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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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 ...
0
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1answer
39 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 ...
6
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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
29 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.
0
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3answers
62 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
31 views

triac DC ground and AC live

In this example of using a 3Q triac, could the AC voltage flow into the DC terminal?
1
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1answer
57 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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0answers
42 views

AC / DC Axial Fan power usage VS. performance

My question is about Axial fans. Specifically, similarly sized, built and performant AC / DC axial fans. Given 2 fans from the same manufacturer which can push very similar amount of air, with ...
1
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1answer
66 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 ...
-3
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2answers
104 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 ...
0
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0answers
26 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 ...
0
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1answer
87 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 ...
0
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1answer
84 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 ...
1
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4answers
139 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 ...
13
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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 ...
1
vote
2answers
97 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 ...
0
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2answers
157 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 ...
0
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2answers
87 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 ...
0
votes
1answer
66 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
votes
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 ...
3
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3answers
425 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 ...
0
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3answers
104 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 ...
0
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2answers
69 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 ...
1
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1answer
61 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 ...
0
votes
1answer
37 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 ...
8
votes
8answers
409 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 ...
5
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3answers
454 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 ...
0
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0answers
53 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
53 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 ...
0
votes
1answer
127 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 ...
0
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2answers
69 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. ...
0
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2answers
103 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 ...
0
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3answers
75 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
2
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2answers
108 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
81 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 ...
1
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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: ...
0
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1answer
44 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?
0
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3answers
78 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 ...
0
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2answers
165 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 ...
1
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1answer
149 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 ...
0
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2answers
110 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
497 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
179 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 ...
6
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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 ...
0
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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? $$ ...
1
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4answers
128 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 ...
2
votes
3answers
568 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
129 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
80 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 ...
0
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2answers
92 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 ...