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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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
124 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
87 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
155 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
80 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
61 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 ...
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1answer
56 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
382 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
100 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
63 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
53 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 ...
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1answer
36 views

When do I have to use rectifier-inverter, and when is “dimmer circuit” sufficient in driving AC motor?

I'm trying to design a device that is to use a variable speed 1-phase AC motor. I still haven't decided upon power and other parameters of the motor. I have a few models to choose from, with "bigger ...
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8answers
401 views

Neophyte question about AC vs. DC (especially for powering a home)

Here in the United States the electricity grid is AC. I have heard that AC allows transmission of power at greater distances with less loss. However, with the advent of solar panels, it would seem ...
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3answers
429 views

Theory question about “j” imaginary unit (AC circuit analysis)

I have just started to learn about AC network analysis and have some questions about "j" (or "i" on my calculator), the imaginary unit. My book doesn't go into a great deal about this, and jumps ...
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0answers
45 views

AC Linear Actuator Driver for Arduino

For experimental purposes I want to build a 1-axis Polar Tracker and use an Arduino as a PLC unit. As I know it's necessary to use an Opto-isolator to prevent high-voltage from affecting low-voltage ...
0
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1answer
48 views

PSC motor driver circut using relay

I am working on a project in which i need to connect Permanent Split Capacitor(PSC) AC motor using relays as shown in the below block diag fig 1. I want to rotate it in both CW and CCW direction. It ...
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1answer
124 views

AC voltage gets mixed with DC

I am using ATS (automatic start) for my generator. Its programmable IC goes out of work after 2 or 3 days and I have replaced 3 ATS card. My card supplier says that you are somehow getting AC voltage ...
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2answers
65 views

Lamp flickers if dimmed up to an extent

I used circuit shown in this instructable to make an AC dimmer but everything goes fine if not dimmed much but then it starts flickering because of voltage fluctuation. ...
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2answers
93 views

How to select most efficient motor for generator?

First post. Please forgive me if this is a stupid question. This post can be broken down into two questions. I am building a bicycle generator, but am new to the field of EE. I am trying to select ...
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3answers
71 views

Which is good method for step down 50Hz, 230V AC

Which is low cost and safe for step down 50Hz 230V AC into 12V? Transformer or reactance or Regulator IC ? simulate this circuit – Schematic created using CircuitLab
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2answers
100 views

Measure 230V mains with 300V CAT II probe?

I need to measure harmonic distortions on a 230V 50Hz AC mains circuit. The Tektronix P2220 probes I have for my scope are rated for 300V CAT II when set to 10X impedance. Are these probes safe to use ...
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2answers
75 views

Phase Shifter: why is simple RC circuit's output 0 when phase is 90 deg?

I am rereading an electronics book (Fundamentals of Electric Circuits; Alexander) that says that the circuits or have the total impedance Z = R + jXc and that the phase shift is given by ...
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1answer
54 views

Elements of an AC expression

I am doing some coursework and research on AC theory and currently exploring the below expression: $$V= 100sin(100\pi t) + 60sin(300 \pi t - \pi/2) + 30sin(600 \pi t + \pi/2)$$ I need to find the: ...
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1answer
39 views

Connecting 3 phase ac motor

As far as I understand in delta connection 3 lines and earth is connected to the ac motor. But if wye connection should one use the neutral or earth to the motor?
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3answers
71 views

SPDT Relay with 8Pin

I needed a SPDT relay with 240Vac so I bought this relay from Maplin http://www.maplin.co.uk/p/15a240vac-spdt-miniature-relay-n07aw But I am heaving problem to wire this relay because it has 8 pins ...
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2answers
163 views

Using a shunt cap to create a delay - good idea? [closed]

simulate this circuit – Schematic created using CircuitLab C1 is a decoupling capacitor. If the input of U1 is experiencing undesired phase shift, can a decoupling capacitor correct the ...
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1answer
94 views

Bidirectional AC Switch with IGBTs

I came across a "IGBT Bi-directional Switch" on the web while looking for a solution to my problem of protecting a TRIAC/SSR from a short-circuit. Since TRIAC/SSR turn-off is not in my control, I'm ...
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2answers
103 views

What wattage solar panel required for AC 1000 watts

If my house load is 1000 Watts AC/220V, then 1000 Watts DC/12V solar panels is not enough. What wattage solar panel would be required for AC 1000 watts?
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3answers
484 views

How many Watts DC are equivalent to 1,000 Watts AC? [duplicate]

How many Watts DC are equivalent to 1,000 Watts AC? For instance, my load in AC is 1,000 Watts 220V. Then, how much DC watts would an equivalent load dissipate in 12V or 24V DC system?
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2answers
147 views

1n4007 Bridge Rectifier at 220 Volts AC?

So, I just started getting into electronics, and I have built a bridge rectifier using the 1N4007 diodes. So far I have been using this rectifier with a 24 volts step down transformer, but now I need ...
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5answers
2k views

What happens if a 240V appliance is connected in a 120V AC power supply?

I know that putting 240V through an appliance rated at only 120V would almost certainly damage it. But what if I connect an appliance rated for 240V into a 120V AC socket? Apart from degradation in ...
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2answers
37 views

Finding the non-zero value of ω, such that V and I will be in phase

Consider the impedance network connected to an AC voltage source in Fig. Q3(a). i) What is the network's equivalent impedance, in terms of ω? $$ ...
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4answers
106 views

Triple pole triple throw relay

I have a turntable which rotates cw and ccw. This turntable is rotated by AC synchronous motor of 230V. I want to be able to rotate the turntable with Arduino. For this reason I need to control the ...
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3answers
567 views

What is this AC source?

Below is a part of a schematic and I would like to understand each part of it. What I think is happening: This is being fed a 48V AC source These leads are a source and a ground? I'm not sure ...
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1answer
114 views

Running brushed universal motor at different frequency than designed

First, the end goal is to run a power tool (namely a Dewalt DW734 thickness planer) designed for 110V at 60Hz at a country where the power is 220V at 50Hz. The motor is a brushed universal motor, ...
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1answer
65 views

DC motor spun clockwise then counter clockwise creates AC current?

I am making a generator with a DC motor but the style of turning the rotor would be clockwise and then counter-clockwise, and I would want to capture as much current as possible so I hope it could be ...
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2answers
91 views

AC amplifier with fixed output range?

Lets say I have a sine frequency sweeping circuit (1kHz-10MHz) that goes down in magnitude, from say 3V to ...
2
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1answer
79 views

Device to switch a 220VAC/40A resistive load

I need to switch a 220VAC/40A resistive load. I only need on/off switching, no phase control. I would like to avoid mechanical (moving parts) components if at all possible because of reliability ...
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0answers
96 views

Mosfet as a Switch

I have created 2 circuits using altium designer as shown below: After simulation here is what i have for the left circuit: Right circuit: Basically, as you can see in the first circuit i have 2 ...
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0answers
38 views

LED bulb that works on both 64 volt DC and 110 AC

Can anyone advise on a reliable/cost-effective way to modify a screw-in LED light bulb so it will run on an AC power supply that has a battery backup where DC is provided in backup mode (this is for ...
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1answer
122 views

What capacitors do when it is connected in Series and parallel to a AC input

I have seen in many circuits the capacitors are connected in series and parallel with the AC line. What the capacitor actually does when it is in series and parallel. I know capacitors passes AC ...
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4answers
441 views

How can a faulty USB charger kill you?

This question relates to this incident here. Where a women in Australia died from a faulty USB charger that allowed the full 240v mains voltage through the USB cable. Now from my understanding you ...
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3answers
104 views

Stable power for LED from 5.5 to 7.5V AC

About a year ago I posed the question "Making 12V DC from 6V AC". Since the conversion from AC was going to be problematic (for me), I tackled the tail/brake light first, because working with the 6V ...
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1answer
64 views

Question on capacitive circuit in practice

If we were to build a circuit, let's say with a power source of 120V AC going into a transformer which steps that up to 10kV @ 30mA, the output of which would be connected to a capacitor with a ...
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1answer
98 views

High voltage/current design on PCB

I am building a circuit that allows me to control a set of light (more specifically Christmas lights you see in supermarkets) with relays (AQH 2223). My idea is to have the controller input on one ...
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5answers
448 views

Why do electronic circuits need their power supply to be DC, or rectified AC?

I'm pretty sure the answer to this should be obvious - even to me ... It's been a while I've been reading and attempting to construct simple electronic circuits. The supply almost always is either ...
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1answer
87 views

Why would we need to ground an AC source?

I'm new to this field hence this weird question. Why would we need to ground an AC source? Why wouldn't it be enough to have just one pole to get an AC current going? I understand why it wouldn't work ...
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2answers
77 views

Can I make pulsing light using AC as source, a diode and a LED?

I'm new to this branch of physics hence my stupid question. I know that diodes are used to make current flow in only one way. If I connected an AC source to a diode and the diode to a small light ...
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2answers
111 views

Way to measure AC power in 2 wire cable

Is there a way to measure AC power/current delivered through 2 or 3 wire cable? I know that from Ampère's Law the total current of both wires is zero, but is there a way to measure power in cable in ...