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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
How does a phototransistor work?
All bipolar transistors are light sensitive: photons striking the semiconductor create electron-hole pairs which make the transistor conduct.
In ordinary transistors this is an undesirable source of noise, so they are packaged in opaque metal or plastic cases.
A phototransistor on the other hand is packaged either in a metal case with a transparent lens or in transparent plastic to let light in.
Note: this is not a significant effect with MOS transistors.
3 kilo ohms times 3 micro ohms equals?
You have to convert all values to ohms.
3 kiloohms = 3000 ohms.
3 micoohms = three millionth of an ohm = 0.000003 ohms.
The product is: 3000 times 0.000003 = 0.009 ohms squared.
What is meant by a nominal current?
The word nominal means the lowest possible safe amount. So, nominal current or nominal voltage is the lowest amount necessary to perform an electrical function like keeping a light turned on.
Answer
The original answer is incorrect. 'Nominal' simply means 'named'. So a 'nominal voltage' is the 'named voltage', as opposed to an 'actual voltage'. For example, the nominal voltage of residential supplies in the UK is 230 V; however, this value is allowed to vary between +10/-6% of the nominal voltage. In other words, a nominal voltage of 230 V may vary between 216 V and 253 V.
Why monostable multivibrator called one shot?
They are called one shot because they generate a single output pulse of a specified width either high or low when external trigger is applied.
Can you change 50 v micro farad capacitor with a 63 v 100 microfarad capacitor?
Generally, yes - a 35 uF capacitor is close in value to a 30 uF capacitor - but it depends on the circuit requirements. If you are talking about a tuned filter, I would say no. If you are talking about a power supply filter, I would say yes. Just keep in mind that it takes more current to charge a larger capacitor, so you need to consider the current rating on the diode(s). Of course, if this mattered in a power supply, then I would also say that the design margins are too tight. Again, 35 versus 30 is not a big difference - again, sometimes. Also, you need to ensure that the voltage rating of the new capacitor is equal to or greater than the voltage rating of the old capacitor.
I've received a message that this capacitor is a motor starting capacitor in an air conditioner. My answer is this...
Then I would consider it a tuned circuit, because phase angle of the power in the start windings would matter to the proper starting of the motor. However, my root analysis holds - you need to consider the system's design requirements.
If any motor engineers out there are willing to take a stab at this, please do. I have flagged the question to attempt to get a better answer.
Explian the working of a common-source amplifier and a common drain amplifier?
Configuration
Voltage Gain
Current Gain
Input Resistance
Output Resistance
Common- Source
AV >1
-
∞
Moderate to high
Source-Follower
AV ≈ 1
-
∞
Low
Common- Gate
AV > 1
Ai ≈ 1
Low
Moderate to high
Both the common-gate and common source has voltage gain of greater that 1 compared with the voltage gain of source- follower which is less than or approximately equal to 1 . The input resistance of both common-source and source follower is high typically ranges from kilo ohms and above while common-gate has a low input impedance ranges from hundred ohms or below. The output resistance of both common-gate and common-source are dominated by RD while source follower has low output impedance and is not dominated by RD
A TRIAC is a three terminal device that can operate an AC load, either in On-Off mode, or in modulated mode, such as in a lamp dimmer.
The three terminals are M1, M2, and Gate. The AC source and load are connected in series with M1 and M2. If the Gate is held near the voltage of M1, the device does not turn on. If the Gate voltage is towards the direction of M2, the device turns on. Once the device turns on, it stays on for the duration of that line cycle, i.e. until the voltage between M1 and M2 reverses.
The actual trigger point varies depending on the specific device, so you need to look it up in the specifications for the device.
Note that the positive going trigger point is often not the same magnitude as the negative going trigger point. This can cause asymmetry in the output power, leading to a DC bias that is often not desired. Most designs compensate for this by providing another TRIAC operating in DIAC mode (or just a DIAC) in series with the Gate.
The DIAC is simply a TRIAC with the Gate connected to M2. This mode will trigger based on M2, rather than on Gate, and is symmetrical. Using a DIAC as the trigger for a TRIAC will balance the output waveform, minimizing DC bias.
If you design the controlling circuit so that the trigger point in the cycle is adjustable, you get a variable voltage switch, i.e. dimmer, that can be used for various things. The advantage of this over a rheostat, is that the TRIAC is fully conducting when it is turned on, so the power dissipated by it is relatively small, because the voltage differential is small, whereas a rheostat would need to dissipate at least half the expected power of the load.
What are the advantages of using transistor as an switch instead of diode?
1. A transistor *is* a triode- this is the general name for any three-electrode electronic device.
2. Most people understand "triode" to mean a tride vacuum tube/valve.
3. The transistor
(i) needs no heated filament/cathode, so it uses much less power than a valve triode,
(ii) because of (i), transistors do not "burn out" with age, so they have much longer lifetimes, are much more reliable, and generate much less waste heat,
(iii) transistors can operate at much lower power than triode valves, and at much higher frequencies,
(iv) transistors can be made much smaller than triodes, by a factor of many tens of thousands,
(v) from early on, transistors were much cheaper than triode valves.
An IR LED is used in applcations like remote controls...it's much the same as as a normal Light Emitting Diode...Just that the wavelength of the emitted light is not present in the visible spectrum...
What happen if primary of transformer connected to dc?
Nothing noticeable. DC power is not transmitted between the coils of a transformer. There would be no current on the other side of the transformer, unless the power of the source was constantly modulated. bescause flux does not change its state.
after some time excessive heat is produced and winding may burn
AnswerA transformer's primary winding presents two forms of opposition to current flow. The first is resistance, which is dependent upon the length, cross-sectional area, and resistivity of the wound conductor. The second is reactance, which depends upon the inductance of the winding and the frequency of the supply. Resistance opposes both AC and DC currents, while reactance opposes only AC current. In the case of a transformer's windings, the resistance is relatively low while the reactance is very high. When an AC voltage is applied, the reactance is sufficiently high to limit the value of AC current flowing through the winding. However, the resistance is so low that a large current would flow if an equivalent DC voltage was applied instead. This current would likely overheat the winding's insulation, resulting in its breakdown, causing a short circuit(s) which could severely damage the transformer.
What is the advantage of half wave rectifier over full wave rectifier?
The advantage of a full wave rectifier is that it produces less ripple and the ripple has a higher frequency, making it easier to filter.
The advantage of a half wave rectifier is it is simpler and less expensive as it needs fewer components.
Which is best in a given application however requires making other tradeoffs that are out of scope for this question as they cannot be determined without knowing the details of the specific application. So neither is universally the best.
What is a big circuit board that has smaller circuit boards plugged into it?
the answer is the mother board of the computer
What is the voltage range in low voltage?
In British standard voltage classified Low Voltage( up to 1000 v (1 kv) medium voltage 1001 v to 10000 v ( 1.01 kv to 10.99 kv) High voltage 11kv to 66 kv and Ehv 66.1kv and above.
Can you use a 500mA 12VDC transformer on a unit that requires a 180mA 12VDC?
From your question I assume you are referring to a charging adapter for a piece of electronic equipment. I believe adapters also contain a rectifier that rectifies AC voltage to DC. The one I'm looking at at this moment does this.
Your thinking is correct, in that any thing that transforms the voltage to what you need is all you need for that step. But if your adapter rectifies the voltage you will need a rectifier with your transformer.
How do you design the 3 bit binary counter using D flip flop?
Designing a 3 bit synchronous counter using jk flip flop is not an easy project for the uninformed. This is best left to professionals who are adept at programming. There are lengthy guides available on the internet if it is necessary to create one.
A latching circuit is a circuit with two stable states, which one can think of as 1 and 0, thereby being able to store one bit of information. In circuit diagrams, these are represented by cross-coupled NOR or NAND logic gates.
Why amplitude modulation is used for video transmission?
IF we use frequency modulation for transmitting video signal this can cause phase shifting .and eyes can percieve this distortion effect easly . and requires more bandwidth to send the signal .Color levels are adjusted by amplitude in TV .So it s more logic to use Amplitude modulation .
How many half adder to make full adder?
binary addition of two bits is called a half adder ,and of three bits is called a full adder to be more lucid in my explanation a half adder doesnot consider a carry generated from the previous added pair of binary numbers
consider an example :-
A=a1a2a3a4 + B=b1b2b3b4 = sum=s1s2s3s4
the actual addition procedure is a4 and b4 are added first then the sum is stored in s4 and the generated carry is added with a3 and b3 and the process continues
so addition of a4 and b4 where there is no input carry is carried out by half adder and the addition of c1+a3+b3 is carried out by full adder. but practiclly the first situation a4+b4 can be considered as a4+b4+0 so all the addition can be performed by full adder it self
truth table for both half adder
A B s c
0 0 0 0 0 1 1 0 1 0 1 0
1 1 0 1
for full adder
c1 A B s c
0 0 0 0 0
0 0 1 1 0
0 1 0 1 0
0 1 1 0 1
1 0 0 1 0
1 0 1 0 1
1 1 0 0 1
1 1 1 1 1
where s and c can be viewed as the sum and carry
on solving the k-map for full adder and half adder we can obtain the fuctions of sum and carry
What remains constant in series circuit?
A: No matter how many resistor of different value are inserted the current will remain the same for each. The voltage drop will vary with the difference in resistors and i a parallel path is found along the way the current will divide according to the resistors values
