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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3answers
68 views

How can current be in different phases in the same wire at the same time?

We know that either in ideal or practical transformer in no-load condition, the exciting current has two components Ic(core loss component) and Im(magnetizing component). Now since the same current ...
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44 views

AC MOSFET amplifier design problem

The source follower amplifier circuit shown in following figure transistor parameters are Vth = 1.2 V, kn = 4 mA/V2, λ = 0.01 V-1. Assume that gm = 11.5 mA/V. Vdd = 12. Design the values of R1, R2, ...
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40 views

New to AC to DC conversion!

I'm new to this forum, so apologies if I am posting this in the wrong place. I am looking to start a DIY project, and this entails electricity and water; I know, two things that shouldn't ever be ...
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Is it safe to touch 200 volts DC?

I was watching this YouTube video. The content maker simply declared that 200/300 volts DC is safe to touch. I think the capacitor used in that circuit is limiting the current. That's why nothing ...
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Microcap BJT amplifier DC and AC analysis

I am using to simulate DC and AC amplifiers of 2n3904 but it does not match with my theoretical calculations. My simple circuit is in attachment. Normally IB must be 28,12 uA but it seems 14.9 uA. ...
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74 views

Why is the output DC voltage of full wave rectifier not equal to the RMS of the original AC input?

https://www.electronics-tutorials.ws/accircuits/average-voltage.html https://www.electronics-tutorials.ws/accircuits/rms-voltage.html I understand that the RMS of an AC voltage is the magnitude of ...
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1answer
59 views

How to use a sprinkler valve in multiple zones?

I am currently setting up an outside irrigation system. When I built the system, I thought the irrigation controller would allow me to power multiple zones at the same time, and that each valve - ...
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3answers
49 views

Zero cross detector output

I have realized what I thought was a classic zero cross detector circuit using an H11AA1 chip: https://www.digikey.com/product-detail/en/on-semiconductor/H11AA1SR2M/H11AA1SR2MCT-ND/2094174 My circuit ...
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3answers
86 views

How to run a DC device through 3 phace 400V AC mains?

So I need to put a wifi antenna on farmland, the issue is that the antenna needs 12V DC powered over Ethernet and the only power source nearby is a 3phase 400V AC one... So is there something like a ...
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19 views

Why can the total connected load be equal to system capacity ? what does “maximum demand of the entire system” really mean?

I read some factor in the power transmission ,and there are something i don't really understand Question 1 demand factor \$ = \frac{maximum \ demand}{total \ connected \ load }=\frac{maximum \ ...
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1answer
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splicing ac adaptor cord which is positive and which is negative?

i lost my original asus router power adaptor. so i have a 12v power adaptor with a tip that fits my 19v asus wifi router, and i have a old 19v power adaptor that has a tip that is too small to fit my ...
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re model of transistor

In which case shall I consider output resistance(ro)? I found that in case of re model for common emitter configuration we are considering output resistance(ro) but there is no (ro) in emitter ...
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2answers
60 views

An AC generator can 'lock up' if its timing is off? [closed]

I believe I read elsewhere on Stack Exchange (Physics or Electrical Engineering) about how an alternating current generator can seize up if the frequency of the current does not match something else ...
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2answers
55 views

ltspice simulations is so slow

i have to make transient simulation of .wav file signal for my project. I tried to change general options for calculating but no results. I think my circuit is complicated for ltspice and simulation ...
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3answers
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How much 12V DC current can I safely draw from an AC 230V 13A socket and why?

In my cabin I have a sollar cell and a 12V battery that I use to power my electronics. However I'm dissatisfied with the standard CL sockets used in cars (apparently I'm not the only one) and I ...
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1answer
60 views

Very simple AC voltage question

How to simplify these two voltage sources (same frequency) into one so I can calculate the current then the power absorbed by each element
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1answer
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Wiring an air conditioner blower motor in a Ford Mustang

I am having some wiring issues with my vehicle following a fender bender. Everything on my air conditioner works as expected except for the blower motor. I can confirm it is a new blower with issues ...
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LTspice - Extracting magnitude of signal from AC analysis using .meas and the phase

I want to be able to produce a measure function such that the output of that function would give me the magnitude of a signal when its phase is -360deg. I tried using .meas AC name FIND mag(V(out)) ...
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1answer
29 views

Some doubs regarding AC/negative voltages in an audio signal

I know that audio signals are AC signals (negative/positive voltage). Assume a typical Fuzz (guitar pedal) effect circuit below. It seems signals stay between 0 and 9 V (9V is the power/battery ...
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1answer
55 views

Identify the component

In the given question, I see figure 3 has a common terminal which is more likely to be a full wave rectifier and figure 4 has 4 terminals which resemble that of a bridge rectifier, am I correct in ...
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2answers
74 views

Controlling a 3 speed AC ceiling fan motor with a Raspberry Pi

I have been trying to reverse engineer a ceiling fan remote control receiver to work with a Raspberry Pi Zero W. The light portion of the fan was easy enough to control, but I can't figure out how to ...
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77 views

How can a transformer convert the voltage of the same wire before and after connection?

Today I discovered a very strange thing, this transformer in the picture below, has 3 phases as input, and the output varies as you can see in the picture, the weird thing is that when I measure the ...
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2answers
40 views

why is \$|V_C|=90\$, not \$70\$? series RLC circuit

If \$|V_S|=100V\$,\$|V_R|=60V\$,and \$|V_L|=10V\$,then what is \$|V_C|\$ ? simulate this circuit – Schematic created using CircuitLab My solution \$100=\sqrt{60^2+(10-V_C)^2}\$,so \$(10-V_C)^...
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41 views

why is \$P^{max}_{Z_L}=|\hat I_L|^2\times 4\$,not \$|\hat I_L|^2\times 5\$,when \$\hat Z_L=\hat Z^*_{th}=4-3jΩ\$

What is the max power of \$\hat Z_L ,P^{max}_{Z_L},\$ when the \$\hat Z_{th}=4+3j Ω\$?? First i know the Imaginary part of impedance will cause Reactive Power,so the real power can't be the same as ...
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4answers
7k views

Why can an AC circuit breaker not be used in DC circuits?

Let's assume that I want to use a 20-amp GE AC circuit breaker in a DC circuit. So, after testing it in a DC circuit with some loads and ammeter + clamp DC amp meter I find the current at which the ...
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1answer
76 views

Current and Voltage in an Inductor with an AC source! [duplicate]

This is the simulation of a RL circuit with an AC source. That AC source is connected with the circuit at the moment when the source voltage has zero phase angle with 5 volts peak. It can be seen ...
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2answers
58 views

Compensation of custom high voltage power supply

To test an offline switching PSU I decided to build a custom isolated high voltage variable PSU. The idea was to build a nice, small, low power equivalent of a variac and isolation transformer that is ...
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1answer
71 views

Explanation request of a circuit involving contactors, transformer and a 3-phase motor

I found this circuit in a machine, I removed it and installed a VFD instead. This is how it works: when current arrives, the motor starts rotating, and the contactors K2 K3 and K4 close one after ...
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2answers
110 views

Finding the wattage given on the bulb

Sorry for what might seem like a really simple question. I came across a LED bulb that has the following specs: It is rated for: 120VAC (which I assume is just because the wall voltage in the US is ...
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1answer
195 views

What gets wrong when I average AC voltage and current to get power?

Power is half the product of peak AC voltage and current (or product of its RMS voltage and current). But why is it wrong when I average first the voltage and current before getting the power? I get ...
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0answers
55 views

How can I modify a home standing fan to run at low RPM?

I have a house standing fan 220V AC. I need to do modification to make it run on 15 RPM (revolutions per minute), usually fan runs higher RPM than that. Is there a way to make my fan run around 15 ...
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2answers
61 views

AC behavior of a capacitor

While under DC current capacitors cause open circuit as time goes to infinity but under AC current they flow through capacitor. As I know Maxwell described this behavior as "Aether current". Is this ...
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2answers
62 views

Why the Inrush current increase with decreasing voltage?

Here are the voltage and current shown for the primary winding of a transformer or an ideal inductor when the voltage is sinusodial. My question is why the current is increasing when the voltage is ...
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2answers
56 views

Why are inductive loads an issue for the power grid?

I understand from Power = V_rms * I_rms * cos(phi) Being phi the phase difference between current and voltage. The power consumed by the a circuit is reduced in the case of having inductive or ...
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2answers
104 views

Current waveform in an inductor with AC source

If we connect an AC source with a pure inductor when AC source is going through 0 volts we get the following graph of the voltage and current. There are few things in the graph about which i am ...
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4answers
1k views

Free-as-in-beer power from neutral and ground?

I live in a house where each socket has 3 connections,: hot (phase) neutral ground Where: The voltage between hot and neutral is about 220V AC. The voltage between ground and neutral is about 2-3V ...
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1answer
33 views

What is this add-on to my 1980s AC magnetic contactor?

I'm renovating a Shizuoka ST-N CNC knee mill with a Bandit 3 controller from ~1980 in it. The spindle drive is a Todai Electric Co DC Motor Control Pack model number MOP-1500 which has absolutely no ...
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1answer
45 views

AC-AC Converter 3 phase, Line to line voltage calculation

I’m working one some assignment like this circuit (AC-AC converter 3 phase, 89 degree firing period). I've done this on PSIM software with 110 Volts 3 phase voltage source. I've been told to analyze ...
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3answers
87 views

Got 2 gang light switch, common load, design circuit to know ON/OFF state of switches on each wire

Goal is to be able to use standard wall 2 gang light switch to: a) provide line connection with either of two / both hot wires coming from the same 230VAC phase to the ceiling for AC-DC 48V PSU ...
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1answer
52 views

Inrush and steady state current in an Inductor with AC voltage

I have two statements here from two great men. One says "If you apply AC voltage to the solenoid at the peak of the waveform then there is little or no inrush current whereas if the solenoid is ...
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3answers
40 views

Sourcing a Relay for AC Power Loss on UPS

I have a system outdoors (~200W) that is powered from the house with a battery backup on UPS. When the UPS switches over to battery power, there is no way to currently generate a notification that the ...
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2answers
50 views

How to calculate the safe AC frequency at high Voltages?

If someone wanted to build some kind of machine which produces HUGE and completely safe electric arcs, how would you calculate the frequency of the AC current in relation to Volt to make it safe? Why ...
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1answer
93 views

Is there a way to recycle/use negative half of AC voltage from a rectifier?

Forgive me, as I am far from an electrical engineer, but when rectifiers were explained to me I found that a rectifier allows current only in one direction, which allows it to filter out negative ...
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9answers
2k views

Why harmonic distortion and not at other frequencies?

Despite searching I can't seem to find the answer to this. In understanding harmonic distortion, one piece of the puzzle that is missing for me is: - why does the distortion manifest at harmonic ...
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0answers
25 views

Using a triac plus an H-bridge to switch DC or AC

I've been working on a controller for inductive loads, and I want the system to be compatible with either DC or AC loads. I've got a 24V to 34V DC boost regulator powering an H-bridge, which is ...
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2answers
59 views

Why do I get these voltage offsets when modeling an RC circuit with an AC voltage source?

During one of my homeworks recently, I became interested in modeling an editable graph of an RC circuit charge and current with respect to time. I used the formula that was derived step by step in my ...
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32 views

Inductor with ac and dc

When a dc voltage source is connected with a pure inductor And the switch is closed We get a change in voltage across inductor and along with it a also an attempt to change the current across the ...
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1answer
30 views

Transient response of a step RL circuit

In the following problem, the equation i(t) = i(∞) + [i(0+) − i(∞)]e^(−t/τ) was used to calculate the current at time t given the initial and final currents. Then, vo(t) was found by equating it to L(...
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0answers
64 views

Protect DC circuit from AC

First and foremost, I would like to point out that I am a beginner in electronics. I have designed a board that is meant to be connected to 240V AC. However, there is a relay on it that has a 12V DC ...
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0answers
29 views

Creepage between Phase/Neutral and Earth (PCB Design)

The smallest distance between line and neutral on my PCB is 4mm, which ought to be enough for 240V mains. I had a copper pour connected to earth around every trace with a clearance of 1mm. Someone ...

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