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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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 ...
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0answers
12 views

How can I control an IR204E in a PK543A to remotely operate this apartment door buzzer? (What relay do I need?)

My apartment door 'suite station' (buzzer) is a TekTone IR204E (pdf). It has an option for talk, listen, and open door. It contains four wires labeled 1, 2, 3, and X. My research leads me to believe ...
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0answers
29 views

How to control a bulb operating on 230v using a switch operated at 5v

Hello Electrical engineering community, Maybe this is an easy question to answer but I am new to this so definitely need assistance. I want to control a bulb which is driven via 230v AC mains using ...
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0answers
53 views

Circuit for finding engine RPM using the magneto's coil ground wire

I'm looking to see if there's a solution without using a microcontroller to find the engine RPM (perhaps spark frequency is a better term?) using only the magneto's coil grounding wire. This wire ...
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1answer
33 views

How can I use the presence or non-presence of an 120VAC input to actively discharge a bias power rail?

I'm designing a power supply that has an input of 100VAC to 300VAC. On the primary side on the main transformer, I have a 15V rail to power the control chip (a FAN6920) and a gate drive chip (a ...
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3answers
95 views

Is Faraday's Law not working?

Faraday-Lenz's law was easy when I was in 12th standard. But it became more complex when I jumped to Engineering. Recently when I was studying about inductors and how they oppose changes in currents, ...
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1answer
38 views

Operation of a Growler to test armature shorts

Can someone explain to me how a Growler for testing electric motor armatures works please? I have obviously read the Wikipedia Growler page but it is still foggy. So the growler unit acts as the ...
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1answer
35 views

What is the name of the IC that runs a low-harmonic power supply?

I'm interested in building an AC/DC converter for low-harmonic applications. Single-phase AC input, followed by a rectifier and a PWM-controlled boost converter. I know there are ICs which are ...
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1answer
73 views

Charger light circuit [duplicate]

I have a charger light. It gets charged by 220V AC supply. It can light 5 LEDs. I know that it needs to make the supply 220V AC to DC of lower voltage nearly 5V to 10V. Then it can charge the small ...
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1answer
55 views

Is there a limit of series connected LEDs when driving them with AC?

I want to drive as many as possible LEDs with AC grid voltage. Assuming that there are \$n\$ LEDs connected in series, the voltage drop on the will be \$2.2nV\$. Then the voltage on the capacitor ...
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3answers
69 views

Can I use this relay for DC

http://www.dx.com/fr/p/ssr-25da-25a-solid-state-relay-white-134494#.VDmPWPl_uap It says AC output but how can this transform DC to AC ? Shouldn't this act like a switch ? If my circuit is DC and I ...
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3answers
65 views

Effect of non-inverting op amp on the AC and DC components of the input

I was wondering what the effect of an op amp like the one in the image below is for an input signal such as \$0.5\sin(2000\pi t) + 0.5\$ V? Are the DC and AC components amplified with the same gain? ...
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2answers
200 views

Understanding cause of arcing in AC filter circuit

I have an induction hot-plate that one day blew a fuse in my distribution panel when plugging it in. (With the obligatory smoke from the device of course...) On visual inspection, only the AC filter ...
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2answers
138 views

Can I use DC resistor in 220 V AC circuit?

Can I use DC resistors as AC resistor? If yes, is there any problem interfacing with it? Please recommend AC resistors for working with 220 V AC 50 Hz.
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3answers
69 views

How and why is a magnetic field transmitted with alternating current?

I apologize for the basic question (or if it is incorrect in its assumptions,) but how does one account for magnetism in alternating current? If I generate alternating current to a motor, why do my ...
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0answers
53 views

How to create a 120V-175V Variable Frequency Generator

I am dealing with a system that requires me to drive a capacitive load at 120V-175Vrms, AC square/sine wave at two frequencies: 50Hz and 2000 Hz @ Ipeak = 100mA. I am currently trying to find the best ...
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1answer
64 views

AC source in parallel with resistor problem [closed]

For an AC source of for example +-12 V, can a connected resistor at any instant, have 24 V across it? Because my textbook has a problem in it involving such a source and says (hint: consider the ...
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2answers
76 views

Controlling AC mains using Arduino and removing control easily

I am planning to for an Arduino to read status of a switch, and accordingly switch on and off AC appliance, for a demo purpose. I want to add a feature to it of easy recovery to manual switch control. ...
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1answer
51 views

AC switch & power supply reverse engineering

Below is schematic of self-powered(by passing little current not enough to operate) switch reverse-engineered from PCB. simulate this circuit – Schematic created using CircuitLab Zener ...
0
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1answer
78 views

Detect alternating current using one contact only and arduino analog input

I am trying to setup an arduino so it can detect an AC where it only has access to one pole. (kind of like these "electricians screwdrivers" that you put in one of the connections of an electric ...
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0answers
158 views

How to determine phase and neutral on a wall outlet? [migrated]

I live in EU and an outlet at a home has two holes (230VAC), no common ground. I want to determine what hole is phase and neutral. Is it possible to do that by using a multimeter? When I measure ...
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1answer
139 views

How to replace bulb with LED in a PWM circuit (car)?

I want to replace a light bulb in a Peugeot 308 SW with a LED. The bulb works (lights) normally, but the LED blinks. I thought they are controlling the bulb in alternative current but my digital ...
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2answers
63 views

Wheel speed from Shimano dyamo hub using arduino

I'm trying to figure out a way to extrapolate wheel speed from the Dynamo hub I just purchased. I outputs 6V 3W AC, and I would like to potentially measure it using an arduino if possible, I' assuming ...
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2answers
57 views

Actual/theoretical benefits of round or flat outlet prongs

What might be the reasoning for European connectors having rounded prongs while USA and UK connectors are primarily flat pronged? Please correct any mis-tagging.
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0answers
58 views

High voltage low voltage switching circuit

I am working on a project which involves switching of a point from AC mains to low voltage ground when I start my low voltage circuit. Till now have come up with following circui. 1) Point A in the ...
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1answer
28 views

Replacing an AC power supply that is 2 volts higher than the original but has the same current rating [duplicate]

I have an audio mixer that requires an AC 16 volt 1 amp external power adapter. I need to know if an 18 volt 1 amp AC external power adapter would work without damaging the audio mixer?
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0answers
47 views

Total current through a parallel ac circuit

I want to calculate total current entering the circuit in this question (10.15). Please help me with this and I would be obliged if someone give a detailed explanation on this because I guess simple ...
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6answers
2k views

What makes mains voltage safe in homes?

When I started learning about electrical engineering, one of the most important safety guidelines that I learned was that voltages over 36V can be dangerous. As my circuits professor put it, 120VAC ...
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1answer
46 views

Equivalent sequence/stepper relay to “FINDER - 20.21.9.012.4000”

I am currently looking at this relay: FINDER - 20.21.9.012.4000. Which is step relay, that makes contact AC output active with coil input DC (12V) [which i need]; and disconnects output when coil is ...
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4answers
2k views

What are the highest DC and AC voltages or currents that can be considered as safe?

By safe I mean safe for us when we touch a wire that is not insulated. I have heard that human body resistance is normally 50k Ohm when dry and 20K Ohm when wet. Therefore, these voltages or currents ...
0
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1answer
33 views

Convert a non-isolated converter to an isolated converter

Is there a way to convert a non-isolated converter(such as R-78C5.0-1.0) to an isolated converter.
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3answers
73 views

Simulate RF transmission lines at Low frequencies

I would like to simulate RF transmission lines in how they propagate, and how impedance mismatches at the end of the transmission line cause reflections and power transfer does not work. It would be ...
0
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1answer
37 views

triac DC ground and AC live

In this example of using a 3Q triac, could the AC voltage flow into the DC terminal?
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2answers
82 views

Using an AC plug for DC current

If I have a plug that is rated 10A @ 250V AC, is it safe to assume I can use it at 10A @ 12V DC? Could it be used at higher current or should its maximum be lower for that matter? Thanks!
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1answer
69 views

Current “jumps” from one wire to the other

I have cable with two 1.5mm wires in it. Why does my test light show voltage in both wires even though only one of them is connected to 220V AC grid. // Also there are old cables with metal jacket ...
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2answers
113 views

Why does AC Current exists? [closed]

I need to know why does AC Current exists? And why not only DC current exists? Most devices needs DC current. I know that DC current is much dangerous then AC current. because of it is alternating ...
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0answers
37 views

Winding factor calculation for three-phase two-pole machine

Calculate the winding factor in phase a winding if the number of turns in the four coils in the two outer pairs of slots is reduced to six, while the number of turns in the four coils in the inner ...
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1answer
101 views

How much current actually passes along household neutral?

My home has 3-wire single-phase supplied from the power company (Massachusetts, US). Red and black are separated by 180°. Both are 120 V from neutral (white). And in my electrical panel, neutral ...
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1answer
118 views

Calculate current using compensation

simulate this circuit – Schematic created using CircuitLab Okay, first I'd like to apologize if this question seems stupid, but I'm preparing for an exam, and don't know how to solve this ...
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4answers
160 views

How do you remove negative voltage from a sin, triangle or square wave?

I need square wave without negative voltage. Considering a source which produces square wave (could be function generator or from other circuits) has no ability or I don’t have the control required ...
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2answers
1k views

AC to DC without transformer. How does this thing work?

I disassembled a Chinese-made flashlight and found they use just capacitors to bring down the voltage instead of a transformer. They are using it to charge small lead-acid battery. My question is how ...
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2answers
105 views

Using a DC voltage as the base for a transistor to amplify AC Voltage

I'm a little new to electronics, particularly transistors, so I don't know a lot of the different types and inner-workings of them. I have a diagram which, hopefully, will gradually increase the ...
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2answers
158 views

What's the name of this circuit, and how does it work?

I was reading Hack Into a Timer AC Socket and when I got to this paragraph: The design firstly have a RC buck? (not sure how to call correctly in English) circuit to step down the voltage from ...
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2answers
117 views

Difference between DMM and oscilloscope measurements

I have a 220 - 14 V transformer, but when I hook it up to oscilloscope or DMM they show different values. DMM shows 11.8V and oscilloscope shows 17.2. Ok, this is cheap Chinese transformer, so it can ...
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1answer
77 views

Help Running Xmas Lights On 6V AC Flying Saucer

first time here. First I will explain what I have then ask for a solution to my problem... I have a fiber optic UFO display that has a slow turning electric motor to revolve a color wheel to light ...
0
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1answer
57 views

AC power analysis

A transformer rated at a maximum of 25 kVA supplies a 12-kW load at power factor 0.60 lagging. What percent of the transformer rating does this load represent? How many kW in additional load may be ...
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3answers
535 views

Aren't non-polarized plugs a little dangerous? Why still use them?

Sorry if there is an answer for this kind of question somewhere. I can't find it anywhere. Take a look at obvious toaster example: If you live in Europe and have non-polarized plug and a toaster (a ...
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3answers
109 views

What are the big plugs for that you find on high demand devices in North America (120V-Areas)?

Talking about AMEA socket system and 120V. High power demand devices like A/Cs do have bigger plugs with some switches on them. What exactly is their purpose? Seems like a fuse but isn't the socket ...
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2answers
82 views

Full wave doubler difference and connection of neutral and phase

I'm testing a circuit for creating am unregulated "HV"DC source. The circuit is like this: simulate this circuit – Schematic created using CircuitLab The example I'm using uses a Variac ...
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1answer
82 views

Connecting common of relay with main cable of 240VAC

I trying to control my turntable switch with Arduino. This is a toggle switch with 3 wires one wire is for CW rotation the other one is for CCW and the other cable is main with 240VAC. I am using this ...