0
Electronics Engineering
Electronics Engineering is a branch of engineering that deals with practical applications of electronic components, devices, systems, or equipment. Electronics are devices that operate on low voltage sources, as in electron tubes, transistors, integrated circuits, and printed circuit boards and use electricity as part of its driving force.
24,372 Questions
Plc's are used for a variety of applications. Namely automation and machine industries as it is cost effective, time effective and a much more reliable source of "computer" than the traditional relay controllers. They are capable of withstanding harsh environments such as heat, cold, moist areas. Programmable Logic Controllers are obviously programmable to carry out certain program executions using 'ladder logic' in order to activate certain outputs when the condition are met with the inputs.
Added
'Programmed Logic Controllers' keep the cost of cabling down and simplify interlocks and logic control.
A complex control panel, can control a complex system and the only things connecting them, will be a power supply line and a small data cable.
Heavy duty power cables can be kept short and local to the machinery being controlled. The switches and indicator lamps only deal with minute control signals. The function is passed to a local PLC receiver via a small data cable.
Instead of a complex system of relays and wiring, interlocks are controlled by a computer program, which enables changes to be made without re-wiring.
For example, certain pump motors can only be started when the correct valves are open. This can be dealt with by a program instead of physical wiring.
What are the advantage of semiconductor over conductor?
semiconductors are the conducors they are partially conduct electricity. And we can increase therir conductivity by using various method . They are Intrinsic method and extrinsic method . Intrinsic method is heating the semiconducter . Extrinsic method is doping. By using this method the conductivity of semiconductors is rapidly increases. Then we use semiconductors are prefferd to conductors
Describe the difference between majority and minority carriers?
FOR n-type semiconductor the majority charge carrier is electron and for n-type semiconductor it is hole.
the majority and minority charge carrier is result of free electron and hole.
the majority charge carrier is responsible for transport of electron.
Disadvantage of using printed circuit board?
When comparing them to breadboards and stripboards:
Advantages - it is a permanent method of producing a circuit
- they are custom made so can be very small
- they can be mass produced and so economical
Disadvantages - can't be modified once printed (has to be completely re-designed)
- can't change components
How do you reduce the hysteresis loss?
Hysteresis losses are a function of the magnetic characteristics of the magnetic circuit, so there is very little you can do to minimise hysteresis losses other than to reduce the primary voltage to a transformer if that is at all practicable. These losses are really in the hands of the manufacturers who design and manufacture magnetic circuits.
How are digital and analog signals similar?
They both convey differences in voltage level. An anologue signal can send any level between limits. A digital signal only sends two different levels, one represents a 1 or high level, the other represents 0 or low level.
Why do you put a diode across a relay coil?
If the current through a coil is interrupted, the coil generates a high voltage (such as in the old car ignition coils). The diode provides a path for the current to decay naturally, thus avoiding the high voltage.
What is the difference between power consumption and power dissipation?
A: POWER consumption is total power usage power dissipation is wasted power in the form of heat, IR drop and so on.
When silicon is doped with phosphorous what type of semiconductor results?
it would be a n-type semiconductor because phosphorus has more valence electrons than silicon does.
What is the maximum length of a PS2 cable?
There are cables up to 50 feet for sale, but if you want to modify one yourself, you can make it as long as you want, if you have enough wire (try using telephone wire). You can also get wireless controllers, and wireless AV connections.
What engineering applications use second order derivatives?
Second order derivative is used in many fields of engineering. One of its application is used in solving problems related to dynamics of rigid bodies and in determination of forces and strength of materials.
Advantages of carry look ahead adder?
You use a look ahead carry adder to reduce the propagation delay effects caused by the ripple carry that would otherwise be used. With ripple carry, each stage is dependent on the preceding stage, and this is cumulative. With look ahead carry, the carries are computed in parallel, speeding up the overall process.
What are the advantages of using fiber optic cable?
1. Immunity to Electromagnetic Interference
Although fiber optics can solve data communications problems, they are not needed everywhere. Most computer data goes over ordinary wires. Most data is sent over short distances at low speed. In ordinary environments, it is not practical to use fiber optics to transmit data between personal computers and printers as it's too costly. Electromagnetic Interference is a common type of noise that originates with one of the basic properties of electromagnetism. Magnetic field lines generate an electrical current as they cut across conductors. The flow of electrons in a conductor generates a magnetic field that changes with the current flow. Electromagnetic Interference does occur in coaxial cables, since current does cut across the conductor. Fiber optics are immune to this EMI since signals are transmitted as light instead of current. Thus, they can carry signals through places where EMI would block transmission.
2. Data Security
Magnetic fields and current induction work in two ways. They don't just generate noise in signal carrying conductors; they also let the information on the conductor to be leaked out. Fluctuations in the induced magnetic field outside a conductor carry the same information as the current passing through the conductor. Shielding the wire, as in coaxial cables can reduce the problem, but sometimes shielding can allow enough signal leak to allow tapping, which is exactly what we wouldn't want.
There are no radiated magnetic fields around optical fibers; the electromagnetic fields are confined within the fiber. That makes it impossible to tap the signal being transmitted through a fiber without cutting into the fiber. Since fiber optics do not radiate electromagnetic energy, emissions cannot be intercepted and physically tapping the fiber takes great skill to do undetected. Thus, the fiber is the most secure medium available for carrying sensitive data.
3. Non Conductive Cables
Metal cables can encounter other signal transmission problems because of subtle variations in electrical potential. Electronic designers assume that ground is a uniform potential. That is reasonable if ground is a single metal chassis, and it's not too bad if ground is a good conductor that extends through a small building. However, the nominal ground potential can differ by several volts if cables run between different buildings or sometimes even different parts of the same building.
Signal levels in semiconductor circuits are just a few volts, creating a problem known as ground loop. When the difference in ground potential at two ends of a wire gets comparable to the signal level, stray currents begin to cause noise. If the differences grow large enough, they can even damage components. Electric utilities have the biggest problems because their switching stations and power plants may have large potential differences.
A serious concern with outdoor cables in certain computer networks is that they can be hit by lightning, causing destruction to wires and other cables that are involved in the network. Certain computer companies are aware of this problem and trying to solve it by having protective devices for wire circuits to block current and voltage surges.
Any conductive cables can carry power surges or ground loops. Fiber optic cables can be made non-conductive by avoiding metal in their design. These kinds of cables are economical and standard for many indoor applications. Outdoor versions are more expensive since they require special strength members, but they can still be valuable in eliminating ground loops and protecting electronic equipment from surge damage.
4. Eliminating Spark Hazards
In some cases, transmitting signals electrically can be extremely dangerous. Most electric potentials create small sparks. The sparks ordinarily pose no danger, but can be really bad in a chemical plant or oil refinery where the air is contaminated with potentially explosive vapours. One tiny spark can create a big explosion. potential spark hazards seriously hinder data and communication in such facilities. Fiber optic cables do not produce sparks since they do not carry current.
5. Ease Of Installation
Increasing transmission capacity of wire cables generally makes them thicker and more rigid. Such thick cables can be difficult to install in existing buildings where they must go through walls and cable ducts. Fiber cables are easier to install since they are smaller and more flexible. They can also run along the same routes as electric cables without picking up excessive noise.
One way to simplify installation in existing buildings is to run cables through ventilation ducts. However, fire codes require that such plenum cables be made of costly fire retardant materials that emit little smoke. The advantage of fiber types is that they are smaller and hence require less of the costly fire retardant materials. The small size, lightweight and flexibility of fiber optic cables also make them easier to be used in temporary or portable installations.
6. High Bandwidth Over Long Distances
Fiber optics have a large capacity to carry high speed signals over longer distances without repeaters than other types of cables. The information carrying capacity increases with frequency. This however, doesn't mean that optical fiber has infinit bandwidth, but it's certainly greater than coaxial cables. Generally, coaxial cables have a bandwidth parameter of a few MHz/km, where else the fiber optic cable has a bandwidth of 400MHz/km. (These figures are just approximations and do vary from cable to cable!) This is an important factor that leads to the choice of fiber for data communications. Fiber can be added to a wire network so it can reach terminals outside its normal range.
The three main advantages are:
Speed - Fibre-optic cable is capable of transmitting data at a MUCH faster rate than copper cable.
Signal - Copper cable loses signal readily with length, and has to be boosted at regular intervals. The signal in Fibre-optic cable doesn't deteriorate nearly as much over distance and requires less boosting.
Capacity - Copper cable (using analogue signals) can only carry ONE signal at a time. Fibre-optic cable (using digital signals) can carry many data 'streams' as you just encode each stream so it gets to the right destination.
How does a capacitor store energy?
The energy stored in a capacitor is almost entirely in the electric field produced between the plates. It takes energy from a battery or some other power source to move electrons to one of the plates and away from the other. This makes one plate positively charged and the other negatively charged. Electric field is produced in proportion to the charge per unit area on a plate, and this electric field is said to originate on positive charges and terminate on negative charges.
Energy stored in electric fields is proportional to the square of the electric field strength and the volume of the field.
The energy is transferred from the power source to the electric field through the rearrangement of electrical charges.
What would be the resistance of an ideal voltmeter?
The theoretical resistance (idea resistance) of an ammeter is zero. With a voltmeter, it's infinitely high.
In some analog meters the full scale deflection is produced by only about 50 microamps. Actually that does not change from ammeter to voltmeter, just the configuration of the meter's external "connection circuit"changes.
Simple ammeters are 'connected in series' devices. The resistance of such an ammeter must be kept very low because, if it were a high resistance, that would seriously limit the current allowed into the circuit and would impair the circuit's function.
Voltmeters are 'connected in parallel' devices. The theoretical resistance of a volt meter is very high, the higher the better. It is checking the potential between two points, so, to have the least effect on the circuit it is measuring, it must draw as little current as possible.
Name three tools that you can use to protect a system against ESD as you work on it?
ANSI/ESD S20.20 covers the requirements of an ESD control program.
The fundamental ESD control principles are:
- Ground all conductors, including personnel
- Insulators are high charging and cannot be grounded. Remove all non-essential insulators. Keep all process essential insulators at least 12" from ESDS or neutralize charges with ionizers
- Outside an EPA, ESDS are to be packaged in closed ESD shielding bags or covered containers having shielding properties
Grounding works great removing electrostatic charges. If opening a computer and handling circuit boards or electronics, the person should be grounded using a wrist strap connected to the ground of an AC electrical outlet or equipment ground. The ESD sensitive items should be placed on a grounded mat. A good tool to have is a Field Service Kit which includes a mat, a cord to ground the mat, and a wrist strap to ground the person.
If attachment to the ground of an AC electrical outlet is not possible, one can use equipotential bonding.
"When neither AC equipment [Equipment Grounding Conductor] or auxiliary grounds are available, an equipotential bonding system may need to be used. In this situation, all of the items in the system are bonded together so that the charge that resides on the elements will be shared equally and therefore there will be no potential difference between the items. Once this step has been completed it is safe to handle ESD sensitive parts without inducing damage. A real life example of this is often observed in office equipment field service operations. For safety reasons the service technician will often disconnect the AC power cord which detaches the equipment from ground. In order to safely install ESD sensitive products into the equipment, it is necessary to electrically connect or bond together the service technician, the equipment frame and the ESD sensitive product. Once bonded together an ESD event will NOT occur when the technician handles the product or installs it in the office equipment." [ESD Handbook ESD TR20.20-2008 section 5.1.3 Basic Grounding Requirements]
How do you convert analog signal to digital signal?
Various analog to digital converters are available for this purpose. They are basically made up of operational amplifiers.
The other way is to convert the analog signal into samples. Then converting these samples into quantization levels. These quantization levels are then converted into 1s and 0s.
Compare between center tap rectifier and bridge rectifier?
Parameter HWR FVR FVBR 1 No. of Diodes 1 2 4 2 Need of Centre tapping in secondary of the transformer winding No Yes No 3 Average dc voltage Edc Em/π 2Em/π 2Em/π 4 Average d.c. current Idc Im/π 2Im/π 2Im/π 5 RMS value of Current IRMS Im/2 Im/ Im/ 6 Ripple Factor γ 1.21 0.48 0.48 7 Ripple Frequency f 2f 2f 8 Maximum Rectification Efficiency η 40.6 % 81.2 % 81.2 % 9 Average Diode Current Idc Idc/2 Idc/2 10 Form Factor 1.57 1.11 1.11 11 Filtering Difficult Easy Easy 12 Voltage Drop in Diode Less Less More 13 PIV Em 2Em Em 14 T.U.F. (TRANSFORMER UTILISATION FACTOR) 0.287 0.693 0.812 15 Applications Less In low In High voltage Voltage rectifiers rect.
It depends on what you're doing and what you have available.
If you can find a good center tapped transformer with the target voltage, that will save you 2 diodes.
If you're going for the "quick and dirty" solution and you don't have a center tapped transformer, a bridge rectifier is an excellent way to get dirty DC.
It is a model for the equivalent circuit of a Transistor.
What is the current in a 12volt circuit that has 9 ohms of resistance?
Ohm's Law: Current equals voltage divided by resistance
If the two 3 ohm resistors are in series, then 12 volts divided by 6 ohms is 2 amperes.
If the two 3 ohm resistors are in parallel, then 12 volts divided by 1.5 ohms is 8 amperes.
WARNING: In the first case, this is 24 watts or 12 watts per resistor. In the second case, this is 96 watts or 48 watts per resistor. Exercise great care if you intend to duplicate this in the lab, i.e. do not think for even a split second that a 1/4 watt resistor is going to be able to handle this power without burning up and causing a fire.
How does schmitt trigger differ from bistable multivibrator?
Schmitt trigger refers to an input hysteresis mechanism to improve the noise tolerance of a digital input, preventing glitch generation or false triggering on outputs.
A bistable multivibrator is a flipflop, a device capable of storing one bit.
