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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
Connect the two batteries for the voltage needed. If they are 12 volt batteries and the lights are 12 volts, connect the batteries in parallel (negative to negative and positive to positive). If they are 12 volt batteries and the lights are 24 volts, connect the batteries in series (negative of one battery to positive of the other). Run a wire from batteries to first switch, then to two of the lights and the other switch (in parallel). From the second switch run a wire to the third light, then connect all three lights back to the battery.
Where can you find a series circuit?
A lamp A fan and a bunch of other things
AnswerThe classic example of a series circuit is a string of Christmas-tree lights. They are connected in series if, when one lamp burns out, all the lights go out.
How can you measure the resistance?
It is done with an instrument called a megohm meter or megger. On the whole megger testing is non destructive. What happens is a DC voltage is applied to the device or winding under test. It is an insulation test to see is the insulation has been injured in any way to cause a short circuit when normal power is applied to it. On my megger there are 3 ranges 300V, 750V, and 1000 volts. Applying the proper voltage is essential to not damaging the device you are testing. Working voltages up to 240 volts should use the 300 range. Working voltages up to 600 volts use the 750 volt range and working voltages above 600 use the 1000 volt range. As you can see if you used the 1000 volt range on a device that had a working voltage of say 24 volts you could damage the insulation just by testing it. So meggering a device is non destructive if you use the tester as its instructions tell you to.
How did guglielmo marconi wireless radio impact the people and the world?
The radio became one of the number one ways of entertainment and communication in the world. People could finally send their voices across the great waters and other places without wires.
What is the function of emitter bypass capacitor in common emitter amplifier?
The emitter bypass capacitor in a common emitter amplifier will have less resistance as the frequency increases. Since gain in this configuration is collector resistance divided by emitter resistance (within limits of hFe), the gain will thus increase for higher frequencies, making this into a high pass filter.
What is the phase relationship between the input and output voltage of a common emitter amplifier?
In common emitter amplifier circuit, input and output voltage are out of phase. When input voltage is increased then ib is increased, ic also increases so voltage drop across Rc is increased. However, increase in voltage across RC is in opposite sense. So, the phase difference between the input and the output voltages is 180 degrees.
What are the main causes of electrical transformer failures?
The following faults occur in transformer.
1. Temperature rise in winding
2. Temperature rise in oil
3. Overload
4. Insulation failure in oil
5. Earth fault
6. Short circuit
7. Failure of tap changing.
8. Open circuit
What happens when voltmeter is connected in parallel?
An ideal voltmeter has infinite impedance(resistance). If you were to break the circuit and put it in series and try to make a measurement, it is easy to see that the circuit would act completely differently and your measurement would be wrong. An ideal ammeter is always connected in series because it has 0 resistance, so all of the current would flow through it, and not through the wire that you are trying to measure the current of.
A better answer though is to think about what you are trying to measure. When you say something is 3 Volts, that is a difference between the voltages at two different points. If you want to see what the voltage drop across a resistor is, for example, you need to put one probe of the voltmeter on one side of the resistor and the other probe on the other side of the resistor. That setup is simply called being in parallel.
Voltage is potential difference between two points, hence measured across or in parallel, where as current is measured in series since current flows (*)
Why moving iron or hot wire types meters can be used for measuring both AC and DC quantites?
Hot Wire
hot wire is a resistive device ir drop is the same regardless of frequency
hot wire can measure power true power regardless of frequency or phase angle
two wires for power current and voltage both to convert to a measured temperature integration speed depending on the mass of the wire(s)
hot wire can be a bimetal spiral connected directly to the pointer on the scale
Moving Iron:
the moving iron has a spring connected to an iron bar in a coil
dc or ac will cause the iron to be magnetized the amount of current will increase the deflection
normal 50hz 60hz and dc differences are very small
the iron will have induced eddy currents causing higher frequency to have less deflection 400hz on airplanes for lighter transformers... need a different calibration
see "Wigginton voltage tester" simplest moving iron i know of
one moving part, the iron
well 2 if you count the little compass on top to tell dc polarity
large solid core so different for 60Hz then dc by perhaps 10%
How can you tell if a battery still has power?
There are a couple of ways to look at a battery and give it a "test" to see how good it is. One is to measure the voltage, which is a static test. This in not the most definitive way to check out a battery, but it can give some indication as to how much energy is left in the battery. The "proper" voltage that a battery has will creep down as it is used, and then fall off quite dramatically near the end of its usefulness. For example, if you see a battery that should have 1.5 volts across it and it reads 1.1 volts, most of the energy in the battery has been drawn off. The second way to test a battery is the load test, which is a dynamic (and more "real") test. If we use a battery tester, which is simply a resistive load with a "scale" on it, we can get a better idea of how much energy remains in the battery. The little units basically look at how much the voltage "sags" or "drops" when we apply a load. The scale gives some indication as to the remaining energy reserve based on that test. The more the voltage drops when the battery is loaded and asked to deliver current, the less energy that remains in it.
Basic construction of zener diode?
A zener diode has a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is "clamped" to a known value, called the zener voltage.
Why transformer action takes place in a DC circuit?
A: A transformer is a PASSIVE ac component applying dc to it the wires resistance would be the only limiter for current flow. Usually a common transformer will burn up fast or slowly depends on power applied
The power in a resistor (in watts) is simply the product of the current (in amperes) times the voltage (in volts).
The power in a resistor (in watts) is simply the product of the current (in amperes) times the voltage (in volts).
The power in a resistor (in watts) is simply the product of the current (in amperes) times the voltage (in volts).
The power in a resistor (in watts) is simply the product of the current (in amperes) times the voltage (in volts).
What is a circuit with more than one path to flow?
All the branch circuits in your house are parallel. They have a constant voltage applied to any device plugged into an outlet. If you thought about an analogy for a parallel circuit, imagine that the rails on each side of rungs represented the hot and neutral wires of a typical household branch circuit. The rungs would be the loads connected in parallel. Each "load" draws the current needed to operate the specific device. The sum of all the currents for the "loads" is equal to the total current being supplied through the circuit.
Can 4 ohm speakers cause an 8 ohm amp to fail?
The amplifier will have an output impedance of around 0.04 ohms. In hi-fi we have always impedance bridging. Zout << Zin. That means the output impedance of the amplifier is much less than the input impedance of the loud speaker.
The damping factor Df = Zin / Zout tells you what Zout is.
Zout = Zin/Df.
If the damping factor Df = 200 and the loudspeaker impedance is Zin = 8 ohms, the output impedance of the amplifier is Zout = 8 / 200 = 0.04 ohms.
You see, there is no "8 ohm amplifier" on the market with a 8 ohm output impedance.
Scroll down to related links and look at "Voltage Bridging or impedance bridging - Zout < Zin".
Answer #3Actually, it's not a myth. Just a simple misunderstanding. An "8 ohm" amp does not mean it has an 8 ohm output impedance, it means the amp is designed to drive an 8 ohm load. Let me explain (warning, this is long, with math!).Let's say I want to design an amp to provide 50 watts RMS into an eight ohm load with an input of 0dbv (which is 0.775VRMS).
How much voltage and current will I need to produce 50 watts? According to Ohm's Law, P=I^2R, so:
50watts=I^2 X 8ohms
I^2 = 50 / 8 = 6.25
I = sqrt 6.25 = 2.5
We will need 2.5 amps current capacity. Now that we know amps, let's figure volts. E=IR, so:
E = 2.5 X 8 = 20
We will need 20 volts RMS.
Now, how about voltage gain? Our output is 20V, our input is 0.775V, so the necessary gain is:
20 / 0.775 = 25.8
As you can see, this amp will need to supply 2.5A and 20V with a voltage gain of about 26. The design engineer will have to build the power supply with enough voltage to reach 20V at the output, and use output transistors capable of 2.5A.
I won't write out the calculations for a 4 ohm amp, you can do them yourself just like I did above, substituting 4 for 8. If you do, you will find the amp designed for a 4 ohm load will need to supply about 3.5A and 14V, with a voltage gain of 18. Note the voltage is lower, but the current is higher!
If I design this amp for a 4 ohm load, I will need bigger output transistors (3.5A vs 2.5A), but can get away with a lower voltage power supply (14V vs 20V).
See how the design is VERY dependant on which speaker impedance I intend on driving? Now lets see the ramifications of using the "wrong" speaker on an amp.
First, let's put an 8 ohm speaker on an amp designed for a 4 ohm load. We already know from our design calcs above that the amp will be designed to supply 14V. This is less than the 20V needed to drive the 8 ohm speaker to 50 watts, so it is obvious we will not reach full power. We will only get (I = E / R) 14/8 = 1.75 amps, and therefore (P = E I) 14 X 1.75 = 24.5 watts output.
So, if we put an 8 ohm speaker on an amp designed to drive an 4 ohm load, we will get less power, in this case about half. If we try to compensate by turning up the gain or increasing the input signal, the signal will clip and distort because the power supply can't reach the required output voltage. Note that no damage occurs to the amp (although some speakers can be damaged by driving them with a clipped signal), and the setup will sound fine as long as we keep the volume low enough so that our power is less than 24.5 watts.
Ah, but what about the reverse, putting a 4 ohm speaker on an amp designed for an 8 ohm load?
Let's do this: first install a correct 8 ohm speaker on the amp, feed an audio signal in, and adjust the gain so that 50 watts is produced. We already know from our calcs that at this point the amp will be producing 20V at about 2.5A.
Now, remove the 8 ohm speaker and without changing anything else, install a 4 ohm speaker. What happens? Well, if you feed a 4 ohm speaker with 20V, what is the current drawn? I = E / R, so:
I = 20 / 4 = 5A
Oops, this is a problem. The speaker will try to draw 5A, but our output transistors are designed for only 2.5A, I see smoke!
What is the power at this level? P = I^2 R, so:
P = 5^2 X 4 = 100
Oh, another problem. Our power supply is designed for 50 watts, but we are now supplying 100! More smoke.
Now, what if we turn the gain down until the current drops to 2.5A? well, at least no more smoke, since we are no longer overloading the amp beyond it's rated limit. What will the power output be? P = I^2 R, so:
P = 2.5^2 X 4 = 25
Again, if we turn down the gain such that 25 watts or less are delivered, everything will be fine, but if we try to drive the speaker to 50 watts, we may overload the output transistors. And since this amp has higher gain (26 vs 18), and it has a higher voltage power supply, we can drive the speaker to power levels approaching 100 watts, which will certainly pop the output transistors, probably burn up the power supply, and most likely ruin the speaker too.
So, answer #1 is correct. (Yes, I am a design engineer. And, yes, I wrote answer #1...)
Answer #2 is correct as well. An 8 ohm amp does not have an output impedance of 8 ohms. It is indeed much lower. But the question asker meant an amp designed for 8 ohm speakers when he asked the question, and these definitely do exist. And using a 4 ohm speaker on such an amp can cause it to fail. Ask me how I know this... I am no stranger to smoke, believe me.
Answer #4
According to legend and conventional wisdom, solid state (transistor) amplifiers can drive higher impedances than their rating demands. So a transistor amp with a label saying "4-ohm" will drive 4, 8, and 16 ohms with no troubles. You can go up but not down. Don't try 2 ohms.
Older legends say that tube amplifiers can drive lower impedances than their rating demands. So a tube amp with a label saying "8-ohm" may drive 4 and 8 ohms. You can go down but not up. Don't try 16 ohms. And never run a tube amplifier without speakers attached. Other legends of the tube age say that any attempt to use a tube amp with speakers of different impedance may cause damage to the amplifier.
What is the breakdown voltage of PN junction diode?
A Zener diode doesn't allow almost any current to flow below a certain voltage. Above this voltage (the breakdown voltage), the amount of current that can flow is almost unlimited; meaning that the device acts as an "open" for lower voltages, and as a "short" for higher voltages.
Why transistor is used as an amplifier?
A transistor acts like a valve or gate that opens and closes, and allows a current to flow. Since the amount of current that flows is controlled by another input, they can be used to make amplifiers. Carbon microphones and vacuum tubes have the same property, and so have also been used to make amplifiers historically.
What are the advantages of programmable logic controller?
1. Because it is a new technology, so that should require training.
2. Some applications that perform a single function, is not efficient in the use of PLC.
3. Limited usage environments, high temperatures and harsh vibrations can disrupt electronic equipment on the PLC.
4. Need extra security equipment such as really.
5. PLC is not considered necessary when applied to industrial systems that do not need to change the wiring.
Using Ohm's law what is the formula to find amperage in a circuit?
Take your circuit voltage and the power of the appliances and divide.E is voltage I is amperage and P is power or wattage. P=ExI Example. 3500 watt heater draws ? Amps on 220Volts I=P/E I= 3500w/220v I= 15.9Amps
In general, electrical circuits refer to the pathways or routes that are used to deliver electric power onto the power grid and out to the site where a customer actually uses it. It's possible to say the electric power grid is a large electrical circuit. It is. We can use terms like wire or lines or conductors when we talk about the power grid. You already know that there are transformers, circuit breakers (disconnects), fuses and other "stuff" in the circuits. An electrical circuit could be any subsystem of the larger whole. The electrical circuits in a residential structure could be all the wiring from the meter and breaker panel to all locations in the home. The electrical circuits of your home can be described this way. An electrical circuit could be a subsystem of a piece of equipment that helps an observer differentiate it from another subsystem. In a TV, for example, the video circuits are electrical circuits that are separate from the audio circuits. Each is a distince electrical circuit in this light, and someone like, say, a repair technician will be looking in the audio circuits to see why your TV has no sound rather than in the video section. The two electrical circuits are distinct in this light. We could go on, but this may cover the basics acceptably.
What is a barometer and voltmeter used for?
A barometer measures the barometric pressure of the atmosphere. Units of millibars. That is one-thousanth of a bar. 0.001 bar equals a millibar.
A voltmeter measures electricities potential to do work measured in volts A.C. and D.C.. Most can also measure resistance in ohms and current in amps. Some can measure frequency (hertz= cycles per second) and capacitance in farads.
CommentIn SI, barometric pressure is measured in pascals (Pa).
Can an optical fiber transmit microwaves?
To be perfectly technical, the answer to this question would have to be 'yes', but
only because light and radio are the same physical phenomenon.
The optical fiber only conducts the electromagnetic waves that we usually describe as "light".
The waves that we normally describe as "radio" cannot pass through optical fiber.
What is the lumen output for a 50W halogen?
Halogen lamps run hotter than conventional incandescents, and as a result of their hotter filaments, emit a whiter light with more of the light in the visible range, and less in the infrared. A typical 50W halogen emits between 800 and 950 lumens.
In contrast, a fluorescent lamp produces more of its output as light instead of heat. Therefore a 13W compact fluorescent light emits the same number of lumens, while an 11-13W LED lamp emits the same 800 lumens (though this is rapidly improving)
