Questions tagged [phase]

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49
votes
11answers
24k views

Why three-phase power? Why not a higher number of phases?

Is there a reason, beyond historical reasons, that three phases has become the dominant number of phases? I am aware of the advantages against one phase and two phase, namely the reduced amount of ...
32
votes
3answers
11k views

Why 3 phase and not 1 phase power transmission?

Why does power transmission use three lines with three different phases? Why not three lines all in the same phase? Does it have to do with the alternators used for generating the power, or is there ...
20
votes
7answers
5k views

Staying in Phase On The Grid

I have been an EE for over forty years and never did find out the right answer to this one.... How do power-stations and transformer switching stations ensure that the power they are feeding into the ...
11
votes
6answers
3k views

Comparator: Noisy sine to square wave, how much phase noise?

In a circuit a comparator is used to convert a sinusoidal signal to a square wave. The input signal however is not a clean sine wave, but has some noise added to it. The comparator is supposed to be ...
7
votes
2answers
5k views

Why do we use a diac for triggering a triac?

I mean, Wouldn't it be possible to give a gate pulse on triac directly? I have seen in many phase control application circuits like fan speed control,the usage of diacs to trigger a triac.
6
votes
2answers
6k views

Manual transformer winding - dots convention

I've already seen this and this. But I can't decide how to correctly wind a SMPS transformer. This is the transformer: I mantain the same turns direction (CCW if you look at transformer from the top)....
6
votes
1answer
709 views

What does actually the "unravel branch wrap" option do to the phase plot in LTspice?

Below two Bode plots are identical just that in the second one the option "unravel branch wrap" is unticked for the phase plot: What does this option do to the phase plot?
6
votes
2answers
877 views

How is the gain/phase vs frequency measured for opamps?

Opamp manufacturers post graphs like these in datasheets: How is the data for this graph measured? Is it calculated using the mathematical model of an opamp?
5
votes
3answers
545 views

About the torque-free charging operation

I and one of my friends are working on understanding the below context (paper link): The study provides an extensive overview of on-board integrated chargers for electric vehicles that are based on ...
5
votes
4answers
14k views

Can we short the neutral to earth (ground) at entry point of our home electrical supply?

Normally in our 230V power outlet, the voltages are as given below. Neutral to Earth - Less than 2V Neutral to Phase - 200V to 230V Earth to Phase - 200V to 230V But nowadays, after around 10 am, ...
5
votes
1answer
60k views

How to find phase angle from transfer function

From the function: $$H(\omega) = \frac{1}{(1 + j\omega)(1 + j\omega/10)}$$ How is the phase angle obtained when it has multiple poles to get: $$\phi = -\tan^{-1}(\omega) - \tan^{-1}(\omega/10)$$ ...
5
votes
1answer
169 views

Find the phase angle between two functions

Apologies if this is better suited for a mathematics forum, it's from my circuits textbook so I've decided to post here. Below is a practice problem from the textbook, with the provided solution. If ...
5
votes
2answers
2k views

Amplitude noise vs Phase noise

I've been reading that Phase Noise dominates in frequencies close to the carrier, while Amplitude Noise is more dominant in higher offsets. Could someone explain this?
4
votes
2answers
209 views

Finding phase shift between the voltage and current

I am trying to find the phase shift \$\phi\$ of this circuit. I am using the formula: $$\phi = arctan{\frac{X_{L}-X_{C}}{R}}$$ Substituting in the values: $$\phi = \arctan{\frac{2000\Omega-4000\...
4
votes
2answers
389 views

How to measure phase accurately using LTSpice?

I am trying, and failing, to measure phase in LTSpice. I've used the suggestion here ...
4
votes
2answers
155 views

Why do crystals have 0° phase shift at series resonance?

I am trying to understand the inner workings of crystal oscillators, but I do not understand why the current has 0° phase shift at series resonance. To my knowledge this is the equivalent circuit for ...
4
votes
1answer
747 views

How can I create two ac signals with a voltage controlled phase offset?

Is there a fairly straightforward analog circuit (resistors, capacitors, transistors, etc) to generate two sine waves of the same frequency and introduce a relative phase offset between them? So I'm ...
3
votes
3answers
4k views

240V split phase and 240V single phase

All right, I don't get it. I tried and tried, but I just don't understand. I have a dozen questions about this so somebody just pick one out all of these, I don't care. What's inside a North American ...
3
votes
5answers
6k views

Run heater on two powerlines, where the second line is switched according to the main line

I got a water heater which is rated 6kW. The "heating element" consists of 3 heating elements that are connected in series for 1-phase usage. I would like to run two of those heating elements on one ...
3
votes
3answers
3k views

Detect Phase Difference 360 Degrees

Let's say I have two sine waves that are both DC offset to have no negative values, the measurement I want is the phase difference between these waves. When researching I've only seen detectors that ...
3
votes
3answers
2k views

Circuit To Measure Phase difference

Is there any classical analog circuit to measure the phase difference between two analog signals ( especially sinusoidal signals )? I want to measure the phase difference between two sinusoid signals ...
3
votes
2answers
1k views

Snubber Circuit working

How does snubber circuit work in phase control circuit of Single Phase AC Motor? I have tried to know the causes but I was confused with RC circuit function with this phase control circuit.
3
votes
1answer
54 views

Suitability of standard-gain pyramidal horn for UWB signal

Objective I'm interested in evaluating the suitability of a standard-gain pyramidal horn for an ultrawideband (UWB) signal. However, I've had difficulty finding reliable information about the phase ...
3
votes
2answers
549 views

Does guitar pickup absolute polarity matter?

I have a Telecaster which has a phase issue in the middle position, because the bridge pickup is wired backwards (the hot output to the ground). This hot grounded output is also used to ground the ...
3
votes
1answer
146 views

How are phase values able to capture motion from video?

I know that the phase spectrum contains most of the structural information about the image. But I want to know more about importance of phase spectrum related to video signals. I have read that ...
3
votes
1answer
64 views

Phase relationship of multiple Fractional-N PLLs with same reference clock

I think I understand the general operation of PLLs in the case where a single reference clock generates a single output clock. Once the PLL is locked, there is a deterministic relationship between the ...
3
votes
3answers
898 views

Approximation of a Non Ideal Differentiator

simulate this circuit – Schematic created using CircuitLab The above circuit is a differentiator, the op amp is assumed to be a single pole op amp, that is \$ A=\frac{wt}{s}\$ The transfer ...
3
votes
1answer
2k views

Can I use any capacitor for a 2 phase AC motor?

So recently I got my hands on an old pump motor, unfortunately the connection diagram is missing. I have already determined this is a 2 phase motor, and that in order to make it work I need a motor-...
3
votes
1answer
183 views

Triangulation with Single Tone FM TX and Three RX using Phase Detection [closed]

I'm looking for some IC and frequency suggestions to accomplish the following task. Modulate a tone onto a carrier and continuously broadcast this signal toward an array of three receiving antennas(...
3
votes
1answer
54 views

Whether phase congruency and phase coherence terms are same or different?

I am studying the importance of phase in signal.Can anybody explain what is phase congruency ? Also,I am confused between terms i.e. phase congruency and phase coherence. Whether phase congruency and ...
3
votes
2answers
2k views

Understanding Phase frequency detector logic

I have one of these common digital phase lock loops which compares the frequency and phase with a VCO (local oscillator) via a phase lock loop. I failed to understand why Figure (2) (A) and Figure (2)(...
2
votes
1answer
172 views

About power dissipation of capacitors and inductors & I-V phase difference

For instance, The Art of Electronics (by Horowitz & Hill) states that ideal capacitors cannot dissipate power, even though current can flow through them, because the voltage and current are 90° ...
2
votes
3answers
297 views

The distribution of phase angle between identical zero mean Gaussian random signals?

I am trying to solve the 2013 paper set by ISRO for electrical engineers. I was hoping to get some clues on how to approach this problem - No 22. random signals which have gaussian distributions will ...
2
votes
2answers
1k views

Make FTDI 2232D do SPI mode 1 properly? Data seems 1/2 clock cycle off

This capture by a Saleae Logic Pro 8 (v 1.2.18) shows the result of transmitting (MOSI data) 0x20 0x11. Unfortunately it is interpreted and shown as ...
2
votes
2answers
1k views

Is group delay the same as the delay of a certain frequency?

I know that group delay is the delay of the envelope, or the derivative of the phase with respect to \$\omega\$. What I want to know is what exactly happens in the time domain. For instance take the ...
2
votes
4answers
3k views

BLDC max speed KV or Hz?

So from what I've understood, the KV rating for a motor gives us the rotor speed based on the voltage applied at the phase of the motor. Having looked a bit deeper in ESC / inverters, I've come up ...
2
votes
3answers
744 views

Linear Phase Response

In many cases, it is demanded that filters have a linear phase response (like in the case of FIR). Why is linearity so important? Why not a constant phase response, or anything else (any other shape)...
2
votes
3answers
72 views

Magnitude calculation of filter

I am working on a problem for a given transfer function given below and am having trouble calculating the magnitude and phase of it. The problem is specifically that I do not know what method to use ...
2
votes
2answers
2k views

Why does the tank circuit of Coplitts oscillator produce 180 phase shift?

http://www.circuitstoday.com/colpitts-oscillator I would like to understand how Coplitts oscillator works. This link says that the tank circuit of Coplitts oscillator produces 180 degrees phase shift....
2
votes
2answers
1k views

Phase Shifter: why is simple RC circuit's output 0 when phase is 90 deg?

I am rereading an electronics book (Fundamentals of Electric Circuits; Alexander) that says that the circuits or have the total impedance Z = R + jXc and that the phase shift is given by ...
2
votes
2answers
395 views

How do I find the -3dB point on a given graph

I just performed an AC Simulation on QUCS and was asked to find values of gain and phase at low freq. and high freq and at the -3dB frequency point with the roll-off slope. The circuit is an RC ...
2
votes
2answers
110 views

Power to the home in the UK

We have a question about the power available to the home in the UK. Our product draws a fair amount of current, so we have (so far) designed it to be powered by ~230vac single phase at 48A OR ~230vac ...
2
votes
1answer
1k views

Microstepping methods for stepper motors: PWM? Phase? Frequency?

I want to know what methods are used for microstepping stepper motors, and their pro's and cons For example, I presume, to hold the motor between two steps, PWM would be most efficient; simple ...
2
votes
1answer
438 views

Why do four cascaded all-pass filters cause a 180° phase shift?

This op-amp all-pass filter is reported to introduce a 90° phase shift at the cutoff frequency of the RC network placed at the + input. (The FET is used as a controlled variable resistor to move the ...
2
votes
1answer
3k views

How to find stepper motor's rated current to set current limit?

I am trying to set the current limit on a NEMA 17 stepper motor. I found a tutorial but it's asking about the current rating. From my stepper motor datasheet, the only information related to current ...
2
votes
2answers
99 views

Understanding Working of High-Pass RC Filter

I was trying to visualize what happens when frequency is swept from 1Hz to 1GHz. In case of capacitor, voltage lags behind current by 90 degree and capacitor reactance depends upon it's frequency. I ...
2
votes
2answers
237 views

Phase difference between resistor and inductor voltage in an RL AC circuit

In my textbook, it is given that \$\mathcal {E} = -L\frac{\Delta I}{\Delta t}\$. The graph of resistor voltage (\$V_R\$) and inductor voltage (\$V_L\$) in a series RL AC circuit is given similar to ...
2
votes
1answer
2k views

Can a phase margin become bigger than 180° and is this bad?

I have a wrong mental model about phase margin in control theory. I see that a phase of -180° is bad. If my input is a sine wave and I have negative feedback, which has a -180° phase shift, the ...
2
votes
1answer
304 views

Odd voltage readings between phase-ground, phase-neutral, neutral-ground

Recently i tried gathering voltages from few AC outlets in my house. I got following readings using a dmm Phase-Ground = 398V-400V (should be around 240V) Phase-Neutral = 230 V Neutral-Ground= 210 V ...
2
votes
2answers
164 views

Phase-sensitive-detector

I'm working on a phase-sensitive-detector that uses an FPGA for signal processing.For an input of a pure sinusoid with known frequency and in the range of 1 Vrms, I need to find the phase of the input ...

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