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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
What are the effects on the voltmeter if voltages measured exceed the range?
If the voltage measured exceeds the voltmeter range then the voltmeter needle remains in it's maximum position until it's voltage values are considerably reduced.
Difference between diac and triac?
The diac and the triac are used to control the AC lines. The difference is that triac are bigger than diac.
This allows the 3G3MV increased intelligence and autonomy for tasks such as positioning and synchronization. Combining the inverter and PLC eliminates the cost and delay of point-to-point wiring, while saving panel space. The onboard PLC features RS-232 and the vendor’s hostlink communication. A direct, dual-port RAM connection gives complete access to inverter parameters, as well as providing encoder input, interrupt inputs, and digital, pulse and PWM outputs, resulting in enhanced speed, positioning and function control for the application being controlled. See More industrialstorebd
R = E / I
= (50 x 106) / (50)
= 1 megohm.
Strange for a "shunt". Must be across one heck of a meter movement !
It looks like the question was misworded. Instead of 50 megavolts, perhaps it should have been 50 millivolts. In that case the meter/shunt impedance would have been 0.001 ohms. In any case, the actual value of the shunt resistor would depend on the impedance of the meter itself. In the latter (assumed) case, this is probably negligible, so the shunt does appear to be 0.001 ohms.
Is the Close Door function on an elevator useless?
It turns out that the vast majority of functioning close-door buttons on elevators became obsolete as a result of the Americans With Disabilities Act of 1990, which required that elevator doors remain open for a minimum of three seconds, or long enough for anyone with a wheelchair, cane, etc. to safely get on board. The only exception to the rule is if a firefighter manually overrides the door function with a key.
Karen W. Penafiel, the executive director of the National Elevator Industry, Inc., confirmed in an interview with The New York Times that by pushing the button, "the riding public would not be able to make those doors close any faster." However, this hasn’t prevented manufacturers from continuing to install them in order to give the public a false sense of control.
Another example of this type of "mechanical placebo," as it's called, includes pedestrian crosswalk buttons that were deactivated with the rise of computer-controlled traffic signals.
Difference between ofdm dsss fhss?
Orthogonal Frequency Division Multiplexing (OFDM) is a multiple-carrier (MC) modulation technique which creates frequency diversity. A high-speed data stream is converted into multiple low-speed data streams via Serial-to-Parallel (S/P) conversion. Each data stream is modulated by a subcarrier. That way, instead of having a frequency-selective fading wireless channel, where each frequency component of the signal is attenuated and phase-shifted in different amount, we have multiple flat-fading subchannels. In other words, instead of having a signal with symbol duration smaller than the channel delay (remember that high frequency means low duration because f = 1/T), we have may subsignals with duration larger than the channel delay (to simplify things, consider this: if the symbol duration is 1 s and the channel delay is 10 s, we will have interference between 10 symbols). That way, channel distortion is compensated. The OFDM symbol is the composite signal formed by the sum of the subcarriers, so the data rate is still the same as if we transmit the original high-speed signal, but as we said, the channel distortion is compensated. OFDM compensates the Inter-Symbol Interference (ISI) caused by the fact that different signals take different paths and arrive at the receiver with different delay (multipaht propagation distortion). OFDM subchannels are not separated by a guard band, but they overlap. However, they are orthogonal at the subcarrier frequencies, and that way they don't interfere with each other. We have very good utilization of the available bandwidth due to the overlapping of the subchannels. Moreover, each subcarrier can be modulated seperatelly (usually, QAM or QPSK modulation is used, depending on the channel conditions, which are measuer using channel estimation via pilot carriers). Also, we can use adaptive modulation and conding (AMC) at each subchannel in order to accomplish error-free communication with the highest data-rate possible. Due to the orthogonality principle, we don't need a bank of modulators at the transmiter and a bank of demodulators/detectors at the receiver, but simply a chip implementing the Inverse Discete Fourier Transform (IDFT) and the DFT respectively - and that can be done easy, effectively and with low-cost using a chip running the Fast Fourier Transform (FFT) algorithm. Timing errors/phase distortion must be controlled because they may create ISI between OFDM symbols and ICI (Inter-Carrier Interference) between subcarriers. We add a Cyclic Prefix (CP) to avoid ISI between OFDM symbols and synchronization methods to avoid ICI. Also, the inherent Peak-to-Average Power Ratio (PAPR) of the OFDM signal must be reduced because forces the power amplifier of the transmitter to operate on the non-linear region of its characteristic function.
Spread Spectrum (SS) techniques convert a low-speed data stream into a high-speed data stream. That way, the bandwidth of the modulated carrier becomes much larger than the minimum required transmission bandwidth. This is like Frequency Modulation (FM): we trade transmission bandwidth with Signal-to-Noise (S/N) ratio, meaning that we can have error-free communication transmiting lower-power signals. The signal is spreaded in a huge bandwidth. That way, instead of having the noise (which is like an interference signal) concetrated to some symbols and corrupting the signal, the noise is uniformly distributed over the signal bandwidth. Moreover, the signal is not easilly detectable by a third-party because it is hided in the background noise. Finally, it has anti-jamming characteristics. There are two techniques to create a SS signal: Direct-Sequence Spread Spectrum (DSSS) multiplies the data stream with a high-data rate sequence called chip sequence or Pseudo-Noise (PN) sequence, because due to its lenght is seems as a random signal, like the noise (but of course, it is a completely deterministic signal; that's why we use the Greek term "Pseudo-", which means "it appears to be, but it is not"). DSSS creates time diversity (a "variety" in the time domain). Frequency-Hopping Spread Specturm (FHSS) uses a chip sequence to conrol the frequency hops of the carrier. The resulting signal is like a progressive-FM signal. FHSS creates frequency diversity (a "variety" in the frequency domain). SS techniques give a Spreading Gain (SG) to the transmitted signal, which is simillar to the Coding Gain (CG) of the error-control codes [remember: in Forward-Error Correction (FEC) techniques, we add additional bits to correct errors; we use this rendudancy for error control. That is, we increase the transmitted bandwidth but we can decrease the transmitted power required to have an acceptable S/N at the receiver). Moreover, SS techniques can be combined with multiple access techniques (patterns for multiple users access a network by sharing the common channel). With Code Division Multiple Access (CDMA) a code sequence is used to give an identity to each user, which than we will transmit a signal spreaded by a PN sequence. So, each user can use the whole available bandwidth for all the time, but users do not interfere because they are separated in the code domain. The orthogonality of the codes (of the signals) must be maintained, because otherwise we will have interference between the users. Finally, a RAKE receiver can be used to resolve the multiple paths and compensated the ISI caused due to the multipath propagation.
OFDM and SS techniques can be combined (MC-CDMA). OFDM can also be combined with the Frequency Division Multiple Access (FDMA) -> OFDMA. Finally, OFDM can be combined with Multiple Input-Multiple Output (MIMO) techniques. In MIMO, we have multiple transmiting and receiving antennas. So, we have N parallel channels instead of a single channel, and this creates a signal which is N times faster (oversimplified, but basically true ...). In each channel we can use OFDM to avoid ISI and frequency-selectivity, while maintaining the high-data rate. Finally, MIMO can create diversity which enables the system to receive the best-quality signal.
What is the difference between electronic and mechanical?
An electronic stopwatch gives a higher accuracy than a mechanical stop watch.
Triac
Your 11 kv to 220 volts represents a 50 to 1 stepdown. (There is 50 times more voltage in the primary than in the secondary.) You'll have to have a 50 to 1 turns ratio. That means 1/50 of the number of turns in the primary will be in the secondary, and that is 64 turns.
Application Specific Integrated Circuits.They Are used to serve a specific purpose for example the motherboard of your computer
R = E/I = (12)/(0.1) = 120 ohms
(Make it a big one. It dissipates I2R = 0.01 x 120 = 1.2 watts.)
What are the differences between sinusoidal oscillators and non sinusoidal oscillators?
sinusoidal vs non sinusoidal
As long as you don't exceed the breakdown voltage of the capacitor ... which is marked right on it ... DC voltage on it produces NO current flow through it. Only AC 'appears' to flow through a capacitor, and even that appearance is bogus when you really get down to it.
What materials are used to make the iPad?
Aluminum, Glass, Plastic, Steel, Copper, Silicon, Gold, Nickel, Silver and other trace elements.
I think this is in the wrong section but I'll answer it anyway, a ripple edit in Premiere Pro or something is when you want to edit a clip that is in between 2 clips it realigns all the other clips and keeps them all at the same distances as they were before from the end of the piece you moved.
MediaCollege.com says,
A ripple edit means moving an edit point and causing the rest of the timeline to move the same amount to compensate.
What is the purpose of control panel?
to allow users to view and manipulate basic system settings and controls
Interesting question. Because Fleming's right hand rule tells us that a conductor carrying a current perpedicular to a magnetic field will move in a particular direction we know that movement, current and magnetic field are related. So if we take the current away and instead force the conductor to move as described then we would observe a current in the wire. However, you have not said that your conductor is connected in a circuit - in which case the charge carriers in the conductor will tend to one side like a bar magnet.
Answer
The original answer is incorrect. A voltage would be induced into the conductor. No current would flow unless the conductor forms a continuous circuit.
Why FDM is for analog signals and TDM is for digital signals?
FDM stnds for frequency division multiplexing and it is used only in case of analog signals because analog signals are continuous in nature and the signal have frequency.
TDM-stands for time division multiplexing and it is used only in case of digital signals because digital signals are discrete in nature and are in the form of 0 and 1s. and are time dependent.
What is the advantages and disadvantages of on the job training?
I dont know the answers. please help me
a transducer which can measures a physical quantities and and transmit the informations as coded digital signalsrather then as continuous varying current/ voltage.
