Questions tagged [ac]
AC stands for Alternating Current. It usually applies to voltages with >100 V RMS, but can also be used for other AC voltages, like 24 V industrial AC power.
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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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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 ...
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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 ...
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Making measurements with oscilloscope on vehicle when earth and ground are common
I'm trying to make a small system that reads my engine data on my old bus.
I've used an LM1815 and to be sure, I've checked the input signal and output of the lm1815.
I've placed my probes and ground ...
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Switch neutral on 115VAC, 220VAC 1 and 3 phase mains power
I have an application that will switch primarily motor loads. It needs to cover US style 115V and both single and three phase 220 and 440 (really up to 460) Not all cases have a neutral.
I'm in a ...
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Trying to perform transient frequency response with LTspice or Microcap, TL494 compensation
I have tried to do Bode plot of my uncompensated plant by myself in LTspice 17.1, but the result looks strange to me. This topic is a follow-on to this one.. I have no clue why it comes with 290 ...
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How to detect the shorting/elimination of a 250 mA load in a 20 Vac circuit?
EDIT: My apologies -- I overlooked mentioning a critical fact: the "shorting" of the load is at times as fast as 50ms, and I need to detect that as well as events of the order of >1 ...
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How to properly calculate amps from home consumption metering system like Shelly EM?
I am creating a system for detailed measuring of power consumption in my home. For that I am using Shelly EM, which is using 50A hall sensor clamped over my main line (single phase 240V AC) inside my ...
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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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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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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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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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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-...
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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 ...
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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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Laplace transform 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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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 ...
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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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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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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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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 ...
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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, ...
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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, ...
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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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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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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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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 ...
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Right dimensioning of zero cross detection circuit
I need to detect the zero cross of AC main (220V - 50Hz) with an ESP32 to make a phase shift control of a resistive load.
Searching the web I found this circuit but I have some doubts on how to ...
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Transformer that doesn't take power when not used
With Is this (working) 2-doorbell system dangerous? and Why is it impossible to connect these two doorbells in series or parallel?, I arrived to the conclusion I need a new 220 V AC => 10 V AC ...
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Do I need a snubber in a snubberless triac?
I am trying to make this circuit and using the Triac as a switch. I am using in this one a BTA06, although I will upgrade it to a BTA12 so it can handle 220 V 1000 W easily. It will be implemented in ...
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What is the best setup for low frequency AC simulation and recording?
I need to apply an AC signal (current) of frequency, 0.1 Hz to a device and record the resulting change in voltage over time. I've been thinking a for a long time the best way to achieve this. I have ...
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Measuring power in AC
I have a heater running at 240VAC. I'm trying to measure the power by datalogging the voltage and current then multiply both inorder to get the power reading.
I know that this method works well with ...
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What is the simplest / most elegant way to passively select power supply based on voltage levels?
I have a problem and my thinking seems to be a bit stuck.
I want to design a power supply that works on both mains voltage (120VAC to 240VAC) and voltages below 24V (AC or DC). There's only a single 2 ...
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How does this protective circuit work?
Below is a circuit which I found that is used for protective earth neutral detection.
The PEN_ON comes from MCU and PEN_dET goes to an MCU.
P20 is a current transformer.
Can someone explain how this ...
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SANYOU relay wiring for HVAC
I'm having trouble with a Sanyou SLI-S—112DM relay. I'm using it Normally Open, connected to a 120 V AC compressor.
However, when I applied 12 V AC to the relay coil terminals, the compressor turned ...
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Comparing power requirements using AC and DC to power radio equipment
I'm trying to understand the different power requirements for a particular piece of radio equipment that I have. It has the capability of being powered via a bespoke AC or DC power supply.
The AC ...
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Unable to measure frequency response of a Wien bridge oscillator with Bode plot
I'm unable to get the Bode plot to work with this Wien bridge oscillator circuit.
Is there something wrong with my configuration, or does the Bode plot not work without an external signal source?
I ...
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AC Current Sensing LED indicator circuit
I'm playing around with a circuit to drive a LED based on the output from a current sensing transformer. The idea is to have the LED appear proportionally brighter with the output from the current ...
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Difference in amperage at the plug vs at the source (three-phase wye, 120 V and 208 V loads)
I'm trying to understand the difference between how my work calculates power at the load vs how we calculate the sum at the source.
We run temporary power and plug in several hundred industrial ...
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Winding coils in an AC generator
Assume a coil arrangement in an AC generator like the one seen below:
Given that the magnet has one pole on each side (2 poles in total in the magnet), how must the surrounding coils be wound? In ...
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Induction vs BLDC generators
I am doing research on wind generation to power local equipment. A sub-project involves choosing the generator and defining the control method.
I am interested in understanding why one motor type is ...
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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 ...
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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 ...
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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 ...
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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 ...
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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,...
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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 ...
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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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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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