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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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High voltage input and low voltage capacitor in series safety

I’m working with a car battery that has a voltage drop when cranking the engine. As a result of this, the stereo restarts even though it was running already. To resolve the issue of stereo rebooting ...
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2answers
23 views

Using an AC rated light switch for switching DC logic level voltage

Would it be safe and within electrical code to switch logic level DC voltage using a standard AC light switch? I know high power DC lines can create arcing with a switch of that style but low power ...
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0answers
11 views

Automatic A-B 240 V switch [migrated]

My house is 150' long. The breaker box is at one end and the AC units are at the other end. I have a well pump at the same end of the house as the AC units are. I do not want to buy 8 ga uf-b ...
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2answers
34 views

Nonzero current at voltage zero-crossing when consuming reactive power

In a circuit that consumes some reactive power, the current waveform indicates current flow even when the supply voltage is at the zero crossing. This seems paradoxical since there cannot be current ...
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1answer
49 views

How is AC travel from a central to home? [closed]

Basically, in a alternating current the electrons moves back and forth really fast. From one atome to another? I'm wondering how the current can travel from a central to my home. I mean, for a cycle ...
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0answers
30 views

LV grid model with basic AC calculations

I have to analyze the voltages at each house: There is a lot of freedom to choose values for the cables and such, so it's not important at the moment. My concern is specifically how I should replace ...
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0answers
9 views

Is it OK to have a redundant path to earth? [migrated]

I have a home with separate flat on the grounds. Our system, in South Africa, has 230V live and neutral, supplied by the national grid operator through a distribution board, via isolator. It then ...
0
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2answers
61 views

Diesel generator consumption formula

I am working on a project to monitor a power meter parameters like voltage, frequency, current and so on and this monitoring for both AC and DC. For DC we are using Cummins diesel generator, now I ...
1
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3answers
88 views

What value of C should be added in parallel to make the circuit appear purely resistive?

I'm currently working through Cogdell's Foundations of Electrical Circuits and came across problem 4.39 d) as shown below: Earlier in the question I found the frequency-to-be-used as 43.3x10^3 rad/s. ...
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1answer
50 views

Complex Capacity

Recently we have been tasked to calculate the complex permittivity of a given capacitor. The formula suggests using the complex capacity of the capacitor. Which is what is getting me confused. I ...
1
vote
2answers
153 views

Why do I measure (almost) no voltage between 230V phase and my body?

The other day I was experimenting with a multimeter and checked the voltage in one of the electric plug at home. Without surprise I measured around 230V between phase and neutral and also 230V between ...
1
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2answers
162 views

A few basic questions about simple electric circuits

For beginning, sorry for my english and for long post. But maybe it would be useful for others newbies. I'm trying to understand basic things about electric circuits on my own, and at the moment I ...
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0answers
47 views

Wiring up single phase A/C motor

I have scavenged a small A/C motor and its capacitor from a broken washing machine. (There was another motor in the machine, which I discarded). Image given below. The capacitor has four wires, (PINK,...
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0answers
11 views

ATRU 18pulse winding topology advantages

There are three main winding topology when discussing ATRU's T-delta, Delta and Polygon The question is though... when to use which topology... The general approach I take when dealing with ...
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2answers
49 views

Is this a ac three phase motor with a dynamic braking control?

I am an electrical apprentice and this question popped up on my exam, and then again on an exam under a different topic, and I have to review it. What type of motor control is this? note: I ...
8
votes
1answer
150 views

Need help solving a problem with ac resonance circuits from my uni book

simulate this circuit – Schematic created using CircuitLab Okay I have struggling with this problem for some time and I cant figure out how to solve it. The circuit is in resonance! I tried ...
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2answers
56 views

AC line from inverter grounded to vehicle chassis

What happens if a hot line from an inverter powered by a vehicle battery contacts the vehicle chassis? This will form a circuit connecting the hot line from the inverter to the negative terminal of ...
0
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1answer
53 views

Understanding this TRIAC circuit

I have an inquiry about the circuit below: When a high signal is continuously given to the transistor, it enables the optotriac with zero crossing. The optotriac enables the power triac, and the AC ...
0
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1answer
32 views

How to determine the right trip point of thermal cutoff for 1/4 hp 3A 115V single phase ac motor

The Thermal fuse blew in my Ryobi DP102L drill press motor, while I was drum sanding. There were no markings on the fuse. The single phase induction motor is 1/4hp 3A (no load) 1750rpm on 115V AC, ...
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3answers
91 views

“Capacitor” for regulating AC line voltage?

I have an issue with my air conditioner. When it clicks on, the lights in my apartment dim for half a second. If this was a car audio system, I would just wire some large caps up to the battery to ...
1
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3answers
118 views

How an electrolytic capacitor survives in negative half cycle?

An electrolytic capacitor doesn't like higher voltage at its opposite terminal i.e higher voltage should only be at positive terminal as per convention.If that so how the capacitor survives in this ...
0
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3answers
125 views

Can a transformer have no secondary stages?

While disassembling the power for the spindle of my hobby CNC mill, I came across something peculiar which I think warrants a question on this site. The input is standard 220V AC. Phase 1 (brown) ...
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votes
2answers
60 views

In an audio circuit, with an LM386 chip - how does the DC electric power and the AC audio work?

I am currently putting together a simple audio amplifier using an LM386 chip. In the midst of studying how this chip works, and the proper circuit analysis behind it, I began thinking about how ...
1
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1answer
85 views

Measuring 200 volts safely

While I can measure line voltage safely, I need to write a procedure to have someone else measure the voltage. The load is pure resistive,and I want to measure the voltage across it, with a battery ...
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2answers
57 views

Thevenin Equivalent Network: How to treat Capacitor across 0v potential, with Dependent Sources?

We were given this question in our intro to EE course: Find the Thevenin equivalent network between points a and b for the circuit shown in the image below: For the short-circuit current, I redrew ...
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0answers
48 views

How to determine maximum power transfer and load impedance?

Edit: I realized my solution is invalid due to the dependent source. Upon further reading, I learned that only the independent sources get disabled, and \$R_L\$ transforms into a short circuit. ...
3
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2answers
58 views

Why is the 240VAC-12VDC giving both 12VDC and 26VAC as output?

I was using this adapter to power a 12VDC LED strip and felt electric shock from the output wire. When I measured the output with a multimeter, I found both 12VDC and 26VAC on it's output. What could ...
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0answers
37 views

When deriving the instantaneous power equation for an AC power system, I get different answers depending on how I model the V & I signals. Why?

When I define v(t) & i(t) like this: v(t)=VmCos(wt); i(t)=ImCos(wt-b), where Vm=Voltage Amplitude, Im=Current Amplitude, w=rotational frequency, b=phase shift between v and i relative to v. I ...
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3answers
97 views

Can I use an L7805CV with an AC input?

I am trying to switch a small water pump (for a pet fountain) according to the output of a PIR sensor. A couple of years ago I setup a circuit on a breadboard and tested it with the pump - it worked! ...
0
votes
1answer
78 views

Is it possible to Speed control this AC Motor? [closed]

This is a 230V AC Motor. One Phase. Is there a way to lower its speed? I have tested using fan capacitors which didn’t work. I tried a triac phase cutting settup, but it seems dirty, noisy (humm) ...
0
votes
1answer
51 views

How can I measure AC magnetic field using linear hall effect sensor with the arduino?

I have a SS49E hall effect sensor. I want to measure magnetic field in gauss using arduino analog output. I have a code for analog application but is this appropriate just for the dc magnetic field ...
0
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0answers
50 views

Differential Amp - Bipolar transistor

I can't get the same answer as they are getting.. Here is what I'm getting: $$ Acc = \frac{V_{oc}}{v_{ic}} = \frac{-R\beta i_b}{v_{ic}} $$ $$ i_b = \frac{v_{ic}}{r_{\pi+2R_0}} $$ => $$ A_{cc} = \...
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2answers
68 views

How to measure True Power (Not Apparent Power) consumption in Alternating Current using ESP8266-12F Microcontroller?

Currently, I am using the ACS712 current sensor module for measuring the peak current then computing RMS Current and thus the Apparent Power (Vrms × Irms = Apparent Power). Currently, I am not using ...
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2answers
64 views

Is it a safety issue to only bring the hot wire onto a board for mains switching?

I have a DC board that will be controlling my system. As part of my system, I need to toggle an AC motor on and off. At the moment, I have the hot wire off of my mains connection going into a terminal ...
1
vote
1answer
50 views

AC Line Testers

We've all seen AC line testers, with three lamps that diagnose the wiring of an electrical outlet (well at least in Canada/US). I'm (somewhat) used to the type that use neon bulbs, so I have two ...
2
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1answer
52 views

Is the Gummel-Poon model useful for explaining AC transistor amplification?

Let me be clear: By amplification I am talking about the process of boosting the strength of an AC signal. Thus, where the output power to input power ratio is greater than 1. Now suppose we have a ...
0
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1answer
54 views

Three phase RC unit

I found this component connected in parallel with an inductive load ( three phase coil used to disengage a mechanism ) the load keeps heating and burning after a while ( had to rewind it ) and no ...
-1
votes
1answer
61 views

What products can be used power LEDs from an wall outlet? [closed]

I am currently working on a project that will be a type of night light that plugs straight into a wall. What parts can I use to convert the wall outlet voltage into that which can be used by a couple ...
0
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0answers
46 views

Rectified X2 circuit gives 2 voltages depending on how the powerplug is connected to the wall (EU)

simulate this circuit – Schematic created using CircuitLab I'm trying to control a mosfet directly from a phase shifted 50Hz sine wave. But when I was trying to understand the voltage drop with ...
12
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10answers
3k views

How to check (with DIY methods) if an Inverter returns a Square or a Sine Wave?

I do not have an Oscilloscope, but I want to check if my 12V DC to 230V AC inverter does produce a sine or a square wave. Any way to verify that? I know how a sine wave and a square wave sound, so ...
0
votes
1answer
77 views

Can a Solid-State Relay Control AC Powered Fan Speed Via PWM

I'm working on a project where I'd like to control the speed of an AC powered box fan using a microcontroller. I am wondering if this can be accomplished by using a PWM output to control a solid-...
1
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1answer
21 views

Nest Protect gen 2 battery to POE

Hey all i am looking for some advice in how to go about my project with a Nest Protect gen 2. In my home i have ran cat6 wire to all 3 locations that require a smoke detector. These cat6 cables are ...
1
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2answers
68 views

Amplifying AC Current for Stepper Motor

I'm having troubles with a 3D printer. I need to change a motor for a more powerful one. For doing so, I 'll have to add an external small circuit to amplify the current but not the voltage given by ...
2
votes
1answer
103 views

I don't understand the windings inside my power drill. [closed]

I was curious about how my power drill worked and I disassembled it. I understand the general principles at work here but I don't understand why the winding is set up this way. I assume running ...
1
vote
2answers
106 views

How can a switch that is in parallel with a lamp affect the lamp?

I've come across a faulty kiln (pottery oven) and since the wiring diagram seemed simple enough I decided to try to find the fault myself. However I'm dumbstruck by a strange behavior of a lamp. The ...
0
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1answer
28 views

Solid State Variable AC

At work I often need a variable AC source and I usually use a large variable transformer which gives me anywhere from 1 to 300VAC. I do a lot of testing and was looking for methods to control the AC ...
1
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4answers
288 views

12V DC to 12V AC (50 Hz) Converter / Inverter for low loads (< 1A)

I am building a mobile Sound System powered by a car battery. I have a small mixing table that runs on 12V but it needs AC Power (50Hz) and won't work with DC (I tried that, with very weird results). ...
1
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3answers
36 views

Get 1,5U voltage on the transformer

I have a transformer with a midpoint that gives a voltage of 1U at the ends of its secondary winding. Can I, using only capacitors and diodes get a DC voltage of about 1.5U (but less than 2U)? If so, ...
5
votes
5answers
1k views

Safety of designing / using a plug that connects between two different wall outlets for increased voltage?

In North America we use 120V wall outlets, but sometimes 240V is needed for an application. Usually in a residential house in order to reduce load on the circuits they either run two different phases ...
0
votes
2answers
53 views

Where to get started in designing a 3 phase motor circuit [closed]

I am required to design a circuit that requires a 3 phase motor which can be spin at a range of desired speeds and times. I know this will require: A 3-phase motor An inverter to convert single ...