Questions tagged [ac]

This tag refers to alternating current mains power. It usually applies to voltages with >100V RMS, but can also be used for ex. 24V industrial AC power.

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What's wrong with my input circuit? LTspice

I am designing my first power electronics board in LTspice to convert single phase AC to DC. This DC is fed to asymmetric bridge to drive an SR motor which is connected to a flywheel. This flywheel ...
2 votes
1 answer
52 views

Why are there two different charges on a patch antenna? How are these charge distributions formed?

If we apply an AC signal to a capacitor, we can see only one type of charge on an individual plate. If we apply an AC signal to a patch antenna, there are two different charge distributions on the ...
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Hark There is an Arc

AC mains power is almost always transmitted at 50 or 60 Hz. Accepted reasoning is that lower frequencies make transformers larger and higher frequencies have greater transmission losses. ...
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2 votes
2 answers
84 views

Does acceleration come from a change in current?

I have a current connected to a wire and let's say when we measure the current at a particular time it reads differently than it does after some time. Does this imply the current is AC? I'm asking ...
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2 votes
1 answer
89 views

Finding the mathematical function that describes voltage across diode and resistor circuit

I have the following circuit: simulate this circuit – Schematic created using CircuitLab Where \$\text{V}_\text{i}\left(t\right)=\hat{\text{u}}\sin\left(\omega t+\varphi\right)\$ and the ...
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When talking of mains leakage current, presumably this is an AC phenomenon. Can it cancel and/or is it filterable?

I have recently learned that switching power supplies tend to push up to the limit of 3.5 mA leakage to the ground wire on the mains supply. Presumably this is entirely AC, 3.5 mA RMS, and there is no ...
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2 votes
1 answer
363 views

Optocoupler 4N25 cut and saturation for zero crossing detector circuit

This is my first time working with an optocoupler and I'm trying to find the right resistors for a zero crossing detector circuit that has a 4N25 optocoupler, but the values I've calculated are not ...
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2 votes
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104 views

Multimeter and clamp give different AC current measurement

I am trying to measure the power output of an AC permanent magnet motor to a load (a resistor). To do this, I am measuring the current through the resistor, and the voltage across the resistor. To ...
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2 votes
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346 views

Frequency-dependent behavior of R and L in LTspice

I have this question that I have been dealing with for quite some time now. Say I have an electrical machine that I model using lumped parameter (RLC circuit). As we all know, R and L are frequency-...
2 votes
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33 views

wave form of the diode current of a rectifier circuit and difference between the transformer and the AC source

So I have two questions I hope you would answer it, the first one is about how would the current Id of this circuits be? I mean his waveform. and my second question is these two circuits who are in ...
2 votes
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70 views

Switching n-MOSFET as Solid-State Relay

I'm trying to design a simple solid state relay that can be in the off state when an AC Source is applied (schematic one) and then source up to 150mA to a small resistor when that AC Source is removed ...
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2 votes
1 answer
519 views

Laplace tranfsorm of capacitor functions and initial conditions

I may be asking something trivial, but unfortunately, I could not find an answer so far. Suppose an AC circuit. The voltage of the capacitor is given by $$v_C(t)=Q(t)/C = 1/C [ \int_0^t i_C(τ)dτ + v_C(...
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159 views

How to solve for V0 in the next circuit

How can I solve for V0 on the next circuit if Z1 = 1, Z2 = j, Z3 = -j. All the ways I'v tried, V0 depends ends depending on V0, maybe using superposition theorem? Attempt 1: ( Calculating current ...
2 votes
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517 views

Why should the primary winding of the transformer not be grounded?

I've been wondering what would happen if you grounded both star points of a Y/Y connected transformer. This shouldn't affect the voltages, so why really is it not advised to earth both the primary ...
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746 views

Admittance, Conductance, Susceptance definition

Admittance is the reciprocal of impedance. But: 1) Susceptance is the reciprocal of reactance, or the imaginary part of admittance ? 2) Conductance is the reciprocal of resistance, or the real part ...
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2 votes
1 answer
289 views

Power amplifier simulation and real time experiment mismatch problem

Thanks in advance to anyone who will take the time to read my first post here. At present, I am doing a simulation of a power amplifier in LTSPice. The schematic and relevant files are uploaded in a ...
2 votes
2 answers
546 views

How to determine the right trip point of thermal cutoff for 1/4 hp 3A 115V single phase ac motor

The Thermal fuse blew in my Ryobi DP102L drill press motor, while I was drum sanding. There were no markings on the fuse. The single phase induction motor is 1/4hp 3A (no load) 1750rpm on 115V AC, ...
2 votes
0 answers
270 views

Tricky AC power Question

Greetings all, Just to be clear, I am not asking anyone to do my homework. I am simply asking for guidance and or to clarify any conceptual errors I am making. For the following question, ...
2 votes
3 answers
743 views

HVAC fan relay intermittently sticks closed; opens when touched

I have constructed a simple OR gate using two HVAC fan relays to control a 120VAC/1.5A booster fan for my home HVAC system. I have a zoned system, with multiple thermostats, but only one zone/...
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2 votes
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1k views

Calculating signal attenuation for AC?

So we've got this; simulate this circuit – Schematic created using CircuitLab Which I've been told is equivalent to the sum of it's Coutputs to an AC signal; simulate this circuit So then; $...
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5k views

What's the theory behind speed control of a multi-tap multi-pole induction motor?

Ceiling fans are an application of multiple-pole capacitor-run/permanent split capacitor induction motors, and they appear to control the speed through a partially powering and shunting multiple-tap ...
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835 views

Why does a multimeter in resistance mode show initial continuity over a diode?

I originally phrased this question very differently; the original text is retained below in case background information is useful to clarify the context. When I using this digital multimeter to ...
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2 votes
0 answers
314 views

Control DC circuit with an AC lock switch

I am currently adding circuit with a horn and some lights powered by a motorcycle battery. The circuit should be using about 12v 18A. What I want to do is control the circuit with a lock switch. I've ...
2 votes
1 answer
126 views

Is there a pattern to where various industrial AC voltages are used?

AC voltages in the "low voltage" class vary quite a bit. I've seen nominal voltages of 208, 220-240, 277, 380-415, 460-480, 575-600, and 690 VAC. Past that I don't see anything until medium voltage ...
1 vote
0 answers
44 views

Multiple feeds from a single AC source

Rather than have a line of plugs in a 3-gang extension on top of my kitchen cabinets, I thought that if I split the feed, then fuse and switch each power supply for each LED strip, it would be an ...
1 vote
1 answer
86 views

Battery replacement for 16 VAC

I have a mains power adapter that powers a small model train set. I would like the option to power this off a rechargeable battery, although I'm not sure this is possible, as it uses AC. My current ...
1 vote
1 answer
51 views

Multiple AC-DC power supplies: one direct AC wall plug or two?

I'm building a data acquisition system that needs to power sensors and a high voltage contactor at 24Vdc, 12Vdc, and 5Vdc. After reading another post, it seems it is best to use separate AC-DC power ...
1 vote
0 answers
71 views

High-voltage resistors versus anti-surge resistors

I am making a voltage divider with four 1M 1206 thick-film resistors and a single 2.7k resistor. The input to this voltage divider will be mains line and neutral. I want to measure the voltage at line ...
1 vote
0 answers
67 views

Identify Vintage Power Cord for Sears Electric Tray

I found this vintage Sears electric warming tray but it's missing a power cord. I tried a 2 prong figure 8 cord but the holes were too close together or too small to fit. Here are pictures of the tray,...
1 vote
0 answers
67 views

Running 230VAC through a PCB

I've currently got a system which runs 230VAC, 24A through a series of 3 groups of 8 terminal blocks (8A each group, 1A per terminal block), through a relay each (8A), and then through 3 terminal ...
1 vote
1 answer
210 views

Portable AC power source earthing?

I have an 12V to 230V inverter in my car but get confused about ground it. The inverter is centre-tapped, means live-earth voltage is +115V, neutral-earth voltage is -115V, this gives an L-N voltage ...
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1 vote
1 answer
113 views

Diode in series with a resistor an in parallel with another resistor

I have been facing some troubles with this problem. My main concern is that if Vab = 0.7 (when V(t) > 0 V,) will the diode conduct? I think that isn't the case, but if that so I don´t know how to ...
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1 vote
1 answer
131 views

AC element control using TRIAC and optocoupler

I recently came across this circuit and I'm trying to understand it. This is designed to control an AC heater using a T435-600B-TR TRIAC and an MOC3063S optocoupler, connected to an Arduino Uno. From ...
1 vote
1 answer
75 views

Transmission Line Power Flow

Background: So, I recently watched Veritasium's video, "The Big Misconception About Electricity" and EEVblog's response to it. Here is the circuit in question: I think understand why the ...
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1 vote
0 answers
191 views

Op-amp with AC input

I've just started learning about op-amps and something confused me in one of my lectures (apologies for the low quality, it's a screenshot): The output voltage is going into a rotational electro-...
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1 vote
0 answers
94 views

Output phase voltage of wye-connected synchronous generator

The question: The answer: However, theta is the angle difference between the terminal phase voltage and the line current as shown in Figure 20 below So, I think the answer would be 512/12 - 47/-34....
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1 vote
1 answer
63 views

Is there any AC voltage sensor available like as Rogowski coil for current?

I am making a device to measure AC voltage. I want to measure voltage just by clamping the probes around the wire (like we do with Rogowski coil to measure current). However, I am only able to find ...
1 vote
0 answers
99 views

High frequency AC power supply

I'm looking for methods to deliver a alternating current of 5 A at variable frequencies 0-20 kHz to an electromagnets to generate an alternating magnetic field. I've been reading various post and ...
1 vote
0 answers
254 views

Operate and speed control a 230V 50Hz AC Ceiling Fan with Power MOSFET based Dimmer Circuit

I am trying to control the speed of ceiling fan at my home using a power MOSFET based dimmer circuit. The ceiling fan operates at 230V AC and can consume maximum 50 to 75 Watts power. The circuit ...
1 vote
0 answers
41 views

Winding Factor in Single Phase Induction Motors

How does one compute the winding factor in a Single Phase Induction Motor? I have checked Wikipedia, but it only states the relevant formulae for three-phase machines with no explanation of the theory....
1 vote
1 answer
233 views

DC AC Inverter topologies

I am trying to get a deeper understanding of sine wave inverters (like this one) and thereby came across different topologies like a Push pull inverter with a center taped transformer or a full bridge ...
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What determines the frequency of a ZVS driver

Schematic of ZVS driver Output waveform of transformer Determining frequency from time difference between peaks of output waveform at secondary coil of transformer I was simulating a ZVS driver in ...
1 vote
1 answer
293 views

What factors affect the voltage drop in a basic AC generator when an additional load is added in parallel

As a preface, I am in school to become an engineer on a ship so my question relates to a self-contained circuit/grid and not a home. We are going over generator theory and how an automatic voltage ...
1 vote
0 answers
104 views

How to solve this circuit (phase shift across resistor)?

I can't figure how do I proceed to solve this problem- Vin is given as 2cos100t, Vout is 2cos(100t-π/2) and R=1k. C is to be found. What I've done and where I'm stuck - I know that V- terminal will ...
1 vote
0 answers
71 views

Opinions for motorhome mains AC switching circuit design

We are located in Europe, and building a motorhome. Currently I plan the electrical wiring for the mains 230V AC. We will use a 24V / 230V 2kW inverter from battery, but when we have the possibility ...
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1 vote
1 answer
127 views

Possible capacitive coupling on soldering iron

I have bought a cheap soldering iron. It seems to work fine. Out of curiosity I tested the metal enclosure (and thus also the tip) with an electric tester and it lit up. Then I tested it with a multi-...
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1 vote
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67 views

Cheapest inverter to produce 24VAC

I'm working on a sprinkler/lighting controller project where I need to supply solenoids with 24VAC and lighting fixtures with 12VAC. I can use a different circuit for each. The input to the system is ...
1 vote
0 answers
90 views

Control a 110v AC motor with a 5v digitally controlled potentiometer

I have a manual variable resistor(turn the knob) connected between 110v and an ac motor that pumps air to make bubbles in my portable hot tub. I have had it for about a year and it works fine to ...
1 vote
0 answers
189 views

How do I properly ground DC and AC in the same enclosure (DIN rail)?

I am building an electrical panel with AC and DC supplied power. My AC ground wires connect to a green DIN rail connector which has metal on the bottom of this terminal and connects to the DIN rail ...
1 vote
0 answers
60 views

What is the material of AC outlet plug pins? Is it standardized? Are they usually just stainless steel?

^ The title. I want to know if the material is food safe and wanted to know if it would be toxic if introduced into a material that will be consumed. It will be exposed to liquid constantly and I don'...
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