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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2answers
26 views

Identify coils end in 3 phase AC induction motor for star-delta configuration

In general if I look at a 3 phase AC motor outlet wires there are six wires that comes out of motor, three of them are marked to show coils end and other three are not marked which show coils other ...
8
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8answers
2k views

Can you theoretically have AC with frequency less than 1 Hz?

We had a big argument last night with vague conclusions. Is the current with a frequency less than 1 Hz considered DC? It would still resemble a wave...
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0answers
63 views

Keep volts the same but increase the amps in a 60hz 120v AC circuit

I have a over the range microwave with a built in fan for exhausting range fumes below. Would like to add an inline fan to it in the attic that matches the speed of the fan in the microwave but I ...
0
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0answers
34 views

AC Motor operating region

I've been using an ABB IRB 2400 robotic arm to gain experimental data and write a report based on the data. I found that when I operated it at different speeds for pre-programmed paths, I got a ...
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0answers
126 views

AC Main measurement IC [migrated]

I need to detect low voltage AC power. Can you please suggest a method using micro controller to achieve this? I have made an attempt at this by converting it to DC, but there is a large fluctuation ...
2
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1answer
76 views

Why doesn't the RMS current and voltage give me average power?

Apologies for the multiple bridge rectifier questions. I have a 230V/9V 10VA transformer, and I want to know how much DC current I can draw from this circuit. From this I assume that the ...
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0answers
64 views

How can a circuit output have voltage, but no power?

I am building a triac/diac circuit for a motor. Currently, I am testing it with only 16V AC to see if it works. I don't want to risk electrocution. I am encountering a problem where the output voltage ...
1
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3answers
68 views

Why does the current waveform become non-linear in a bridge rectifier?

This is my bridge rectifier circuit, and I'm trying to understand why the current waveform of the source deforms the way it does when you approach an ideal capacitor. Source V1 is 9VAC. I simulated ...
0
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1answer
84 views

Capacitive transformerless power supply, AC polarity problem

I have implemented a "Capacitive transformerless power supply" to control a microcontroller-based circuit that contains capacitive touch sensors, and I had an "AC polarity problem" Surprisingly, the ...
2
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4answers
106 views

Whats the point in conserving electricity if the AC current produced cannot be stored?

If we cannot save the ac current produced in a battery or some device like the DC current there is no point in conserving it because current once produced should be consumed somehow!! My faculty said ...
-2
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0answers
35 views

Dimmer Tutorial Using Diac and Triac [closed]

I want to make a dimmer circuit here in our house as Christmas gift to my self. But I am still student with limited knowledge so please kindly guide me and help me to build this my self-assessment ...
1
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1answer
37 views

Capacitance value - AC RC Circuit - Impedance Method

Here is the circuit: simulate this circuit – Schematic created using CircuitLab \$ V_i = \frac{8}{\sqrt 2} \angle0° V\\ V_c = \frac{6}{\sqrt 2} \angle45° V\\ R = 1000\space\Omega \$ ...
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1answer
31 views

Forced Response Test Bank Question

I'm trying to calculate the forced response for a current in the above problem. I'm having trouble getting the right answer, and I was hoping someone could take a look and point me in the right ...
1
vote
1answer
113 views

What are the AC characteristics of a battery?

I'm planning on building a single cell AA NiMH battery charger and in the process I decided that I must also build a battery simulator to help me debug the charger. In my research, the best simulator ...
2
votes
2answers
214 views

Type of switch for AC power cord?

I have a power supply that has only screw terminals for its AC mains input. Currently I'm using a power cord from a computer that I cut the female end off of and attached fork terminals to (live, ...
0
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1answer
26 views

Sinusoids and Phasors AC circuit impedance

Hello. I've been doing problems, and transforming from time domain to phasor domain to find input impedances seems simple enough But I've come across a circuit with a dependent voltage source, as ...
1
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2answers
42 views

Value of omega from forced response V0

Based on figure. Maybe a simple question, but I'd like to know why that if forced response is zero, then $$\omega L = \frac{1}{\omega C}$$ where \$L\$ is the inductance and \$C\$ is the ...
0
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0answers
41 views

using 2 Arduino Interrupts simultaneously to detect AC phase

I've built an AC power bar that is digitally dimmable using a modified version of this circuit. The modification is that I am using 2 separate AC power lines that would be connected to different ...
0
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0answers
66 views

provide 3.7v source to android tablet

Android tablet mostly needed a 3.7V Lion battery to run on it. If I were to replace the battery with a power source, how can I provide such a 3.7V source from some existing products such as 220V/5V or ...
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1answer
38 views

Mesh Analysis on AC circuit

I'm doing a practice problem and I'm unsure how my approach did not receive the same result as the solution. Any help would be appreciated. Below is the Figure along with the solution as well as my ...
2
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1answer
79 views

Power factor correction in a simple phasor circuit

I've been having a bit of trouble with a relatively simple power factor correction problem involving a simple circuit in the frequency domain (\$f=50\,\text{Hz},\omega=2\pi f=100\pi\,\text{rad/s}\$). ...
2
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0answers
65 views

Discrepency with experimental vs. simulation of AC-DC circuit

I'm analysing a PIR Circuit's power supply, but I'm having a large (almost double) discrepancy between simulation/theoretical current values and experimental values (experimental is almost half ...
0
votes
1answer
52 views

Where do I connect earth wire?

I'm trying to use this delay timer to control an exhaust fan. I have a 3 pin connection (with earthing wire) powering this fan and it works fine. If I have to insert this delay timer module in ...
0
votes
2answers
76 views

AC vs DC and ELF - extremely low frequency

given : How do static fields differ from time-varying fields ? A static field does not vary over time. A direct current (DC) is an electric current flowing in one direction only. In any ...
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1answer
33 views

Monitoring power from 3-phase AC generator

Hello all. The above is a circuit schematic (sorry for poor hand drawing) for monitoring power from 3-phase AC generator. The main goal of the circuit is to see how the power output varies depending ...
2
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2answers
105 views

PWM an AC pump using MOSFET

I'm currently stuck on my project as I'm not sure what to do with PWMing my pump as I want to adjust the pressure. I will be using an Arduino for PWM. The pump is 60W @ 230V 50Hz mains and is a ...
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1answer
46 views

AC Analysis Mindset [closed]

I'm just trying to solidify my foundational knowledge of ac analysis. So when approached with a basic circuit, lets say a RLC circuit, should my first instinct be to convert each group of components ...
0
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1answer
40 views

Power management at thermal power station

I have weird question, but I hope somebody can give at least hint what should I read to understand the concept. Imagine situation: There is thermal power station and a city that takes power from ...
0
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1answer
92 views

Why are these Vias of Different Shapes

While looking at how other circuits bring AC mains into their circuits, I came across this design where there are 3 differently shaped vias (from top to bottom): Figure of ...
1
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1answer
89 views

Current flow in AC vs DC

If a live wire is taken from AC and connected to a bulb, while the other terminal of the bulb is connected to ground, the bulb glows; but if I take the positive terminal of a battery (DC source) ...
0
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2answers
170 views

How does this circuit give DC output?

I don't understand how this circuit works. I'm not sure if it's correct. It should give a DC output, but how would it do that?
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2answers
61 views

How to make a duplex 7 segment display

I have built the circuit below and have been using a 7 segment display which is meant to be designed to work with the circuit. However there is no clear diagrams showing which wire on the display ...
0
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3answers
63 views

Making my own kotatsu

I want to make my own kotatsu (a small table with an heating element underneath) and I'm considering using a "heat lamp" as the heat source (one of those aimed at reptiles, fits in a normal light bulb ...
1
vote
1answer
44 views

Will a tvs diode help my relay with inductive loads?

I am not an EE, so please be gentle! I will obviously get a certified EE to review my design before anyone else touches this so please assume that I know enough to at least be safe with 120VAC and am ...
0
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1answer
48 views

What is ground on a circuit that uses AC?

Below is a circuit diagram for a circuit that runs off AC voltage. Where do I connect all of the points that connect to ground? Do I just connect them all on the same rail of a piece of Vero board? ...
1
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1answer
66 views

Powering a Digital Alarm Clock with AC

I have built a digital alarm clock using an LM8560 chip. I tried powering the circuit with DC and the 7 segment display lights up, but none of the buttons worked and the numbers on the 7 segment ...
0
votes
1answer
58 views

Why can we drop the Omega term in Euler's expression of AC signal?

I know that for an AC signal like $$V=V_p\cos(\omega t+ \phi)$$ we can simplify it to $$Re(V_p e^{j(\omega t+\phi)})$$ But why can we further simplify it by dropping the Omega term $$Re(V_p ...
0
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2answers
109 views

Can I solder back together a single broken copper winding wire in an electric washing machine motor? [closed]

Can I solder back together a single broken copper winding wire in an electric washing machine motor? This is the motor: ...
2
votes
3answers
274 views

LED bulb still emits light when turned off

I have recently purchased an IKEA LED bulb with G9 fittings, to replace a halogen one. This one. The bulb is installed in a lamp with 3 other halogen G9s in a 3 + 1 configuration with a 3-state ...
0
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1answer
30 views

Si8519 AC Current Sensor usage

I'm trying to find a good and practical current sensor and I found this: Si8519 http://www.silabs.com/Support%20Documents/TechnicalDocs/Si85xx.pdf My idea is monitor AC Mains current, so this Si8519 ...
1
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2answers
83 views

Measuring Electron Beam Currents

When it comes to measuring electron beam currents with a Faraday Cup (or any that will pick up electrons and act as an anode), primarily AC and transient signals, my understanding is that one can (1) ...
0
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1answer
59 views

Why should I use DC coupling when I'm finding the frequency response of a circuit?

In my last electrical measurements lab I was asked to plot the frequency response of several different filters (high pass, low pass, and band pass) using an oscilloscope. My professor told the class ...
1
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2answers
116 views

Can a tank circuit store energy for a simple AC system?

If you take the circuit below, with the switch closed, assuming the Tank circuit is tuned to resonate at the same frequency as the source, then I would expect the tank to become charged, and the ...
0
votes
3answers
65 views

Can I use a switch rated as 250VAC 25A to switch 50VDC 25A?

I am looking for a switch that can handle 25A continous current, the voltage will be maximum 50VDC, most often about 46VDC, and it will be used to switch on two dc-dc converters that have no load ...
0
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1answer
43 views

OR switch for bathroom radio

Imagine there are two rooms. Room 1 has a light bulb and a switch to turn in on/off, and room 2 as well has a light bulb and a switch to turn it on/off. What I want to do is - connect a radio player ...
0
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2answers
108 views

Why do AC motors have various back EMF shapes?

I just saw in one of the threads that apparently, a permanent magnet synchronous motor and a brushless DC motor have different back EMF shapes. But why? I thought those two were exactly the same in ...
8
votes
4answers
2k views

Does AC Power have Polarity?

When I run 24VAC into a full wave bridge rectifier followed by a 220uF electrolytic capacitor to turn it into ~32VDC, the source has two wires. Does it matter in what order I connect the AC wires to ...
0
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2answers
70 views

Using DPST Relay to control AC Load

Below is the functional schematic that I am planning to use to control an AC load (air conditioner in this example with max current draw of 32A). Since I am still relatively new to mains power and ...
3
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2answers
105 views

How do I design a current transformer?

I want to make a Current transformer using toroidal ferrites to measure 220/50-60Hz AC current(40A max). Is it possible? And how can I calculate secondary turns count? Ferrite properties: H = 2000, ...
1
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1answer
116 views

Why there are live and neutral wires attached to house's wall sockets

If AC voltage is alternative, why there are two (Suppose there is no earth wire) wires attached to the wall socket: live or hot, neutral wires? And I think that in small home generators there is no ...