bus Memory Environment the system elements. An FFT algorithm was implemented in a wireless sensor node as a representative calculation for machinery health assessment. While the percent of time is spent transmitting data is typically very small, the power requirements are significant (Figure 3). Power utilization in the self-powered sensor node may be optimized by judiciously balancing the amount of processing done locally in the sensor node with the amount of data that will be sent to a central processor for subsequent processing and analysis. The implication of this decision and the uncertainties in future processing demand and communications requirement provide the parameters for a dynamic optimization problem. The experimental results from the shipboard experiment provide realistic data to begin framing this optimization problem.
Scope of Energy Harvesting
Scope of Energy Harvesting
Advanced technical developments have increased the efficiency of devices in capturing trace amounts of energy from the environment and transforming them into electrical energy. In addition, advancements in microprocessor technology have increased power efficiency, effectively reducing power consumption requirements. In combination, these developments have sparked interest in the engineering community to develop more and more applications that utilize energy harvesting for power.
Energy harvesting from a natural source where a remote application is deployed, and where such natural energy source is essentially inexhaustible, is an increasingly attractive alternative to inconvenient wall plugs and costly batteries. This essentially free energy source, when designed and installed properly, is available maintenance-free and is now available throughout the lifetime of the application. Such systems can be more reliable than wall plugs or batteries.
In addition, energy harvesting can be used as an alternative energy source to supplement a primary power source and to enhance the reliability of the overall system and prevent power interruptions. The history of energy harvesting dates back to the windmill and the waterwheel. People have searched for ways to store the energy from heat and vibrations for many decades. One driving force behind the search for new energy harvesting devices is the desire to power sensor networks and mobile devices without batteries. Energy harvesting is also motivated by a desire to address the issue of climate change and global warming.
The main motivation factors for the implimentation of the RF Energy harvesting are
n Advancements in microprocessor technology- The advanced microprocessors need less power consumption
n Advanced technical developments – Even Minute amount of Energy can be harvested
n A battery alone has a short lifetime
n Solar cells has its limitations
n A steady growth in the distances over which the tags can communicate
Advanced technical developments have increased the efficiency of devices in capturing trace amounts of energy from the environment and transforming them into electrical energy. In addition, advancements in microprocessor technology have increased power efficiency, effectively reducing power consumption requirements. In combination, these developments have sparked interest in the engineering community to develop more and more applications that utilize energy harvesting for power.
Energy harvesting from a natural source where a remote application is deployed, and where such natural energy source is essentially inexhaustible, is an increasingly attractive alternative to inconvenient wall plugs and costly batteries. This essentially free energy source, when designed and installed properly, is available maintenance-free and is now available throughout the lifetime of the application. Such systems can be more reliable than wall plugs or batteries.
In addition, energy harvesting can be used as an alternative energy source to supplement a primary power source and to enhance the reliability of the overall system and prevent power interruptions. The history of energy harvesting dates back to the windmill and the waterwheel. People have searched for ways to store the energy from heat and vibrations for many decades. One driving force behind the search for new energy harvesting devices is the desire to power sensor networks and mobile devices without batteries. Energy harvesting is also motivated by a desire to address the issue of climate change and global warming.
The main motivation factors for the implimentation of the RF Energy harvesting are
n Advancements in microprocessor technology- The advanced microprocessors need less power consumption
n Advanced technical developments – Even Minute amount of Energy can be harvested
n A battery alone has a short lifetime
n Solar cells has its limitations
n A steady growth in the distances over which the tags can communicate
Classification of Energy Harvesting devices
Classification of Energy Harvesting devices
We may classify the different energy harvesting devices in two ways: considering who or what provides the energy for conversion, and what type of energy is converted. Table 2 relates the two classification schemes. In the first classification scheme we can distinguish between two kinds of devices. First, devices that use part of the energy of the user of the electronic appliance. It will usually be a human, but it could be also an animal , for example for a remote monitoring device. We call this first kind of devices
The second kind of energy harvesting device gets its energy from the environment, and thus we call them Environment Energy devices. This classification takes into account that, following the first principle of thermodynamics, a greater amount of energy must be spent to obtain a certain amount of electrical energy. In the case of Human Power it is the user that in some way or other provides this energy and, though the energy levels are very small, the effect may prove noticeable when several devices depend on the activity of a single use.
In order to evaluate the burden of energy harvesting on user activities, it is possible to use a simple biomechanical model to calculate the energy involved in a human step,11 obtaining around 40 J. In comparison, the energy of a short RF transmission can be evaluated in the order of 100 μW. This means that the extra energy demanded to obtain enough energy is very small for some applications, and therefore it makes sense to consider human beings as a possible energy source
The second classification scheme may consider three types of energy: kinetic, electromagnetic radiation (including light and RF), and thermal. For Human Energy devices only kinetic and thermal energy are available. In the case of kinetic Human energy, one may distinguish between those actions made specifically to generate energy and casual movements made during normal behavior. These two cases are called by the Human Power research group of the Delft University of Technology12 Active and Passive Human Energy respectively. Following this definition, thermal Human Energy is always passive. Environment Energy sources include kinetic energy in the form of vibrations, radiation as solar energy or RF radiation, and thermal energy. The energy harvesting devices may pick up vibrations when located on machines, building elements or other places near vibrating sources. Radiation may come from natural or artificial sources. Thermal energy depends on the existence of a temperature gradient. While the transducing methods may be similar to the Human Energy devices, the excitation magnitudes, frequency spectra and periodicity are very different, and therefore each case must be studied separately. This will also have consequences in the electrical power conditioning circuit.
We may classify the different energy harvesting devices in two ways: considering who or what provides the energy for conversion, and what type of energy is converted. Table 2 relates the two classification schemes. In the first classification scheme we can distinguish between two kinds of devices. First, devices that use part of the energy of the user of the electronic appliance. It will usually be a human, but it could be also an animal , for example for a remote monitoring device. We call this first kind of devices
The second kind of energy harvesting device gets its energy from the environment, and thus we call them Environment Energy devices. This classification takes into account that, following the first principle of thermodynamics, a greater amount of energy must be spent to obtain a certain amount of electrical energy. In the case of Human Power it is the user that in some way or other provides this energy and, though the energy levels are very small, the effect may prove noticeable when several devices depend on the activity of a single use.
In order to evaluate the burden of energy harvesting on user activities, it is possible to use a simple biomechanical model to calculate the energy involved in a human step,11 obtaining around 40 J. In comparison, the energy of a short RF transmission can be evaluated in the order of 100 μW. This means that the extra energy demanded to obtain enough energy is very small for some applications, and therefore it makes sense to consider human beings as a possible energy source
The second classification scheme may consider three types of energy: kinetic, electromagnetic radiation (including light and RF), and thermal. For Human Energy devices only kinetic and thermal energy are available. In the case of kinetic Human energy, one may distinguish between those actions made specifically to generate energy and casual movements made during normal behavior. These two cases are called by the Human Power research group of the Delft University of Technology12 Active and Passive Human Energy respectively. Following this definition, thermal Human Energy is always passive. Environment Energy sources include kinetic energy in the form of vibrations, radiation as solar energy or RF radiation, and thermal energy. The energy harvesting devices may pick up vibrations when located on machines, building elements or other places near vibrating sources. Radiation may come from natural or artificial sources. Thermal energy depends on the existence of a temperature gradient. While the transducing methods may be similar to the Human Energy devices, the excitation magnitudes, frequency spectra and periodicity are very different, and therefore each case must be studied separately. This will also have consequences in the electrical power conditioning circuit.
ENERgy Harvesting
ENERgy Harvesting
Energy Harvesting is the process of capturing minute amounts of energy from one or more of these naturally-occurring energy sources, accumulating them and storing them for later use. Energy-harvesting devices efficiently and effectively capture, accumulate, store, condition and manage this energy and supply it in a form that can be used to perform a helpful task. Similarly, an Energy Harvesting Module is an electronic device that can perform all these functions to power a variety of sensor and control circuitry for intermittent duty applications.
Energy harvesting (also known as Power harvesting or energy scavenging) is the process by which energy is captured and stored. Frequently this term is applied when speaking about small autonomous devices, like those used in sensor networks. A variety of different sources exist for harvesting energy, such as solar power, thermal energy, wind energy, salinity gradients and kinetic energy.
Traditionally electrical power has been generated from fossil fuels in large, centralized plants. Large-scale ambient energy, such as sun, wind and tides, is widely available but trickier to harvest. In urban areas, there is a surprising amount of electromagnetic energy in the environment as a result of radio and television broadcasting.
Energy harvesting devices converting ambient energy into electrical energy have attracted much interest in both the military and commercial sectors. Some systems convert random motion, such as that of ocean waves, into electricity to be used by oceanographic monitoring sensors for autonomous operation. Future applications may include high power output devices (or arrays of such devices) deployed at remote locations to serve as reliable power stations for large systems. All of these devices must be sufficiently robust to endure long-term exposure to hostile environments and have a broad range of dynamic sensitivity to exploit the entire spectrum of wave motions.
Energy can also be harvested to power small autonomous sensors such as those developed using MEMS technology. These systems are often very small and require little power, but their applications are limited by the reliance on battery power. Scavenging energy from ambient vibrations, heat or light could enable smart sensors to be functional indefinitely. Several academic groups have been involved in the analysis and development of vibration-powered energy harvesting technology, including the Control and Power Group and Optical and Semiconductor Devices Group at Imperial College London, MIT, UC Berkeley and Southampton University.
Typical power densities available from energy harvesting devices are highly dependent upon the specific application and design of the harvesting generator. For motion powered devices , typical values are a few μW/cc for human body powered applications and hundreds of μW/cc for generators powered from machinery.
Energy Harvesting is the process of capturing minute amounts of energy from one or more of these naturally-occurring energy sources, accumulating them and storing them for later use. Energy-harvesting devices efficiently and effectively capture, accumulate, store, condition and manage this energy and supply it in a form that can be used to perform a helpful task. Similarly, an Energy Harvesting Module is an electronic device that can perform all these functions to power a variety of sensor and control circuitry for intermittent duty applications.
Energy harvesting (also known as Power harvesting or energy scavenging) is the process by which energy is captured and stored. Frequently this term is applied when speaking about small autonomous devices, like those used in sensor networks. A variety of different sources exist for harvesting energy, such as solar power, thermal energy, wind energy, salinity gradients and kinetic energy.
Traditionally electrical power has been generated from fossil fuels in large, centralized plants. Large-scale ambient energy, such as sun, wind and tides, is widely available but trickier to harvest. In urban areas, there is a surprising amount of electromagnetic energy in the environment as a result of radio and television broadcasting.
Energy harvesting devices converting ambient energy into electrical energy have attracted much interest in both the military and commercial sectors. Some systems convert random motion, such as that of ocean waves, into electricity to be used by oceanographic monitoring sensors for autonomous operation. Future applications may include high power output devices (or arrays of such devices) deployed at remote locations to serve as reliable power stations for large systems. All of these devices must be sufficiently robust to endure long-term exposure to hostile environments and have a broad range of dynamic sensitivity to exploit the entire spectrum of wave motions.
Energy can also be harvested to power small autonomous sensors such as those developed using MEMS technology. These systems are often very small and require little power, but their applications are limited by the reliance on battery power. Scavenging energy from ambient vibrations, heat or light could enable smart sensors to be functional indefinitely. Several academic groups have been involved in the analysis and development of vibration-powered energy harvesting technology, including the Control and Power Group and Optical and Semiconductor Devices Group at Imperial College London, MIT, UC Berkeley and Southampton University.
Typical power densities available from energy harvesting devices are highly dependent upon the specific application and design of the harvesting generator. For motion powered devices , typical values are a few μW/cc for human body powered applications and hundreds of μW/cc for generators powered from machinery.
Unique characteristics of a WSN include
Unique characteristics of a WSN include:
· Limited power they can harvest or store
· Ability to withstand harsh environmental conditions
· Ability to cope with node failures
· Mobility of nodes
· Dynamic network topology
· Communication failures
· Unattended operation
· Heterogeneity of nodes
· Large scale deployment
· Limited power they can harvest or store
· Ability to withstand harsh environmental conditions
· Ability to cope with node failures
· Mobility of nodes
· Dynamic network topology
· Communication failures
· Unattended operation
· Heterogeneity of nodes
· Large scale deployment
WIRELESS SENSORS
WIRELESS SENSORS
A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions , such as temperature , sound, vibration , pressure , motion or pollutants , at different locations . The development of wireless sensor networks was originally motivated by military applications such as attlefield surveillance . However , wireless sensor networks are now used in many civilian application areas , including environment and habitat monitoring, healthcare applications, home automation, and traffic control.
In addition to one or more sensors , each node in a sensor network is typically equipped with a radio transceiver or other wireless communications device, a small microcontrolle r, and an energy source, usually a battery. The envisaged size of a single sensor node can vary from shoebox-sized nodes down to devices the size of grain of dust , although functioning 'motes' of genuine microscopic dimensions have yet to be created.The cost of sensor nodes is similarly variable, ranging from hundreds of dollars to a few cents , depending on the size of the sensor network and the complexity required of individual sensor nodes. Size and cost constraints on sensor node result in corresponding constraints on resources such as energy, memory, computational speed and bandwidth.A sensor network normally constitutes a wireless a d - hoc network , meaning that each sensor supports a multi – hop routing algorithm ( several nodes may forward data packets to the base station).
A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions , such as temperature , sound, vibration , pressure , motion or pollutants , at different locations . The development of wireless sensor networks was originally motivated by military applications such as attlefield surveillance . However , wireless sensor networks are now used in many civilian application areas , including environment and habitat monitoring, healthcare applications, home automation, and traffic control.
In addition to one or more sensors , each node in a sensor network is typically equipped with a radio transceiver or other wireless communications device, a small microcontrolle r, and an energy source, usually a battery. The envisaged size of a single sensor node can vary from shoebox-sized nodes down to devices the size of grain of dust , although functioning 'motes' of genuine microscopic dimensions have yet to be created.The cost of sensor nodes is similarly variable, ranging from hundreds of dollars to a few cents , depending on the size of the sensor network and the complexity required of individual sensor nodes. Size and cost constraints on sensor node result in corresponding constraints on resources such as energy, memory, computational speed and bandwidth.A sensor network normally constitutes a wireless a d - hoc network , meaning that each sensor supports a multi – hop routing algorithm ( several nodes may forward data packets to the base station).
RF Radiation
RF Radiation
RF radiation is employed to power ID cards by directing high power electromagnetic energy to the devices from a nearby source. In addition to energy, it is possible to send information as well. However, the term energy harvesting implies that it is the same device which gets its energy from the environment. In cities and very populated areas there is a large number of potential RF sources: broadcast radio and tv, mobile telephony, wireless networks, etc. The problem is collecting all these disparate sources and converting them in useful energy. The conversion is based on a rectifying antenna (rectenna), constructed with a Schottky diode located between the antenna dipoles. The energy levels actually present are so low that no present electronic device can use them. However, future technologies may allow the fabrication of lower power devices that would “recycle” RF energy generated for other purposes by different elements
RF radiation is employed to power ID cards by directing high power electromagnetic energy to the devices from a nearby source. In addition to energy, it is possible to send information as well. However, the term energy harvesting implies that it is the same device which gets its energy from the environment. In cities and very populated areas there is a large number of potential RF sources: broadcast radio and tv, mobile telephony, wireless networks, etc. The problem is collecting all these disparate sources and converting them in useful energy. The conversion is based on a rectifying antenna (rectenna), constructed with a Schottky diode located between the antenna dipoles. The energy levels actually present are so low that no present electronic device can use them. However, future technologies may allow the fabrication of lower power devices that would “recycle” RF energy generated for other purposes by different elements
RADIO FREQUENCY
RADIO FREQUENCY
Electromagnetic radiations consists of waves of electric and magnetic energy moving together ( that is , radiating ) through space at the speed of light. Taken together, all forms of electromagnetic energy are referred to as the electromagnetic spectrum. Radio waves and microwaves emitted by transmitting antennas are one form of electro magnetic energy . Often the term electromagnetic field or radio frequency (RF) field may be used to indicate the presence of electromagnetic or RF energy. An RF field has both an electric and a magnetic component (electric field and magnetic field), and it is often convenient to express the intensity of the RF environment at a given location in terms of units specific for each component. For example, the unit "volts per meter" (V/m) is used to measure the strength of the electric field and the unit "amperes per meter" (A/m) is used to express the strength of the magnetic field.
RF waves can be characterized by a wavelength and a frequency. The wavelength is the distance covered by one complete cycle of the electromagnetic wave, while the frequency is the number of electromagnetic waves passing a given point in one second. The frequency of an RF signal is usually expressed in terms of a unit called the hertz (Hz). One Hz equals one cycle per second. One megahertz (MHz) equals one million cycles per second. Different forms of electromagnetic energy are categorized by their wavelengths and frequencies. The RF part of the electromagnetic spectrum is generally defined as that part of the spectrum where electromagnetic waves have frequencies in the range of about 3 kilohertz (3 kHz) to 300 gigahertz (300 GHz).
Electromagnetic radiations consists of waves of electric and magnetic energy moving together ( that is , radiating ) through space at the speed of light. Taken together, all forms of electromagnetic energy are referred to as the electromagnetic spectrum. Radio waves and microwaves emitted by transmitting antennas are one form of electro magnetic energy . Often the term electromagnetic field or radio frequency (RF) field may be used to indicate the presence of electromagnetic or RF energy. An RF field has both an electric and a magnetic component (electric field and magnetic field), and it is often convenient to express the intensity of the RF environment at a given location in terms of units specific for each component. For example, the unit "volts per meter" (V/m) is used to measure the strength of the electric field and the unit "amperes per meter" (A/m) is used to express the strength of the magnetic field.
RF waves can be characterized by a wavelength and a frequency. The wavelength is the distance covered by one complete cycle of the electromagnetic wave, while the frequency is the number of electromagnetic waves passing a given point in one second. The frequency of an RF signal is usually expressed in terms of a unit called the hertz (Hz). One Hz equals one cycle per second. One megahertz (MHz) equals one million cycles per second. Different forms of electromagnetic energy are categorized by their wavelengths and frequencies. The RF part of the electromagnetic spectrum is generally defined as that part of the spectrum where electromagnetic waves have frequencies in the range of about 3 kilohertz (3 kHz) to 300 gigahertz (300 GHz).
ABSTRACT
Stealth aircraft are aircraft that use stealth technology to make it harder to be detected by radar and other means than conventional aircraft by employing a combination of features to reduce visibility in the visual, audio, infrared and radio frequency (RF) spectrum. While no aircraft is totally invisible to radar, stealth aircraft limit current conventional radar's abilities to detect or track them effectively enough to prevent an attack. Stealth is accomplished by using a complex design philosophy to reduce the ability of an opponent's sensors to detect, track and attack an aircraft. An airplane made with faceted surfaces could have a very low radar signature because the surfaces would radiate almost all of the radar energy away from the receiver. Reduced radar cross section is only one of five factors that designers addressed to create a truly stealthy design. Designers also addressed making the aircraft less visible to the naked eye, controlling radio transmissions, and noise abatement.
Stealth aircraft are aircraft that use stealth technology to make it harder to be detected by radar and other means than conventional aircraft by employing a combination of features to reduce visibility in the visual, audio, infrared and radio frequency (RF) spectrum. While no aircraft is totally invisible to radar, stealth aircraft limit current conventional radar's abilities to detect or track them effectively enough to prevent an attack. Stealth is accomplished by using a complex design philosophy to reduce the ability of an opponent's sensors to detect, track and attack an aircraft. An airplane made with faceted surfaces could have a very low radar signature because the surfaces would radiate almost all of the radar energy away from the receiver. Reduced radar cross section is only one of five factors that designers addressed to create a truly stealthy design. Designers also addressed making the aircraft less visible to the naked eye, controlling radio transmissions, and noise abatement.
ANALOG CIRCUITS
ANALOG CIRCUITS
1. The breakdown voltage of a transistor with its base open is BVCEO and with emitter open is BVCBO, then
(a) BVCEO < BVCBO
(b) BVCEO = BVCBO
(c) BVCEO > BVCBO
(d) Both voltages are unrelated
2. The threshold voltage of an n-channel MOSFET can be increased by
(a) increasing the channel doping concentration
(b) reducing the channel length
(c) reducing gate oxide thickness
(d) decreasing channel doping concentration
3. As the temperature is increased, the voltage across a diode carrying a contant current
(a) increases
(b) decreases
(c) remains constant
(d) may increase or decrease depending upon the doping levels in the junction
4. A series RLC circuit when excited by a 10V sinusoidal voltage source of variable frequency, exbits resonance of 100Hz and has a 3 dB bandwidth of 5 Hz. The voltage across inductor L at resonance is
(a)10 V
(b)10√2 V
(c) 10/√2 V
(d) 200 V
5. A CE amplifier has resistor RF connected between collector and base RF = 40 k.
RC = 4k. Given hfe = 50, rπ= 1k, the output resistance R0d is given by
(a) 40 k
(b) 20 k
(c) 4 k
(d) 0.66 k
6. When two identical stages with upper cutoff at wn are cascaded, the over all B db
point is
(a) 1 ωH
(b) 2 ωH
(c) 0.5 ωH
(d) 0.64 ωH
7. The parameters of FET are gm = 95 mA / volt total capacitance = 500 pf. For a voltage
gain of -30, the bandwidth will be
(a) 333 Ω
(b) 3 kΩ
(c) 2.7 kΩ
(d) 300 Ω
8. FET tuned amplifier with gm = 5Ma/V. rd = 20 k has a resonance impedence of 20 kΩ.
The gain resonance is given by
(a) 200
(b) 100
(c) 50
(d) 25
9. A cascade ICis now available for tuned PF and IF amplifiers. The significant which
make it attractive is
(a) high value of input impedence
(b )high value of current gain
(c) low value of h12
(d) low value of output impedence
10. In a class A series fed amplifier using a transistor, under ideal conditions, the
maximum ac power delivered is 1 watt. The maximum transistor dissipation
capability has to be
(a) 1 watts
(b) 2 watts
(c) 3 watts
(d) 4 watts
11. An npn transistor has a beta cut-off frequency fb of 1MHz, and emitter short circuit
low frequency current gain β0 of 200. the unity gain frequency ft and the alpha cut off
frequency fα respectively are
(a) 200 MHz,201 MHz
(b) 200 MHz ,199 MHz
(c) 199 MHz,200 MHz
(d) 201 MHz,200MHz
1. The breakdown voltage of a transistor with its base open is BVCEO and with emitter open is BVCBO, then
(a) BVCEO < BVCBO
(b) BVCEO = BVCBO
(c) BVCEO > BVCBO
(d) Both voltages are unrelated
2. The threshold voltage of an n-channel MOSFET can be increased by
(a) increasing the channel doping concentration
(b) reducing the channel length
(c) reducing gate oxide thickness
(d) decreasing channel doping concentration
3. As the temperature is increased, the voltage across a diode carrying a contant current
(a) increases
(b) decreases
(c) remains constant
(d) may increase or decrease depending upon the doping levels in the junction
4. A series RLC circuit when excited by a 10V sinusoidal voltage source of variable frequency, exbits resonance of 100Hz and has a 3 dB bandwidth of 5 Hz. The voltage across inductor L at resonance is
(a)10 V
(b)10√2 V
(c) 10/√2 V
(d) 200 V
5. A CE amplifier has resistor RF connected between collector and base RF = 40 k.
RC = 4k. Given hfe = 50, rπ= 1k, the output resistance R0d is given by
(a) 40 k
(b) 20 k
(c) 4 k
(d) 0.66 k
6. When two identical stages with upper cutoff at wn are cascaded, the over all B db
point is
(a) 1 ωH
(b) 2 ωH
(c) 0.5 ωH
(d) 0.64 ωH
7. The parameters of FET are gm = 95 mA / volt total capacitance = 500 pf. For a voltage
gain of -30, the bandwidth will be
(a) 333 Ω
(b) 3 kΩ
(c) 2.7 kΩ
(d) 300 Ω
8. FET tuned amplifier with gm = 5Ma/V. rd = 20 k has a resonance impedence of 20 kΩ.
The gain resonance is given by
(a) 200
(b) 100
(c) 50
(d) 25
9. A cascade ICis now available for tuned PF and IF amplifiers. The significant which
make it attractive is
(a) high value of input impedence
(b )high value of current gain
(c) low value of h12
(d) low value of output impedence
10. In a class A series fed amplifier using a transistor, under ideal conditions, the
maximum ac power delivered is 1 watt. The maximum transistor dissipation
capability has to be
(a) 1 watts
(b) 2 watts
(c) 3 watts
(d) 4 watts
11. An npn transistor has a beta cut-off frequency fb of 1MHz, and emitter short circuit
low frequency current gain β0 of 200. the unity gain frequency ft and the alpha cut off
frequency fα respectively are
(a) 200 MHz,201 MHz
(b) 200 MHz ,199 MHz
(c) 199 MHz,200 MHz
(d) 201 MHz,200MHz
SAMPLE AND HOLD CIRCUIT
SAMPLE AND HOLD CIRCUIT
AIM:
To set up a sample and hold circuit and to study its operation.
COMPENENTS AND EQUIPMENTS REQUIRED:
Op-amp, function generator, CRO, BFW 10, resistors and capacitors.
THEORY:
A Sample and Hold circuit samples an input signal and holds on to its last sampled value until the input is sampled again. This type of circuit is very useful in digital interfacing and analog to digital and pulse code modulation systems. One of the simplest practical sample and Hold circuit configuration is shown in the figure. The n-channel
E-MOSFET works as a switch and controlled by the control voltage Vc and the capacitor C stores the charge. The analog signal Vs to be sampled is applied to the drain of
E-MOSFET and the control voltage Vc is applied to its gate. When Vc is positive, the E-MOSFET turns on and the capacitor C charges to the instantaneous value of input Vs with a time constant [Ro+rDS(on). Here Ro is the o/p resistance of the voltage follower A1 and rds(on) is the resistance of the MOSFET when on. Thus the i/p voltage Vs appears across the capacitor C and then at the o/p through the voltage follower A2.
During the time when control voltage Vc is zero, the E-MOSFET is OFF. The capacitor C is now facing the high input impedance of voltage follower A2 and hence cannot discharge. The capacitor holds the voltage across it. The time period Ts, the time during which the voltage across the capacitor is equal to input voltage is called Sample period. The time period TH of Vc during which the voltage across the capacitor is held constant is called Hold period. The frequency of the control voltage should be kept higher than (at least twice) the input so as to retrieve the input from output waveform.
PROCEDURE:
1. Connections are made as shown in the figure.
2. Feed pulse to the input of this circuit and note down the output.
RESULT:
Sample and hold circuit is setup and studied.
AIM:
To set up a sample and hold circuit and to study its operation.
COMPENENTS AND EQUIPMENTS REQUIRED:
Op-amp, function generator, CRO, BFW 10, resistors and capacitors.
THEORY:
A Sample and Hold circuit samples an input signal and holds on to its last sampled value until the input is sampled again. This type of circuit is very useful in digital interfacing and analog to digital and pulse code modulation systems. One of the simplest practical sample and Hold circuit configuration is shown in the figure. The n-channel
E-MOSFET works as a switch and controlled by the control voltage Vc and the capacitor C stores the charge. The analog signal Vs to be sampled is applied to the drain of
E-MOSFET and the control voltage Vc is applied to its gate. When Vc is positive, the E-MOSFET turns on and the capacitor C charges to the instantaneous value of input Vs with a time constant [Ro+rDS(on). Here Ro is the o/p resistance of the voltage follower A1 and rds(on) is the resistance of the MOSFET when on. Thus the i/p voltage Vs appears across the capacitor C and then at the o/p through the voltage follower A2.
During the time when control voltage Vc is zero, the E-MOSFET is OFF. The capacitor C is now facing the high input impedance of voltage follower A2 and hence cannot discharge. The capacitor holds the voltage across it. The time period Ts, the time during which the voltage across the capacitor is equal to input voltage is called Sample period. The time period TH of Vc during which the voltage across the capacitor is held constant is called Hold period. The frequency of the control voltage should be kept higher than (at least twice) the input so as to retrieve the input from output waveform.
PROCEDURE:
1. Connections are made as shown in the figure.
2. Feed pulse to the input of this circuit and note down the output.
RESULT:
Sample and hold circuit is setup and studied.
Amplifier
THEORY
This is the most popular op amp circuit discussed first.
Inverting amplifier
This is the most popular op amp circuit. The polarity of the input voltage get inverted at the output. If a sine wave is fed to the input of the amplifier, output will be amplified sine wave of with 180º phase shift. The gain of the inverting amplifier is given by A= -Rf/Ri , where Rf is the feedback resistance and Ri is the input resistance. It can be used as a scalar as by varying either Rf or Ri, output amplitude can be varied.
Non-inverting amplifier
The circuit provides a gain to the input signal without any change in polarity. Gain is given by A= 1+(Rf/Ri), where Rf is feedback resistance and Ri is the input resistance.
Special case: Voltage follower
It is a non inverting amplifier with unity gain. Here the output voltage is equal to and in phase with the input. So here output follows the input.
PROCEDURE
1. Set up the inverting amplifier as shown in the circuit diagram.
2. Feed a 2 VPP, 50 Hz sinusoidal input and observe the input and output wave forms.
3. Calculate gain A= Vo/Vi.
4. Keep the amplitude of the input constant and vary the input frequency from 50Hz to 2MHz.
5. Measure the output amplitude corresponding to different frequencies and enter it in tabular columns.
6. Plot the frequency response of the circuit.
7. Repeat the procedure for non-inverting amplifier also.
This is the most popular op amp circuit discussed first.
Inverting amplifier
This is the most popular op amp circuit. The polarity of the input voltage get inverted at the output. If a sine wave is fed to the input of the amplifier, output will be amplified sine wave of with 180º phase shift. The gain of the inverting amplifier is given by A= -Rf/Ri , where Rf is the feedback resistance and Ri is the input resistance. It can be used as a scalar as by varying either Rf or Ri, output amplitude can be varied.
Non-inverting amplifier
The circuit provides a gain to the input signal without any change in polarity. Gain is given by A= 1+(Rf/Ri), where Rf is feedback resistance and Ri is the input resistance.
Special case: Voltage follower
It is a non inverting amplifier with unity gain. Here the output voltage is equal to and in phase with the input. So here output follows the input.
PROCEDURE
1. Set up the inverting amplifier as shown in the circuit diagram.
2. Feed a 2 VPP, 50 Hz sinusoidal input and observe the input and output wave forms.
3. Calculate gain A= Vo/Vi.
4. Keep the amplitude of the input constant and vary the input frequency from 50Hz to 2MHz.
5. Measure the output amplitude corresponding to different frequencies and enter it in tabular columns.
6. Plot the frequency response of the circuit.
7. Repeat the procedure for non-inverting amplifier also.
Pressure exchanger
Pressure exchanger
A pressure exchanger transfers pressure energy from a high pressure fluid stream to a low pressure fluid stream. Many industrial processes operate at elevated pressures and have high pressure waste streams. One way of providing a high pressure fluid to such a process is to transfer the waste pressure to a low pressure stream using a pressure exchanger.
One particularly efficient type of pressure exchanger is a rotary pressure exchanger. This device uses a cylindrical rotor with longitudinal ducts parallel to its rotational axis. The rotor spins inside a sleeve between two end covers. Pressure energy is transferred directly from the high pressure stream to the low pressure stream in the ducts of the rotor. Some fluid that remains in the ducts serves as a barrier that inhibits mixing between the streams.. The ducts of the rotor charge and discharge as the pressure transfer process repeats itself.
Reverse Osmosis with Pressure Exchangers One application in which pressure exchangers are widely used is reverse osmosis (RO). In an RO system, pressure exchangers are used as energy recovery devices (ERD).High pressure membrane concentrate from the membranes is directed to the ERD. Pressure transfers from the high pressure concentrate stream to a low pressure feed water stream. Pressurized feed water flows from the ERD, driven by a circulation pump. This stream merges with the output of a high pressure pump to form the membrane feed stream [E]. The concentrate leaves the ERD at low pressure, expelled by the incoming feed water flow.
Pressure exchangers save energy in these systems by reducing the load on the high pressure pump. In the pressure exchanger the energy contained in the brine is transferred hydraulically and with an efficiency of approximately 98% to the feed. This reduces the energy demand for the desalination process significantly and thus the operating costs.
A pressure exchanger transfers pressure energy from a high pressure fluid stream to a low pressure fluid stream. Many industrial processes operate at elevated pressures and have high pressure waste streams. One way of providing a high pressure fluid to such a process is to transfer the waste pressure to a low pressure stream using a pressure exchanger.
One particularly efficient type of pressure exchanger is a rotary pressure exchanger. This device uses a cylindrical rotor with longitudinal ducts parallel to its rotational axis. The rotor spins inside a sleeve between two end covers. Pressure energy is transferred directly from the high pressure stream to the low pressure stream in the ducts of the rotor. Some fluid that remains in the ducts serves as a barrier that inhibits mixing between the streams.. The ducts of the rotor charge and discharge as the pressure transfer process repeats itself.
Reverse Osmosis with Pressure Exchangers One application in which pressure exchangers are widely used is reverse osmosis (RO). In an RO system, pressure exchangers are used as energy recovery devices (ERD).High pressure membrane concentrate from the membranes is directed to the ERD. Pressure transfers from the high pressure concentrate stream to a low pressure feed water stream. Pressurized feed water flows from the ERD, driven by a circulation pump. This stream merges with the output of a high pressure pump to form the membrane feed stream [E]. The concentrate leaves the ERD at low pressure, expelled by the incoming feed water flow.
Pressure exchangers save energy in these systems by reducing the load on the high pressure pump. In the pressure exchanger the energy contained in the brine is transferred hydraulically and with an efficiency of approximately 98% to the feed. This reduces the energy demand for the desalination process significantly and thus the operating costs.
1. Some months have 30 days, some months have 31 days. How many months have 28 days?
2. If a doctor gives you 3 pills and tells you to take one pill every half hour, how long would it be before all
the pills had been taken?
3. I went to bed at eight 8 'clock in the evening and wound up my clock and set the alarm to sound at nine
9 'clock in the morning. How many hours sleep would I get before being awoken by the alarm?
4. Divide 30 by half and add ten. What do you get?
5. A farmer had 17 sheep. All but 9 died. How many live sheep were left?
6. If you had only one match and entered a COLD and DARK room, where there was an oil heater, an oil
lamp and a candle, which would you light first?
8. Take 2 apples from 3 apples. What do you have?
9. How many animals of each species did Moses take with him in the Ark?
answers
All of them. Every month has at least 28 days.
•
1 hour. If you take a pill at 1 o'clock, then another at 1.30 and the last at 2'clock, they will be taken in 1 hour.
•
1 hour. It is a wind up alarm clock which cannot discriminate between a.m. and p.m.
•
70. Dividing by half is the same as multiplying by 2.
•
9 live sheep.
•
The match.
•
2 apples.
•
None. It was Noah, not Moses.
Name the most recent year in which New Year's preceded Christmas ANSWER
Why are 1968 pennies worth more than 1967 pennies? ANSWER
A 10 foot rope ladder hangs over the side of a boat with the bottom rung on the surface of the water. The rungs are one foot apart, and the tide goes up at the rate of 6 inches per hour. How long will it be until three rungs are covered? ANSWER
I asked the assistant in the hardware store, "How much will one cost?" "Twenty cents" she replied. "And how much will twelve cost?" I asked. "Forty cents." she replied. "OK, I'll take one hundred and twelve." How much did I pay? ANSWERIf you had only one match, and entered a dark room containing an oil lamp, some newspaper, and some kindling wood, which would you light first? ANSWER
If Mr Smith's peacock lays an egg in Mr Jones' yard, who owns the egg? ANSWER
Mrs Brown's bungalow is decorated entirely in pink. The carpet, lampshades, ceiling, walls etc. are all pink. What color are her stairs? ANSWER
What was the (American) President's name in 1960? ANSWER
Is noon AM or PM? ANSWER
If there are 6 apples and you take away 4, how many do you have? ANSWER
What is the maximum number of times a normal sheet of (news)paper can be folded in half by hand? ANSWER
Who's bigger: Mr. Bigger, Mrs. Bigger or their baby? ANSWER
How many animals of each sex did Moses take with him on the ark?ANSWER
If a plane crashes on the border between the US and Mexico, where do they bury the survivors? ANSWER
How much dirt is there in a hole 3 feet deep, 6 ft long and 4 ft wide? ANSWER
An electric train is moving north at 100mph and a wind is blowing to the west at 10mph. Which way does the smoke blow? ANSWER
A farmer had 15 sheep, and all but 8 died. How many are left? ANSWER
Imagine you are driving a bus. When you start your trip there are an old lady named Johnson and a long-haired kid on the bus. At the first stop the lady leaves and a businessman enters. At the next stop Frankie, a young boy, enters with his little sister. Then three old ladies who have been shopping in the mall get on. After a short trip the long-haired kid leaves the bus and a man and lady enter. Paul with his dog Blue gets on, while Frankie and his sister get off, and, finally, the bus arrives at the bus station. What is the name of the bus driver?ANSWER
If you spell "sit all day in the tub" S-O-A-K, and you spell "a funny story" J-O-K-E, how do you spell "the white of an egg"? ANSWER
Is it legal for a man to marry his widow's sister? ANSWER
How many birth days does the average person have? ANSWER
What familiar word starts with IS, ends with AND, and has LA in the middle? ANSWER
How many legs does an elephant have if you count his trunk as a leg?ANSWER
Who created this pointless list of Tricky Questions?ANSWER
What do you sit on, sleep on, and brush your teeth with?ANSWER
Why is it against the law for a man living in North Carolina to be buried in South Carolina? ANSWER
There was an airplane crash, every single person on board died, but yet two people survived. How is this possible? ANSWER
That attorney is my brother, testified the accountant. But the attorney testified he didn't have a brother. Who is lying? ANSWER
Before Mount Everest was discovered, what was the highest mountain in the world?ANSWER
Eskimos are very good hunters, but they never hunt penguins. Why not? ANSWER
Some months have 31 days, others have 30 days. How many have 28 days? ANSWER
A man and his son were in an automobile accident. The man died on the way to the hospital, but the boy was rushed into surgery. The emergency room surgeon said "I can't operate, that's my son!" How is this possible?ANSWER
If marriages were made in heaven then what was made in HELL!!!!! Days after marriage
1) There are 8 Apples on the table, you take 3. How many do you have? 2) 10 Birds in a field. 2 were shot, how many were left?
3) Take away the first letter, take away the last letter, then take away all the other letters. What do you have left? 4) If you have 4 melons in one hand, and 7 apples in the other - What do you have? 5) A box has nine ears of corn in it. A Squirrel carries out three ears a day, and yet it takes him nine days to carry out all the corn. Explain? 6) Why do white sheep eat more than black sheep? 7) A man wanted to plant 4 trees, but all 4 had to be equal distances from each other. How did he do it? 8) I have 2 coins in my hand that add up to 60c. One of the coins isn't a 50c piece. What are the coins? 9) A fisherman was asked how long was the fish he had caught. He said "it is 30cms plus half its length" How long was the fish? 10) A Hammer and a Nail cost $31. If the Hammer cost $30 more than the Nail, what is the cost of each? 11) It takes 7 men 2 hours to build a wall. How long does it take 3 men to build the same wall? 12) "I will bet you $1" said Fred, "that if you give me $2, I will give you $3 in return." "Done," replied Tom. Was he? 13) "How much will one cost?" "25 cents" "How much will fifteen cost?" "50 cents" "OK then, I'll take one hundred and sixteen" "Thank you, that will be 75 cents please" Explain. 14) What comes next in the following sequence ? 1, 4, 5, 6, 7, 9, 11,... 15) In a scientific context, what could the following phrase mean? How I want a drink, alcoholic of course, after the heavy chapters involving quantum mechanics Answers: 1) If you take 3 then you have 3. 2) 2 - the others flew away. 3) The Mailman. 4) Big hands. 5) He has 2 of his own ears, so he carries out only 1 ear of corn per day. 6) There are more white sheep than black sheep. 7) He planted 3 trees at the corners of an equilateral triangle. He built a mound in the middle and planted the 4th on the top of the mound so that it was the same distance from the other 3 trees. (on the points of a tetrahedron.) 8) 50c and a 10c (The coin that isn't a 50c piece is a 10c. The other coin is the 50c). 9) 60 cms. 10) Hammer $30.50, Nail $0.50 11) No need to bother, the 7 men have already built it. 12) Tom accepts the bet, gives Fred $2. Fred does not give Tom $3 so loses the bet and has to pay Tom $1. Result Fred gains $1. 13) He is buying house numbers, each separate digit costs 25c, so 116 is three digits so 3 x 25c = 75c. 14) 100 (The next number that doesn't contain a "T" in the spelling). 15) The number of letters in each word refers to pi to 14 decimal places, i.e. 3.14159265358979
1. In what year did Christmas and New Year's fall in the same year?2. Why are 1990 American dollar bills worth more than 1989 Americandollar bills?3. How could you rearrange the letters in the words "new door" to makeone word? Note: There is only one correct answer.4. Even if they are starving, natives living in the Arctic will nevereat a penguin's egg. Why not?5. Which is correct to say, "The yolk of the egg are white" or "Theyolk of the egg is white"?6. There were an electrician and a plumber waiting in line foradmission to the "International Home Show". One of them was the fatherof the other's son. How could this be possible?7. After the new Canon Law that took effect on November 27, 1983,would a Roman Catholic man be allowed to marry his widow's sister?Answers1. They fall in the same year every year, New Year's Day just arrivesvery early in the year and Christmas arrives very late in the sameyear.2. One thousand nine hundred and ninety dollar bills are worth onedollar more than one thousand nine hundred and eighty-nine dollarbills.3. "one word"4. Penguins live in the Antarctic.5. Neither, the yolk of the egg is yellow.6. They were husband and wife.7. He can't because he's dead.1.HIGGS’S PIGSFarmer Higgs owns three pink pigs, four brown pigs, and one black pig.How many of Higgs’s pigs can say that it is the same color as anotherpig on Higgs’s farm? _____________2. PENNIES FOR SALEWhy are 1984 pennies worth almost twenty dollars in 1994? _____________3. THE TRAMP AND THE TRAINA tramp was walking down a railroad track when he saw a fast expresstrain speeding toward him. Of course, he jumped off the track. Butbefore he jumped, he ran ten feet toward the train. Why?______________________________4. A HARD-BOILED PROBLEMIf it takes twenty minutes to hard-boil one goose egg, how long willit take to hard-boil four goose eggs? ____________5. HEAP TOUGH PROBLEMA big fat Indian and a small thin Indian were sitting outside ateepee, each smoking a pipe. The little Indian was the son of the bigIndian, but the big Indian was not the little Indian’s father. Howcome? _________________________________6. STAMPS TO STUMP YOUIt takes twelve one-cent stamps to make a dozen. How many four-centstamps does it take to make a dozen?___________7. BETSY AND PATSY"We were born on the same day of the same year," said Betsy."And we have the same mother and father," said Patsy."But we’re not twins," said Betsy.Can you explain? ___________________________________8. THE PURPLE PARROT"I guarantee," said the salesman in the pet shop, "that this purpleparrot will repeat every word it hears." A customer bought the bird,but found that the parrot wouldn’t speak a single word. Nevertheless,what the salesman said was true. How could this be?Answers1. Zero. Pigs can’t talk.2. 1,984 pennies is just 16 cents less than $20.4. 20 minutes.5. The big Indian was his mother.6. 12.7. They are triplets.8. The parrot was deaf.1. How could the 22nd and 24th U.S. Presidents have the sameparents, but weren’t brothersAns: Grover Cleveland was elected twice to become the 22nd and 24thU.S President.2. Eskimos are very good hunters, but they never hunt penguins. Why not?Ans: Eskimos live at the North pole, penguins at the south pole.3 The Mississippi River is the dividing line between Tennessee andArkansas. If an airplane crashed exactly in the middle of theMississippi River there, where would the survivors be buried?.Ans : You do not bury survivors.3. Before Mount Everest was discovered, what was the highestmountain in the world?Ans: Mount Everest was still the highest mountain even before it was discovered.4. What in an automobile engine serves no purpose but without itthe engine does not work?Ans; Noise5. What is light as a feather, but even the strongest man cannothold it more than a few minutes?Ans: His Breath1) A man is born in 1972 and died in 1952 at the age of 25Ans: he’s born in room number 1972 of a hospital and dies in roomnumber 1952 at the age of 25.2) A man rides into town on Friday. He stays one night and leaveson Friday.Ans: the town is near North Pole. Night lasts for 6 months.3) Harry dropped a sugar cube in his coffee then lifted it outintact a minute later.Ans: It was instant coffee no water has been added yet.4) Amy drives her car due west for a quarter mile, withoutturning. When she stops, the car is facing east.Ans: she droves the car backward.5) A married couple goes to a movie. During the movie the husbandstrangles the wife. He is able to get her body home without attractingattention.Ans: The movie is at drive in theater.6) An ordinary woman walks on water.Ans: it is easy to walk on a lake surface when lake is frozen.
2. If a doctor gives you 3 pills and tells you to take one pill every half hour, how long would it be before all
the pills had been taken?
3. I went to bed at eight 8 'clock in the evening and wound up my clock and set the alarm to sound at nine
9 'clock in the morning. How many hours sleep would I get before being awoken by the alarm?
4. Divide 30 by half and add ten. What do you get?
5. A farmer had 17 sheep. All but 9 died. How many live sheep were left?
6. If you had only one match and entered a COLD and DARK room, where there was an oil heater, an oil
lamp and a candle, which would you light first?
8. Take 2 apples from 3 apples. What do you have?
9. How many animals of each species did Moses take with him in the Ark?
answers
All of them. Every month has at least 28 days.
•
1 hour. If you take a pill at 1 o'clock, then another at 1.30 and the last at 2'clock, they will be taken in 1 hour.
•
1 hour. It is a wind up alarm clock which cannot discriminate between a.m. and p.m.
•
70. Dividing by half is the same as multiplying by 2.
•
9 live sheep.
•
The match.
•
2 apples.
•
None. It was Noah, not Moses.
Name the most recent year in which New Year's preceded Christmas ANSWER
Why are 1968 pennies worth more than 1967 pennies? ANSWER
A 10 foot rope ladder hangs over the side of a boat with the bottom rung on the surface of the water. The rungs are one foot apart, and the tide goes up at the rate of 6 inches per hour. How long will it be until three rungs are covered? ANSWER
I asked the assistant in the hardware store, "How much will one cost?" "Twenty cents" she replied. "And how much will twelve cost?" I asked. "Forty cents." she replied. "OK, I'll take one hundred and twelve." How much did I pay? ANSWERIf you had only one match, and entered a dark room containing an oil lamp, some newspaper, and some kindling wood, which would you light first? ANSWER
If Mr Smith's peacock lays an egg in Mr Jones' yard, who owns the egg? ANSWER
Mrs Brown's bungalow is decorated entirely in pink. The carpet, lampshades, ceiling, walls etc. are all pink. What color are her stairs? ANSWER
What was the (American) President's name in 1960? ANSWER
Is noon AM or PM? ANSWER
If there are 6 apples and you take away 4, how many do you have? ANSWER
What is the maximum number of times a normal sheet of (news)paper can be folded in half by hand? ANSWER
Who's bigger: Mr. Bigger, Mrs. Bigger or their baby? ANSWER
How many animals of each sex did Moses take with him on the ark?ANSWER
If a plane crashes on the border between the US and Mexico, where do they bury the survivors? ANSWER
How much dirt is there in a hole 3 feet deep, 6 ft long and 4 ft wide? ANSWER
An electric train is moving north at 100mph and a wind is blowing to the west at 10mph. Which way does the smoke blow? ANSWER
A farmer had 15 sheep, and all but 8 died. How many are left? ANSWER
Imagine you are driving a bus. When you start your trip there are an old lady named Johnson and a long-haired kid on the bus. At the first stop the lady leaves and a businessman enters. At the next stop Frankie, a young boy, enters with his little sister. Then three old ladies who have been shopping in the mall get on. After a short trip the long-haired kid leaves the bus and a man and lady enter. Paul with his dog Blue gets on, while Frankie and his sister get off, and, finally, the bus arrives at the bus station. What is the name of the bus driver?ANSWER
If you spell "sit all day in the tub" S-O-A-K, and you spell "a funny story" J-O-K-E, how do you spell "the white of an egg"? ANSWER
Is it legal for a man to marry his widow's sister? ANSWER
How many birth days does the average person have? ANSWER
What familiar word starts with IS, ends with AND, and has LA in the middle? ANSWER
How many legs does an elephant have if you count his trunk as a leg?ANSWER
Who created this pointless list of Tricky Questions?ANSWER
What do you sit on, sleep on, and brush your teeth with?ANSWER
Why is it against the law for a man living in North Carolina to be buried in South Carolina? ANSWER
There was an airplane crash, every single person on board died, but yet two people survived. How is this possible? ANSWER
That attorney is my brother, testified the accountant. But the attorney testified he didn't have a brother. Who is lying? ANSWER
Before Mount Everest was discovered, what was the highest mountain in the world?ANSWER
Eskimos are very good hunters, but they never hunt penguins. Why not? ANSWER
Some months have 31 days, others have 30 days. How many have 28 days? ANSWER
A man and his son were in an automobile accident. The man died on the way to the hospital, but the boy was rushed into surgery. The emergency room surgeon said "I can't operate, that's my son!" How is this possible?ANSWER
If marriages were made in heaven then what was made in HELL!!!!! Days after marriage
1) There are 8 Apples on the table, you take 3. How many do you have? 2) 10 Birds in a field. 2 were shot, how many were left?
3) Take away the first letter, take away the last letter, then take away all the other letters. What do you have left? 4) If you have 4 melons in one hand, and 7 apples in the other - What do you have? 5) A box has nine ears of corn in it. A Squirrel carries out three ears a day, and yet it takes him nine days to carry out all the corn. Explain? 6) Why do white sheep eat more than black sheep? 7) A man wanted to plant 4 trees, but all 4 had to be equal distances from each other. How did he do it? 8) I have 2 coins in my hand that add up to 60c. One of the coins isn't a 50c piece. What are the coins? 9) A fisherman was asked how long was the fish he had caught. He said "it is 30cms plus half its length" How long was the fish? 10) A Hammer and a Nail cost $31. If the Hammer cost $30 more than the Nail, what is the cost of each? 11) It takes 7 men 2 hours to build a wall. How long does it take 3 men to build the same wall? 12) "I will bet you $1" said Fred, "that if you give me $2, I will give you $3 in return." "Done," replied Tom. Was he? 13) "How much will one cost?" "25 cents" "How much will fifteen cost?" "50 cents" "OK then, I'll take one hundred and sixteen" "Thank you, that will be 75 cents please" Explain. 14) What comes next in the following sequence ? 1, 4, 5, 6, 7, 9, 11,... 15) In a scientific context, what could the following phrase mean? How I want a drink, alcoholic of course, after the heavy chapters involving quantum mechanics Answers: 1) If you take 3 then you have 3. 2) 2 - the others flew away. 3) The Mailman. 4) Big hands. 5) He has 2 of his own ears, so he carries out only 1 ear of corn per day. 6) There are more white sheep than black sheep. 7) He planted 3 trees at the corners of an equilateral triangle. He built a mound in the middle and planted the 4th on the top of the mound so that it was the same distance from the other 3 trees. (on the points of a tetrahedron.) 8) 50c and a 10c (The coin that isn't a 50c piece is a 10c. The other coin is the 50c). 9) 60 cms. 10) Hammer $30.50, Nail $0.50 11) No need to bother, the 7 men have already built it. 12) Tom accepts the bet, gives Fred $2. Fred does not give Tom $3 so loses the bet and has to pay Tom $1. Result Fred gains $1. 13) He is buying house numbers, each separate digit costs 25c, so 116 is three digits so 3 x 25c = 75c. 14) 100 (The next number that doesn't contain a "T" in the spelling). 15) The number of letters in each word refers to pi to 14 decimal places, i.e. 3.14159265358979
1. In what year did Christmas and New Year's fall in the same year?2. Why are 1990 American dollar bills worth more than 1989 Americandollar bills?3. How could you rearrange the letters in the words "new door" to makeone word? Note: There is only one correct answer.4. Even if they are starving, natives living in the Arctic will nevereat a penguin's egg. Why not?5. Which is correct to say, "The yolk of the egg are white" or "Theyolk of the egg is white"?6. There were an electrician and a plumber waiting in line foradmission to the "International Home Show". One of them was the fatherof the other's son. How could this be possible?7. After the new Canon Law that took effect on November 27, 1983,would a Roman Catholic man be allowed to marry his widow's sister?Answers1. They fall in the same year every year, New Year's Day just arrivesvery early in the year and Christmas arrives very late in the sameyear.2. One thousand nine hundred and ninety dollar bills are worth onedollar more than one thousand nine hundred and eighty-nine dollarbills.3. "one word"4. Penguins live in the Antarctic.5. Neither, the yolk of the egg is yellow.6. They were husband and wife.7. He can't because he's dead.1.HIGGS’S PIGSFarmer Higgs owns three pink pigs, four brown pigs, and one black pig.How many of Higgs’s pigs can say that it is the same color as anotherpig on Higgs’s farm? _____________2. PENNIES FOR SALEWhy are 1984 pennies worth almost twenty dollars in 1994? _____________3. THE TRAMP AND THE TRAINA tramp was walking down a railroad track when he saw a fast expresstrain speeding toward him. Of course, he jumped off the track. Butbefore he jumped, he ran ten feet toward the train. Why?______________________________4. A HARD-BOILED PROBLEMIf it takes twenty minutes to hard-boil one goose egg, how long willit take to hard-boil four goose eggs? ____________5. HEAP TOUGH PROBLEMA big fat Indian and a small thin Indian were sitting outside ateepee, each smoking a pipe. The little Indian was the son of the bigIndian, but the big Indian was not the little Indian’s father. Howcome? _________________________________6. STAMPS TO STUMP YOUIt takes twelve one-cent stamps to make a dozen. How many four-centstamps does it take to make a dozen?___________7. BETSY AND PATSY"We were born on the same day of the same year," said Betsy."And we have the same mother and father," said Patsy."But we’re not twins," said Betsy.Can you explain? ___________________________________8. THE PURPLE PARROT"I guarantee," said the salesman in the pet shop, "that this purpleparrot will repeat every word it hears." A customer bought the bird,but found that the parrot wouldn’t speak a single word. Nevertheless,what the salesman said was true. How could this be?Answers1. Zero. Pigs can’t talk.2. 1,984 pennies is just 16 cents less than $20.4. 20 minutes.5. The big Indian was his mother.6. 12.7. They are triplets.8. The parrot was deaf.1. How could the 22nd and 24th U.S. Presidents have the sameparents, but weren’t brothersAns: Grover Cleveland was elected twice to become the 22nd and 24thU.S President.2. Eskimos are very good hunters, but they never hunt penguins. Why not?Ans: Eskimos live at the North pole, penguins at the south pole.3 The Mississippi River is the dividing line between Tennessee andArkansas. If an airplane crashed exactly in the middle of theMississippi River there, where would the survivors be buried?.Ans : You do not bury survivors.3. Before Mount Everest was discovered, what was the highestmountain in the world?Ans: Mount Everest was still the highest mountain even before it was discovered.4. What in an automobile engine serves no purpose but without itthe engine does not work?Ans; Noise5. What is light as a feather, but even the strongest man cannothold it more than a few minutes?Ans: His Breath1) A man is born in 1972 and died in 1952 at the age of 25Ans: he’s born in room number 1972 of a hospital and dies in roomnumber 1952 at the age of 25.2) A man rides into town on Friday. He stays one night and leaveson Friday.Ans: the town is near North Pole. Night lasts for 6 months.3) Harry dropped a sugar cube in his coffee then lifted it outintact a minute later.Ans: It was instant coffee no water has been added yet.4) Amy drives her car due west for a quarter mile, withoutturning. When she stops, the car is facing east.Ans: she droves the car backward.5) A married couple goes to a movie. During the movie the husbandstrangles the wife. He is able to get her body home without attractingattention.Ans: The movie is at drive in theater.6) An ordinary woman walks on water.Ans: it is easy to walk on a lake surface when lake is frozen.
Ultra-low power microcontrollers
Ultra-low power microcontrollers
for embedded security applications
Engineers developing modern security systems
like smoke detectors and intruder alarms
have seen quite a change in the methods they
can employ to realize their applications. Fixed
function solutions built from a number of components
have given way to fully integrated fast
response systems. In the past, ASIC solutions
for front-end signal conditioning, data conversion
and, in the case of bus-based systems, for
communication purposes were quite popular
and frequently used. These solutions, however,
did not offer the flexibility to react quickly to
changes in the market environment such as the
introduction of different types of sensors and
new communication standards.
The constraints imposed by fixed-function
ASIC systems mean that adaptive systems, capable
of compensating for temperature fluctuations,
aging sensor behaviour and other external
influences like higher environmental noise
levels, cannot be easily built-in. Miniaturization,
increased networking capabilities and
data logging features are additional drivers for
modern, flexible solutions in this area. A typical
motion detector front-end based on a passive
infrared (PIR) sensor is shown in figure 2.
This system amplifies the signal from the PIR
sensor in two stages, which are compared
using a comparator device. This outputs a high
signal if movement is detected, which is indicated
on a direct user display, or is communicatedto a central unit in a bigger security system.
However, this fixed function does not allow for
on-the-fly adjustment should the parameters
change and, even more importantly, consumes
a current in the range of 80 μA, which does not
help the life-cycle of battery-powered systems.
By contrast, a PIR motion detector system
based on the new MSP430F20x3 microcontroller
for embedded security applications
Engineers developing modern security systems
like smoke detectors and intruder alarms
have seen quite a change in the methods they
can employ to realize their applications. Fixed
function solutions built from a number of components
have given way to fully integrated fast
response systems. In the past, ASIC solutions
for front-end signal conditioning, data conversion
and, in the case of bus-based systems, for
communication purposes were quite popular
and frequently used. These solutions, however,
did not offer the flexibility to react quickly to
changes in the market environment such as the
introduction of different types of sensors and
new communication standards.
The constraints imposed by fixed-function
ASIC systems mean that adaptive systems, capable
of compensating for temperature fluctuations,
aging sensor behaviour and other external
influences like higher environmental noise
levels, cannot be easily built-in. Miniaturization,
increased networking capabilities and
data logging features are additional drivers for
modern, flexible solutions in this area. A typical
motion detector front-end based on a passive
infrared (PIR) sensor is shown in figure 2.
This system amplifies the signal from the PIR
sensor in two stages, which are compared
using a comparator device. This outputs a high
signal if movement is detected, which is indicated
on a direct user display, or is communicatedto a central unit in a bigger security system.
However, this fixed function does not allow for
on-the-fly adjustment should the parameters
change and, even more importantly, consumes
a current in the range of 80 μA, which does not
help the life-cycle of battery-powered systems.
By contrast, a PIR motion detector system
based on the new MSP430F20x3 microcontroller
SAMPLE AND HOLD CIRCUIT
AIM:
To set up a sample and hold circuit and to study its operation.
COMPENENTS AND EQUIPMENTS REQUIRED:
Op-amp, function generator, CRO, BFW 10, resistors and capacitors.
THEORY:
A Sample and Hold circuit samples an input signal and holds on to its last sampled value until the input is sampled again. This type of circuit is very useful in digital interfacing and analog to digital and pulse code modulation systems. One of the simplest practical sample and Hold circuit configuration is shown in the figure. The n-channel
E-MOSFET works as a switch and controlled by the control voltage Vc and the capacitor C stores the charge. The analog signal Vs to be sampled is applied to the drain of
E-MOSFET and the control voltage Vc is applied to its gate. When Vc is positive, the E-MOSFET turns on and the capacitor C charges to the instantaneous value of input Vs with a time constant [Ro+rDS(on). Here Ro is the o/p resistance of the voltage follower A1 and rds(on) is the resistance of the MOSFET when on. Thus the i/p voltage Vs appears across the capacitor C and then at the o/p through the voltage follower A2.
During the time when control voltage Vc is zero, the E-MOSFET is OFF. The capacitor C is now facing the high input impedance of voltage follower A2 and hence cannot discharge. The capacitor holds the voltage across it. The time period Ts, the time during which the voltage across the capacitor is equal to input voltage is called Sample period. The time period TH of Vc during which the voltage across the capacitor is held constant is called Hold period. The frequency of the control voltage should be kept higher than (at least twice) the input so as to retrieve the input from output waveform.
PROCEDURE:
1. Connections are made as shown in the figure.
2. Feed pulse to the input of this circuit and note down the output.
RESULT: Sample and hold circuit is setup and studied
To set up a sample and hold circuit and to study its operation.
COMPENENTS AND EQUIPMENTS REQUIRED:
Op-amp, function generator, CRO, BFW 10, resistors and capacitors.
THEORY:
A Sample and Hold circuit samples an input signal and holds on to its last sampled value until the input is sampled again. This type of circuit is very useful in digital interfacing and analog to digital and pulse code modulation systems. One of the simplest practical sample and Hold circuit configuration is shown in the figure. The n-channel
E-MOSFET works as a switch and controlled by the control voltage Vc and the capacitor C stores the charge. The analog signal Vs to be sampled is applied to the drain of
E-MOSFET and the control voltage Vc is applied to its gate. When Vc is positive, the E-MOSFET turns on and the capacitor C charges to the instantaneous value of input Vs with a time constant [Ro+rDS(on). Here Ro is the o/p resistance of the voltage follower A1 and rds(on) is the resistance of the MOSFET when on. Thus the i/p voltage Vs appears across the capacitor C and then at the o/p through the voltage follower A2.
During the time when control voltage Vc is zero, the E-MOSFET is OFF. The capacitor C is now facing the high input impedance of voltage follower A2 and hence cannot discharge. The capacitor holds the voltage across it. The time period Ts, the time during which the voltage across the capacitor is equal to input voltage is called Sample period. The time period TH of Vc during which the voltage across the capacitor is held constant is called Hold period. The frequency of the control voltage should be kept higher than (at least twice) the input so as to retrieve the input from output waveform.
PROCEDURE:
1. Connections are made as shown in the figure.
2. Feed pulse to the input of this circuit and note down the output.
RESULT: Sample and hold circuit is setup and studied
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