# Questions tagged [phase]

For questions about AC phases (e.g. three-phase systems) or phase in the context of waves, transfer functions, etc. Consider using in conjunction with related tags such as "three-phase", "transfer-function", etc., as applicable.

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### 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 ...
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1 vote
1k views

### Run 1800 RPM motor at 3600 RPM

I have a 2”x72” belt grinder with a Brook Crompton bf4n.75-2 motor. It is connected to a Teco L510 VFD. Running here in the United States on 110v. My question is about turning up the RPMs sometimes ...
569 views

### Link between phase noise and linewidth for a oscillator?

I was googling for a formula to transform the dbc/Hz value given in data sheets for VNA, spectrum analyzers and VCO is often given in dBc/Hz with offset. Now looking up research papers about future ...
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### Philicorda phase shifter vibrato circuit doesnt work

I have built this circuit in the online editor, but it doesn't seem to oscillate. My philicorda vibrato broke down and i want to repair it. It should convert 21V DC into a sine wave when i understand ...
2k views

### Calculate Angle for Triac Phase Control

Triac-based phase control of the mains power into resistive load. According to this post, https://www.physicsforums.com/threads/how-to-calculate-rms-voltage-from-triac-phase-angle.572668/#post-...
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### Pulse skip modulation vs Phase cutting for AC inductive loads?

What is preferred and safe mode for controlling power to an Inductive AC load when driven by a Triac? I am using a microcontroller with zero crossing optocoupler to drive the control signal and the ...
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### What is phase ripple and how is it measured?

Whilst reading up on phase response, I came across a reference to "phase ripple". Specifically, I was reading this article by Keysight, on phase measurements. From my understanding of the article, ...
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### In a three phase choke, is the rated current per phase or for all 3 together?

In a 3-phase choke, for example here: https://katalog.we-online.de/pbs/datasheet/744839010400.pdf What is the current rating? For the inductance it says 3x10.5mH, so its 10.5mH in each phase and if I ...
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### During the positive cycle of US AC MAINS Electricity is the secondary Voltage back EMF or in phase with the AC MAINS?

The Sine wave of AC Mains in the US starts at zero and increases to Vmax~169-Volts. in the beginning magnetic Flux Change is greatest as it is proportional to the slope of the AC Sine wave (which is ...
951 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?
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### high side mosfet offset voltage in Phase shifted full bridge converter

I am working on phase shifted full bridge converter. The input voltage of it is 300 V. The issue is I am able to see offset voltage (shown in fig below) in the gate to source pulses during turn-off ...
358 views

### Matlab Three Phase System Model

I have a question regarding MATLAB Simulink if anyone is familiar with the software. I usually have no problems creating basic models like this one below: I know the image is rather small. It is ...
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### Hook up an automatic transfer switch with two phases only

We have a house in Haiti connected to the shore line. The shore line isn't always working so we bought a generator. I wanted to ground one of the two phases to create one neutral, one phase and a ...
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### Bode Phase Plot of RC High-Pass Filter

I have been trying to understand Bode Phase Plot of RC High pass filter. I know that from my engineering that voltage lags behind the current passing through the ...
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### Is there an analog circuit or filter that can produce constant phase shift over a specific bandwidth?

I need to match the phase of two signals coming from a pair of transducers over the 10Hz to 4 KHz range, the difference between the two transducers is really close, however one of the transducer lags ...
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### what would be the function of a resistor 36,000 ohms across leads on non polarized electrolytic capacitors in a roto phase phase converter

I have a surface grinder (3 phase) and believe that some of the capacitors are shot in my phase converter due to a lack of available surge power. The grinder starts and works ok but the circuit board ...
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### Impedance magnitude and phase error - Mathematical formula

Today I read a paper on which there are the terms magnitude error and phase error relative to a comparison between measurements performed with a biosensor and with a benchtop electrochemical impedance ...
181 views

### Physical significance of positive group delay with negative phase delay

This question is an addendum to: Is group delay the same as the delay of a certain frequency? Lately, I've been going back to basics to better understand the concepts of group and phase delay, so I ...
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581 views

### PA92 OPAMP phase compensation

I'm having trouble to understand the phase compensation on the PA92 opamp. First I'll explain quickly the circuit I'm building.   1.  The circuit I'm using a 200V battery and would like ...
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### 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 ...
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### noobie question on 3 phase [closed]

i am renovating a house and the electrician has installed all new wiring ,circuit switches, outlets etc... so now the electric company has asked if i want 1 or 3 phase. I told them 3 phase and ...
363 views

### IEEE 1588 PTP phase and time synchronization

Why everywhere is said that PTP synchronize phase and time together? phase and time are totally separate concepts. does it mean after using PTP rising edge of slave and master clocks happen ...
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### 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 ...
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758 views

### Calculating Phase/Time Delay induced by a 2-pole Bandpass filter? ie. Group Delay?

If you have a two-pole Butterworth bandpass filter described by a particular Q value (Q>0.5) and a resonant center frequency "f", is there any equation that will tell you the phase/time delay induced ...
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1k views

### Why are so many wires coming out from a 3-phase transformer?

I want to make an arc welder from this stripped transformer. As far as I know it is a 3 phase transformer that could transform 380V to 12,24,40. I know how a regular 2 coil transformer works, but I ...
118 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 ...
1 vote
586 views

### Phase Difference Between Two Signals (Problem)

I am asked to calculate the phase difference between the two signals below. $$i_1 = -4\sin(377t + 55^\circ) \hspace{0.2cm}\quad \mathrm{and}\quad \hspace{0.2cm} i_2 = 5\cos(377t - 65^\circ)$$ What I ...
2k views

### Linear and non linear phase FIR filter

I am a confused about linear and non linear fir filter. I have this depiction of the solution space for linear-phase and nonlinear-phase FIR filters for a given set of specifications. Region 1 ...
1 vote
75 views

### Circuit for detecting signal inversion

I am using two inductors on both sides of an ac carrying straight wire and want to detect their proximity from the wire. The coils are a set distance apart and move together laterally via mechanical ...
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### How do I know the polarity of the resultant voltage of these two series-connected alternating voltage sources?

I was studying simple vector addition on All About Circuits, and the polarity assigned to the resultant voltage (see picture below) confused me. Link: https://www.allaboutcircuits.com/textbook/...
676 views

### How to find the phase spectrum of a rectangular pulse? (Fourier Transform)

How to find the phase spectrum of a rectangular pulse? The Fourier transform of a rectangular pulse  x(t) = \begin{cases} 1, & \text{for $|t| \le \tau /2$ } \\ 0, & \text{otherwise} \end{...
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### 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)(...
2k 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 ...
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I've got a signal that consists of 2 square waves at 2 different frequencies in the kHz range, about 10 Hz apart. I need to determine the relative amplitudes of 2 different known frequencies and I was ...
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1 vote
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### Transfer function of a digital phase frequency detector

I'm confused about the transfer function of a digital phase frequency detector. Why can we say that the pfd output is proportional to the phase error? The pfd (with charge pump) generates current ...
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### Measure phase difference with less than a full wave?

I am interested in aircraft altitude measurement during approach. Off the shelf sonar doesn't provide enough distance, and inexpensive radio sensors don't provide a short enough distance. I have seen ...
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### Low Noise Amplifier and Input/Output Phase

I've been designing LNAs for a brief time and I was wondering why the input and output phases is usually never cared for or measured when measuring the specs of the LNA. For example, the only specs we ...
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### How to specify the correct phase shift of special transfer functions ?

I know how to construct the Bode diagrams of first order and seconde order(Complexe conjugate) transfer functions. But here in the two examples below i confront some difficulties. I hope someone can ...
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### Phase-frequency detector not used in a PLL

My application: I need to output a voltage based on a phase difference between two input signals (a voltage and a current). It seems that a phase-frequency detector will do exactly this but I have ...
1 vote
790 views

### What is the purpose of these elements in this circuit?

I am analyzing this continuous waveform amplifier circuit for a Microwave Motion Sensor. This high gain amplifier is recommended in the datasheet as the signal output of the sensor is extremely small (...
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### Phase-modulated Noise

If you replace the carrier signal in a phase modulated circuit with noise then presumably the noise will be modulated. What must be considered if we wish to detect this noise modulation? I’ve ...
1 vote
767 views

### Can I rewire a 240 V 3 phase steamer to a 240 V 1-2 phase?

I have this steamer unit that came in as 240 V, 3 phase that I am trying to adapt to a 1 (2) phase household. The unit needs 60 A and generate 9 kW. As per the manufacturer, and the below diagrams, I ...
4k views

### How do i measure watts on single phase power?

With a clamp on amp meter, I have 8.2 amps at 123.6 volts on one leg and 7.2 amps at 123.9 volts on the 2nd leg. When I touch the volt meter to both legs I get 247.8 volts. What is the total wattage? ...
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### 240 V split phase and 240 V 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 ...
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### CE amplifier circuit gives output voltage that is not completely out of phase

This is the circuit that I have constructed But it fails to give the output voltage that is completely inverted (out of phase) Can anyone show me whats wrong with the circuit?
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### Different phases on different components

Say I have a typical wiring in my room where in I have two computers (A and B). A is a ...
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### How do power grids keep AC frequency synchronised across long distances with multiple generators? [duplicate]

Let's consider a simplified electricity grid - say there are two power plants (A and B) 1000km apart. There's a town (L1) half way between them, and another town (L2) some distance downstream from B. ...
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### Understanding phase noise specification in signal analyzer

I'm reading this datasheet and I see that phase noise is specified (page 12) in dBc/Hz for several offsets. I understand that that "Hz" in the unit means that the value is specified normalized to a 1 ...
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### 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.
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