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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50 views

Alternative way to power a mains 12 watt LED

So I'm pretty excited, I'm about to finish my project but now my problem is I bought a bulb led today and I do not have anymore resources to provide a 60hz 230v to it, since that is its specification. ...
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22 views

Overvoltage protection when going from 24V AC to 3.3V DC

I'm trying to wrap my head around transient voltage protection and how to implement it when also trying to rectify a AC source to DC then step it down to 3.3V for a microcontroller. I understand that ...
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1answer
50 views

Drop voltage of a doorbell transformer

I am trying to install a video doorbell that requires an 18-24VAC supply voltage. The existing doorbell is supplying 28V. How can I use a resistor to drop the voltage down to something below 24VAC so ...
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39 views

Why voltage in capacitor lags behind the source voltage in RC circuit?

Voltage across the capacitor lags behind the current through capacitor as we know. But why the voltage across the capacitor lags behind the source voltage in this circuit ? Similarly it is found that ...
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57 views

Inductor time variable current

At t0<0 the current through the inductor was 0. simulate this circuit – Schematic created using CircuitLab At time t0 we introduce a current source and a resistor to the solenoid The current ...
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135 views

How to amplify sine wave with op-amp

I am trying to build my own function generator. I put together a Wien bridge oscillator but I get very low output voltage. I wanted to connect it to an op-amp to simply increase it. I connected the ...
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1answer
84 views

What is the Thevenin equivalent of this low-pass filter?

I am trying to calculate the Thevenin equivalent circuit of this low pass filter however, I have never done it with an AC input and am getting very confused. $$R = 100\Omega ; C = 2\mu F$$ $$Vin = ...
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43 views

AC parallel and series circuit

I have this AC circuit: simulate this circuit – Schematic created using CircuitLab I have found VA which is \$222 \angle-119 mV\$. The current flowing through the inductor \$IL = 2.6 \angle-89 ...
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37 views

Filtering AC Control Signals

I'm having a problem with odd noises in my guitar amp and I'm really struggling to find anything online. Here's a sample of the noise: https://www.dropbox.com/s/z7ggll3q6219l0o/Noise.mp3?dl=0 I've ...
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1answer
56 views

Why reactive components have less influence at low frequencies?

Some textbooks state that reactive components (may) have less influence at low frequencies, since inductance and capacitance are generally more significant at hifh freqs. "Pratical electronics ...
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1answer
79 views

AC circuit voltages and currents

I have this circuit: Have I done everything correctly? I cannot find my mistake. Help appreciated.
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2answers
55 views

AC circuit capacitor voltage drop

Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab Z = 4-3j I = V/Z = 1<0/5<36 = 0.2< -36 A But when I use Ohm's law on the capacitor i get this ...
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77 views

Does this voltage logic make sense? [closed]

In India, stabilizers have to be used for ACs. At least that's what people say because voltage fluctuation is common here. I'm buying this Air Conditioner and was thinking about to buy this Voltage ...
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3answers
97 views

Where do you put the inverter? Near the battery or near the load?

Where do you put the inverter to minimize power loss on a stand alone solar setup? I'm using DC 12V as power on devices but I notice resistance on wires when running long lengths. AC is better on long ...
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Could i use an AC Arc welder as a Dimmer [closed]

i am trying to slow down my electric jigsaw a little bit. Since it needs a lower voltage in order to achieve that i came up with the idea of using an old and heavy arc welder, which only consists of a ...
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1answer
47 views

How to connect single-phase power source to 3-phase motor

My 3-phase, wye wound, 9-lead motor has: wires 1 & 7 connected to wire L1 2 & 8 connected to L2 3 & 9 connected to L3 and 4, 5, 6 wired together. I put a plug on one end of a cable, that ...
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3answers
74 views

does hot and neutral wire produce less heat in a single conduit than in two separate conduits?

an electrician is telling me that having the 2 conductors (hot and neutral) for a branch circuit from my home Electrical Panel in the same buried conduit will produce less heat because the 2 magnetic ...
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3answers
324 views

What is the impedance for this parallel rl circuit?

I want your feedback on my approach to solving the question. I also want clarification on the phase angle for the inductive reactance.
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4answers
827 views

Definition of RLC resonance frequency

I have found that a commonly mentioned definition for the resonance frequency in an RLC circuit is defined as the condition where the capacitive and inductive reactances cancel each other, resulting ...
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1answer
61 views

Input and Output Voltage of a Full bridge rectifier

I know If we provide a sinusoidal AC Voltage across the Inputs of a full bridge rectifier we get a fluctuating DC Voltage (more or less) with the peaks of source AC Voltage. But what would be the peak ...
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31 views

How to stabilize and add additional power to an existent line?

My first question on this Exchange so I hope this is the right place for it. Currently, I have a quite unstable power supply in my workshop, coming from a very old electrical installation. It is a ...
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1answer
49 views

Easiest way to (quietly) drive a 2W 120VAC load (piezo air pump) from MCU-controlled 3V/5V/12V?

I'm trying to drive this piezoelectric air pump that requires 1.5W and runs on 120VAC 60Hz wall power. This will be controlled by a MCU/CPU of some kind (Raspberry Pi in this instance), so the control ...
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1answer
40 views

Phototriac for low voltage AC motor control without external triac

I have a circuit that does not work as expected. It uses a MOC3023 phototriac to directly control a 12V AC pump. Since the motor is very low power I assumed I wouldn't need an external triac. This may ...
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3answers
65 views

Voltage and current during the first cycle of RL circuit

I have a simulation of RL circuit connected with an ac source. Any one can tell me please that why the peak of the current during the first positive half cycle is higher than the peak of current ...
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1answer
91 views

Danger of inserting knitting needles into an electrical outlet

When I was a little kid (read: inexperienced), a friend of mine claimed (as his mother warned him) that putting metallic things into an electrical outlet is dangerous. Kids are curious. In order to ...
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1answer
47 views

Power adapter 13.5V vs 15V

I'm trying to troubleshoot a problem with my Creative Inspire T6100 speakers. They seem to be known for volume control issues. In any case, I'm trying to determine if the power adapter is working as ...
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1answer
48 views

UV-C lamps flickering problem

I have got 8 UV-C lamps connected to a portable battery(AC) through a smartplug. I am using 4 UV Ballast with 2 lamps connected to one ballast. I am controlling the lamps with help of a wireless ...
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4answers
98 views

Transients in series RL circuit with AC source

Why the transient current will die off in series RL circuit with AC source ? Every time the ac voltage source reverses direction so does the current and the current has to pass through the same ...
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1answer
27 views

Using a dual winding transformer to provide dual winding AC and DC of a single winding

Ok, this feels like a stupid question, but my google-fu is not with me today. I have an application in which I have a need for both 12V DC (or thereabout) and 24V AC. I have a transformer that has two ...
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0answers
34 views

Safest / preferred ordering of AC terminal block terminals?

I'm building an enclosure for a switching device that has 5 outputs: Ground (G), two AC neutrals (N), 120 VAC hot (H), switched 120 VAC hot (HS), up to 12 amps per H/N pair but no more than 15 amps ...
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1answer
38 views

Voltage gain, input/output impedance using multisim.. How? [closed]

This is the picture of my amplifier circuit using multisim... But I'm not very familiar with this software and thus... how do I do the AC analysis to get the voltage gain, input/output impedance...?
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1answer
90 views

Wiring 240 V single-phase AC induction motor to enable operation forward and reverse on a 2-post ramp pulley system

I installed a single phase motor on a car ramp. I need the motor to operate forward and reverse, so the ramp goes up or down. I understand this is possible with the use of two contactors. I need the ...
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1answer
84 views

How can I reduce 120 VAC 60 Hz gradually to zero in a 8 seconds?

Need help on a project where after a pressing a button 120 VAC voltage drops gradually to 0V in 8 seconds. Second button will restore full voltage again. Load is a big magnet and its current can be as ...
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5answers
481 views

Reactive power in AC circuit

What is meant by reactive power in AC circuits? Power is joules per second. Real power is the energy dissipated in the resistor per second. What is meant by the reactive power? Does this mean the ...
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2answers
50 views

Phase shift in AC Circuit power calculation

I have the below question. I am not trying to ask the answer for the problem. But my question is that, we can see that 60deg is the phase shift. But both the voltage and current across the passive ...
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2answers
49 views

Connect motor in 220 VAC single phase (Line - Neutral) or in 110VAC two phases (110VAC - 110VAC “180 degree out of phase”)?

I need to connect A motor of 220VAC to single phase connection :Line - Neutral(220VAC - Neutral). In my country that doesn't exist so in my country we have this : L1-L2-neutral (110VAC - 110VAC "...
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1answer
92 views

Converting from time domain to phasor domain?

If I have a voltage source of a circuit \$V_s(t) = 8\cos(24\pi*10^9t-60^{\circ})\$ (V) and I want to convert it to the phasor domain would it be this? \$8e^{-j60^{\circ}}\$?
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3answers
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Transformer power supplies, which one would have a 24VAC secondary when the DC output is 9vdc > 12vdc > 15vdc > 32vdc

I need 24VAC 300ma for a solenoid and have these old transformer power packs with outputs of: 9vdc, 12vdc, 15vdc, 32vdc. I'm willing to crack open one and use the transformer but I only want to open ...
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2answers
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Theory: Can power cables induce AC voltage in human body?

In a demo video (which I unfortunately can't share) a man makes the following setup: Multimeter on 200 V AC settings with one pin in the ground socket of a conventional mains power socket. Right ...
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1k views

How to remove huge spikes in current

I am making an DC to AC converter circuit in LTSpice. The schematic is posted below. When I plot the current across the transistors, I get huge spikes in the current, as seen in the diagrams below. ...
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1answer
66 views

How to design a square wave inverter circuit without an op amp

I am using an NE555 timer circuit to generate a 0 to 12 volt 10kHz square wave. I would like to invert that square wave (so inverted signal is 0 when original is 12V and 12V when the original is 0 V.) ...
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4answers
124 views

How can capacitors pass AC without or with minimal voltage passing?

My question is: How can capacitors pass AC without or with minimal voltage passing? If the current is caused by a voltage (potential) difference and current is just the voltage (or charge) passing per ...
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1answer
44 views

Harmonics produced by LCC converters

Considering an LCC HVDC system and that the flow of power is ALWAYS in the direction shown in the figure. I know that converters in general produce harmonics. My questions are: Does this HVDC system ...
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3answers
50 views

Single capacitor for Powerline communication - AC coupling

First of all: I am not talking about traditional powerline communication (ethernet protocol etc) but about a very simple and primitive communication, like serial data transmission (https://en....
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3answers
51 views

Do switches induce voltage spikes in the AC power grid?

I know that DC inductive loads create back EMF when turned off and that's why we use a freewheeling diode. Does this also true for AC inductive loads and AC loads in general? I know we can't use a ...
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4answers
456 views

How are the -3dB point and the pole of an op-amp related?

I have been looking at AC frequency responses for op-amps and I was wondering how an op-amp's pole and the frequency at the -3dB point are the same? They both mark the location where the gain starts ...
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2answers
55 views

Is this LDR and TRIAC circuit advisable for real time application?

Would you suggest below circuit? Will it work for a long time? What are the advantage and disadvantages of this circuit? https://envirementalb.com/automatic-street-light-circuit/
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1answer
101 views

Why do some motors have both 50Hz and 60Hz on their nameplate, and some do not?

I have seen some induction motors have information on their nameplate listed for 50hz and 60hz. While I've read a requirement that the Voltage/Frequency ratio be consistent, using these nameplate ...
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7answers
1k views

Why do single transistor oscillators work to power a transformer, if a transformer needs AC?

I have been making some high voltage projects lately, such as a spark gap Tesla coil, slayer exciter, and a flyback transformer HV supply. The flyback transformer uses a single transistor circuit, ...
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9answers
5k views

Is this an AC or DC signal?

My teacher says that this signal is DC, but if the polarity varies from 0V to -8V , shouldn't it be AC? He says that DC + AC = DC

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