Mains electricity, typically a higher voltage AC waveform used to deliver electrical power to households. In North America 120V, 60Hz, in most European countries 230V, 50Hz. What most people will plug appliances into.

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Wired vs SMD resistor on 230V optocoupler input

For circuits similar to the one below, we used large wire resistors with proper power rating in our past designs. The question came up, if it would be a good idea to replace the resistor with SMD ...
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55 views

resistive braking for induction motor?

It occurred to me that since single-phase AC induction motors can act as generators, it might be possible to brake an induction motor with a resistive load. The basic idea is that when you want to ...
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2answers
60 views

Looking for a simple way to inject a signal on 60Hz Mains line

Okay, so I'd like to be able to inject a really simple signal on top of the 60Hz AC Mains. It doesn't have to contain any data per se, just a simple signal to trigger a receiver on the same ...
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64 views

Mains isolation is mandatory for UL/CE/CSA compliance and other certification?

I have a design with a non user accesible low voltage section. Is mandatory to do mains isolation to pass succesfully UL/CE/CSA despite my low voltage section is not accesible for user?
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55 views

Arduino Dimmer Shield Schematics Interpretation

I've read so much about Thyristors, Triacs and Rectifiers on the last days that I'm almost understanding my schematic, but I'm not there yet - I need some help. Overview: I'm making a home automation ...
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113 views

Question on Mains return current

Since the neutral wire is grounded at the circuit breaker panel, I am confused as to whether current actually flows along the neutral back to the service head? If not, then what actually absorbs the ...
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7 views

This light won't turn on [migrated]

So, I was around my partners house the other day and they have a light on the landing that does not work - I don't think it has ever worked since they moved into the house and being an electronic ...
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2answers
72 views

unexpected power supply behavior

I am using this large 24V power brick (rated for 9.2A) to power a small circuit (an arduino controlling some RGB LED strip, drawing less than 0.5A). If I physically pull the plug out of the wall, the ...
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74 views

Differentiate between mains and a generator

This question is related to: Can I differentiate between a UPS, Generator and Main sine wave using a micro-controller? I'm only interested in the difference between mains and the generator. ...
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28 views

What's the typical harmonic distortion on the secondary side of a distribution substation?

What's the typical harmonic distortion and waveform found at the low-voltage side of an urban substation (I.e: the aggregate of appliances and secondary distribution system impedance)?. If you can ...
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2answers
51 views

DIY Isolated Power Strip?

Would it not be ok / safe to take a surge protector style power strip, cut the mains cable in the middle (or maybe slice it open and just fish out the load and neutral wires so that the ground wire is ...
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88 views

Need circuit to Switch 240v a.c. mains with 3v or 5v

I have the IRFP460 power transistor which if I understand correctly can switch 20A/500V on 20v input. I am wondering what a circuit design would look like that would allow me to either (a) switch ...
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91 views

Plugging in an oscilloscope in a land of non-grounded outlets

Background: I have only one outlet in my house that remotely approximates a proper equipment grounding conductor (it's bonded to the mains ground point via the armor of 50s vintage AC, which is better ...
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3answers
136 views

Resistor calculation

I'm still new to electronics and I am trying to do a calculation. Say I have a 100 Watt bulb that runs at 120V and my source is 240V. I know the bulb will blow but my question is: if I wanted to put a ...
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2answers
551 views

Multimeter into wall sockets

If you placed one of the multimeter's probes into the hot slot of the wall outlet and touched the other probe to your skin while grounded, for example to some dirt outside, would you get bitten by the ...
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8answers
943 views

Why are we not always isolating the mains supply?

Something struck me: to protect people, the neutral of the supply is connected on the supplier side to Earth, so that leakage through ground is detected when for example someone touches the phase ...
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2answers
200 views

If a large AC generator is overloaded, will it lose frequency or voltage?

If a large AC synchronous generator, like one from a hydro dam, were to receive overdemand from the grid, would it start losing frequency or losing voltage? I know they have several safeguards to ...
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2answers
141 views

Turn a mains light on slowly

I've been looking at creating a simple circuit to slowly turn a halogen daylight bulb on over about 30 minutes as soon as power is supplied to simulate dawn. I've got a 240VAC 42W halogen bulb that ...
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3answers
112 views

Is the white wire carrying any electrons

I don't understand why neutral in 110v , does it carry any current ,does the load like the light reduce the current
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1answer
90 views

Is it possible to connect a UPS in parallel with the mains?

Short version: When a UPS is plugged in to the mains, is it possible to plug the UPS output back to the same mains? Will that work as an emergency power backup for the mains circuit? Longer version: ...
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27 views

Fan needs full power to spin up; would then like to have to run off a speed control

Fan in question: http://www.amazon.com/Active-Air-inch-In-Line-Fan/dp/B002JQ4N92 Fan speed control: http://www.amazon.com/Lutron-DVWFSQ-FH-WH-Single-Pole-3-Way-Control/dp/B000MAVHTG The lowest ...
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2answers
60 views

Is it safe to connect battery in series with wall adapter?

Is it safe to connect a battery in series to wall via adapter? I have an AC adapter which gives me 10 vDC from the wall (220 volts). I've measured the adapter and it outputs 10 vDC. I have a 3 volt ...
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80 views

Can I power a 230VAC fan with 220VAC?

Here's the fan I want to use: http://www.nmbtc.com/pdf/acfans/4715ms.pdf The 220VAC model costs $70 while the 230VAC model costs $17. Can I safely use the 230VAC model in China, where the mains ...
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1answer
49 views

Making conducted EMI measurements in the presence of building-wide ground-fault protection for personnel?

As is documented here among other places, the Line Impedance Stabilization Networks used to make measurements of conducted EMI as per CISPR 22, FCC Part 15, and suchnot contain large line-to-ground ...
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4answers
124 views

Providing house wall switches with 3.3v/5V supply?

It's a bit non-technical, but I'd love to hear the opinions of the pros. I'm trying to figure out what is the best way to connect my home's wall switches (lights, etc.) to 3.3V/5V. The plan is the ...
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447 views

How can a light dimmer in series modulate a load?

Not after a full breakdown of how this specific light dimmer works, but rather how a device in series can control a load. A light dimmer has the following wiring diagram. As you can see, the light ...
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56 views

Inverter using battery even when mains power supply is on [closed]

All the points connected to the inverter are using battery power even when mains power supply is on. When inverter is turned off , those points connected with the inverter have no power, not even ...
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2answers
56 views

A relay for each terminal (live and neutral)

I'm investigating a control circuit that switches a heating element. From what I can see there is a relay on both the neutral and live to the heater. The relays are controlled together and cannot ...
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85 views

Keep volts the same but increase the amps in a 60hz 120v AC circuit

I have a over the range microwave with a built in fan for exhausting range fumes below. Would like to add an inline fan to it in the attic that matches the speed of the fan in the microwave but I ...
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2answers
273 views

Type of switch for AC power cord?

I have a power supply that has only screw terminals for its AC mains input. Currently I'm using a power cord from a computer that I cut the female end off of and attached fork terminals to (live, ...
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2answers
132 views

Are IC sockets suitable for mains voltage?

I need to derive a low-voltage galvanically isolated 50 Hz signal from 230 V mains. I'll use an opto-isolator for this. I'd like to use IC sockets for all ICs in this personal one-off project. ...
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0answers
60 views

X-rated capacitors in parallel

I want to build a transformer-less power supply (capacitive) to drive few 0.5W power LEDs from mains supply (230V). The 1uf X-rated capacitors I have are not good enough to drive them to full ...
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1answer
48 views

What's the purpose of adding a parallel impedance to a relay circuit?

This is the relay section of a PIR Sensor I have taken apart.: L_FUSED is 240VAC, and the relay is intended to turn on a light bulb from "OUT" (standard edison screw), so it could be incandescent, ...
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4answers
141 views

How to control power to a water heater

My water heater element is rated at 3.6kW at 240V. To use solar power efficiently, I would like to use excess solar power (in a grid-tied arrangement) to heat our domestic hot water. Our electricity ...
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4answers
174 views

230 and 240 transformer leads

So I have a transformer that is like 230 || 30 V. One thing I don't get that on primary side it has the following leads: 0 --- 230V --- 240V When it can be useful? I mean I can't think of situation ...
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2answers
302 views

Connecting LEDs to 220v without using a power supply

I'm designing a backlit custom picture frame, and I want to include the power supply (or the lack of one) inside the body of the frame. The problem is, since the frame design is more or less thin, I ...
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320 views

how to protect a 12 volt operating DC LED Bulb from 230 volts mains supply

I have made a DC Led BULB (7 watt) which is working on 12 volts input. By the way its input voltage range is 12-48 volts DC (using BP 1601 regulator ic) Now problem is that when i gave some bulbs to ...
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1answer
93 views

Building a wall-wart style case

I'm working on a project that will plug directly into the wall outlet, similar to a night-light or a wall-wart power supply. Internally, I'll use a AC-DC converter like this one. It has built-in ...
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47 views

Voltage at some point on a transmission line (a power distribution line in this case)

I am interested in knowing the instantaneous DC voltage (ball park) at a capacitor bank on a power distribution line at the instant I interrupt the circuit some distance away. If I interrupt the ...
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2answers
111 views

Using DPST Relay to control AC Load

Below is the functional schematic that I am planning to use to control an AC load (air conditioner in this example with max current draw of 32A). Since I am still relatively new to mains power and ...
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1answer
51 views

Mains into a relay?

Will hot/live go into NO and neutral into COM, to switch over 200v? Can someone explain please. I saw in some places it says natural into NO but what into com?
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0answers
111 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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1answer
109 views

High voltage distribution line fault current

On a conventional 7,200 volt distribution line, what would be the average fault current in a scenario like the one shown in the video below? Video Specifically, I'm wondering what the power ...
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2answers
85 views

Electrical measurements of Chicago substation from where can I get it? [closed]

I am doing a project on electrical load prediction using machine learning. Machine learning involves creating models based on past data. For creating these models where can I get data regarding ...
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2answers
180 views

Does unplugging a television from the wall socket make it safer? [closed]

Does unplugging a television from the wall socket make the electronic safer (against power surge for example) compared to: Plugged in, button on wall socket is off Plugged in, button on wall socket ...
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1answer
127 views

Strategies for powering an ATtiny micro controller and 40W peltier from mains

I'm trying to power an ATtiny1634 at 5VDC and a 50W peltier element at 12VDC. The microcontroller will, amongst other things, turn on the peltier via a 5VDC non-latching relay. I want to use an ...
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2answers
82 views

Limiting mains current

What would be the best way to limit mains (240V @ 50Hz) current? I want at least 1A of current. The output should be AC 240V at any frequency greater than or equal to 50Hz. It should be able to endure ...
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192 views

Energy harvesting from AC wire

I'm designing a home automation module and finding a way to supply power. Is it possible to harvest energy from existing AC wire using step-up current transformer? Also I can only find step-down ...
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3answers
362 views

What causes old power supplies to start humming?

I have a number of mains-powered devices that have begun humming (I assume at 50Hz, though I haven't measured it). These include clock radios, a speaker system, a lamp (20W halogen with a transformer ...
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117 views

Solar inverter with mains backup [closed]

I'm looking for a way to partially power an applicance (a fridge freezer for argument's sake) using solar/renewable energy. I don't expect the couple of hundred watts of solar power to be sufficient ...