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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81 views

How to switch separate circuit from doorbell?

My doorbell rings as long as somebody pushes the button. I measured 10V AC at the bell when it is ringing. Now I would like to use this AC voltage to switch another circuit. How can I achieve this? ...
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0answers
33 views

AC relay parallel [closed]

Is it possible to connect relay in parallel on AC circuit? I will describe better the problem. In my domotic solution I have a wireless/RC circuit to control a wall socket. It has a transformer to ...
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2answers
27 views

Phasor math for balanced 3 phase circuit

Are there any mathematicians in here? I am currently reading my ECE text's chapter on AC machines and i referred to some material in the chapter that first discussed AC circuits. In the photo below ...
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2answers
63 views

Use of 230VAC overcurrent protection for 24VDC circuits [closed]

Is it right to use 230VAC overcurrent protection for 24VDC circuits? Why? Why not? For example: http://www.tme.eu/en/details/a9f05120/circuit-breakers/schneider-electric/ I saw some machines which ...
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2answers
47 views

What happens with voltage phase on the resistor and capacitor in AC circuit?

I'm currently studying AC circuits and I find it difficult to understand phase differences between voltage and current on different components. For example, let's look at this circuit: And here is ...
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1answer
49 views

An SPDT switch using TRIACs

I need to design a circuit that implements an SPDT switch using Triacs and Optoisolators. Currently I am implementing this with two pairs of Optoisolated Triacs with one having inverted signal from ...
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2answers
42 views

Am I correctly concluding that these two AC/DC adapters are interchangeable [duplicate]

I'm in the US with 120V mains. I have a "heavy" style AC/DC adapter (weighs a pound or so) and a lighter one (weighs a couple of ounces) which came off a 1TB Seagate NAS. Can I replace the heavy one ...
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1answer
79 views

How do I stop coiled (telephone) wire blocking signal?

This circuit is working just fine if the output signal uses a straight wire, even if it is a very long wire with say a 1K resitor added to the end of it. However, the signal does not get through when ...
3
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1answer
62 views

How can I create two ac signals with a voltage controlled phase offset?

Is there a fairly straightforward analog circuit (resistors, capacitors, transistors, etc) to generate two sine waves of the same frequency and introduce a relative phase offset between them? So I'm ...
0
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1answer
38 views

Interfacing a mains referenced AC measurement circuit with a PC

I need to connect an AC mains referenced measurement circuit with a notebook and I wanted to know if its safe to do that without an isolator. The measurement circuit primarily steps down AC voltage ...
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0answers
35 views

Energy meter measuring AC power

I am investigating building an energy meter probably using an Arduino and trying to understand the main principle of operation. We have a solar installation on our roof and already have meters for ...
1
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1answer
49 views

When calculating the voltage in an AC Circuit, I get a different angle from the correct answer

Problem I'am trying to calculate v2 from the circuit below, but my answer, 9.81cos(1000t+166.64°) mV, has a different angle from the correct answer, 9.81cos(1000t-13.36°) mV. My approach I tried ...
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0answers
51 views

How to wire capacitor start ac motor

I have a motor with a blue, yellow, black, and orangish wire coming out of it and I'm trying to figure out how that should be connected to power based on the wiring diagram on the side of this motor. ...
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1answer
39 views

How to wire this Buffton motor

I bought this motor at a scrap yard and would like to wire it up for 120 volt power. There are 5 wires coming from the motor, a black, white, ground and two yellows. One yellow is numberer "2" and ...
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0answers
64 views

problem with igbt driver when turn on ac voltage supply

I 'm trying to make project "Design of a single phases AC-AC", but when i turn on voltage supply 220v/50hz, igbt and fuse are immediately dead, i don't know why? i had lost more money for it, can you ...
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1answer
69 views

Will a 0.5V difference in output damage the device? [duplicate]

I have a speaker adapter, with an output rating of AC 11.5V ~ 1600mA, which I am looking to replace and the only replacement I can find has a rated output of 12V ~ 2000mA. I've read somewhere that a ...
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0answers
58 views

Blower (Fan) Capacitor on Water Cooler

I've got a water cooler that has a centrifugal blower inside it. The blower fails to start most of the time, but I've verified that the motor works because it starts with a slight nudge. A slight ...
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0answers
57 views

Circuit to measure impedance

I'm trying to make a circuit to measure impedance through a FRDM-KL25Z board. The basic idea is to use two signals to calculate the phase shift between them, and use a impedance divider to calculate ...
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1answer
64 views

How to 'average' a sine wave of RMS values?

Lock-in amplifiers (Stanford Research Systems 830) display sine wave signals in RMS values SR830 Manual (page 3-3). One can use the internal buffer to rapidly measure a signal, storing up to 16000 ...
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2answers
87 views

How do I prevent backfeed through contactors when joining 3 x 230v ac circuits all single / same phase

I am working on a project to safely combine separate power circuits into one. Its to do with using available power instead of renting mobile generators. The problem is that the 'magic box' has ...
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0answers
26 views

Resonant RC Series and deriving equivalent circuit

How is it that this is equivalent? Assuming all transients have died out. vi = Vcos(omega*t) The fake input was defined as: \begin{equation} v_{cp}^\sim = \frac{V_i}{1+j\omega_1RC} e^{j\omega\\_1t}...
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2answers
42 views

Calculating true power of a predominantly inductive load?

I'm stuck at this problem, which doesn't seem to be so difficult, but, I guess there is some basic stuff that still confuses me. So, if we have a load represented with complex impedance \$Z=30+j40 \ \...
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6answers
96 views

Controlling the frequency of AC used to energize an electromagnet

I am trying to build an electromagnetic pendulum which essentially has a pendulum arm with a permanent magnet at its end which is 'kicked' by an electromagnet placed at the mean position to drive the ...
0
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2answers
68 views

How to detect that a voltage source is not powered? [duplicate]

I need to detect when the switch SW1 is on and when it is off, and this input has to be sent to a GPIO of a microcontroller. I have no idea how to implement the circuit required to achieve this goal, ...
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0answers
7 views

Explain voltage readings on NEMA 10-30 socket [migrated]

The clothes dryer in the garage is plugged into what appears to be a NEMA 10-30 socket (receptacle). Reading the voltages on the socket with a multimeter, the voltage between the two diagonal ...
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3answers
80 views

Is this a good method to detect 120VAC

I need an embedded micro controller to detect some 120V AC signals, I decided it would be safest and most likely the best to use an opto-isolator. Below is my circuit, I rectify the incoming 120V and ...
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1answer
72 views

Using an AC drill motor with DC?

I have this motor from drill that is powered from AC. Is possible to use the motor with DC current?
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3answers
79 views

using 50hz frequency in ac current [duplicate]

Why we use exactly 50 Hz and 60 Hz, instead of 100 Hz or even 400 Hz 1-is it for light 2-is it for the speed of ac motors Can I use a machine that work in 50 Hz ac network, in 60 Hz network This ...
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0answers
49 views

programmable AC voltage regulator

I have a testing setup where we have a manual voltage regulator that takes 230V AC input and outputs 50-230V AC. this goes then through a Power meter, then feeds a heating element. I use this to test ...
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1answer
67 views

Understanding AC to DC conversion

I am able to see following specs on my laptop adaptor. 65 W Input AC: 100 - 240 V, ~1.5 A, 50 - 60 Hz Output DC: 19.5 V, 3.34 A My HP laptop: I am bit unclear ...
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3answers
67 views

Trying to make an AC 3 phase motor run as smooth as possible at low speeds.

Is there a benefit in smoothness of rotation by increasing the outer rotor magnetic poles? Is there a rule of thumb for a 24 slot core vs number of magnetic poles?
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1answer
60 views

Average of AC signal measured with oscilloscope

I'm wondering why the oscilloscope displays that average rectifier ripple voltage value measured in AC mode is higher than zero. Moreover, the minimum value happens also to be higher than zero. ...
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1answer
71 views

Wy are speakers rated by impedance instead of inductance?

Audio speakers contain coils which product sound by vibrating a cone. Why are speakers rated by impedance instead of inductance?
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1answer
33 views

Voltage Spikes in AC voltage Controller

The diagram above shows my circuit. It is actually an AC Voltage Controller with PWM controlling the output voltage and a 1:2 transformer stepping it up to 230V. A 1.8uF capacitor is used as a filter ...
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0answers
34 views

24VAC Power Pack Peak to Peak or RMS Voltage? (For Split Rail Power Supply)

I'm designing a regulated, current limited split rail power supply for \$\pm12VDC\$ and was thinking of achieving this with a 24VAC input plug pack/wall wart. I implemented the power supply with ...
0
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1answer
21 views

DC consumption translation to AC consumption

I've a battery charger that can output 9v and 2.5A and I use full power from it that is 22.5W. Can I translate this power consumption from DC to AC current? My AC is 220V 50Hz, so I'll consume 22....
0
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1answer
79 views

How to use arduino nano to switch an 230V AC motor on/off?

I want to switch on and off an 230V AC motor with a relay what is controlled by an arduino nano. The on time and off time would be able to set by a 3-position slider switch. So would be 3 different ...
1
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1answer
111 views

Relay Feedback Problem

I am a computer science student working on a project for my Diploma and I am building a DIY PDU, I thought building something would be a lot funner then programming a website like 90% of the class ...
1
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1answer
51 views

Plug from laptop AC adapter was broke [closed]

When I tried to plug my AC adapter was broke. Here you can see it: It's only the wire so I can replace it without any problem from my AC adapter. But my question is: Can I use any wire (while it ...
0
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2answers
42 views

3 phase AC circuit supply potential difference

How can the line voltage be 220 V when in actual line voltage is the potential difference between 2 different lines. For ex:- Vry= 220 V. And why do we divide it by root of 3 to get phase voltage. ...
0
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2answers
51 views

Doorbell to buzzer with relay and AC to AC transformer

I have the following buzzer and want to use it with a switch by the door. Would the following configuration let this work or are there crucial parts missing? simulate this circuit – ...
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3answers
88 views

Power draw from 120V AC Outlet

According the the following link, a minimum of 4800W is drawn from an electric stove when all burners are turned on: http://www.ehow.com/how-does_5179441_many-watts-electric-stove-use_.html. I'm just ...
6
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4answers
2k views

Why are motor capacitors huge in physical size even though their values are in uF range?

When I see some teardowns of single phase induction motors on the internet, I see their capacitors look like: Why are they that big in size compared to other caps, even though their value is in ...
0
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2answers
96 views

Why does my Kill-a-Watt read Power of only half the Voltage times Current?

My Kill-a-Watt is displaying that its output is 120 V, 0.16 A, and 10 W. I'm confused... I thought P = V × I from basic EE. Why do I see only half the expected value here? (This is a USB charger, ...
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votes
1answer
64 views

13.8v from transformer

I have an old CB that looks like the Kraco 2555FM and that takes 13.8v. I'm not sure for certain but that is what I can gather from searching the internet. I guess my CB does take 13.8v as well. I ...
2
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1answer
32 views

Obtaining Anderson's Bridge Balance Equation

I'm trying to learn Anderson's Bridge Balance equation.I dont know how this value is obtained Why are they equating the voltage drops across branch one and the sum of the voltage drop across ...
0
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2answers
78 views

In a single-phase transformer output, which-wire would be phase, and which-one would be neutral?

In a single-phase transformer input, one wire getting entry as live, another as neutral. But what would be in case of its output? In output, which-wire would be phase, and which-one would be neutral? ...
0
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1answer
47 views

Different amperage with a normal and a hook Multimeter?

I am measuring the electric power (P = VI) in a gear-motor. I measure it of two ways. One way is measure with a multimeter the resistance of the motor, then with V=RI, I measure the current, then I ...
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2answers
59 views

Why is DC used in circuit devices? [duplicate]

Why do circuits mostly run on a DC current? I understand that electric motors use AC but things like my laptop operate on DC. Are there another advantages to AC current that made it the standard ...
0
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1answer
18 views

AC voltage regulator in parallel

I have two voltage regulator which works on ac. They are both the same model and provide a maximum power of 3000w. I would like to plug their outputs together to make a 6000w total voltage regulator. ...