Mains electricity, typically a higher voltage AC waveform used to deliver electrical power to households. In North America 120 V, 60Hz, in Europe 220, 50 Hz. What most people will plug appliances into.

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How does a “break” in the neutral wire enable it to reach the full line voltage?

The answer to Is the neutral wire considered safe? states: When everything is working correctly, it should be at most a few volts from ground. However, and this is the big gotcha, if there is a ...
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2answers
53 views

Is it possible for mains power to drop during peak times?

Disclaimer: I'm not after repair information or modifying any appliances myself. I'm after a reason why this is happening. I have noticed that during peak times (6pm - 10pm) that power to mains ...
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1answer
85 views

Why does a mains appliance give a shock after it is completely unplugged

My wife has a food processor, bought a few weeks ago, powered directly from the A.C. mains, i.e. not via a "wall wart" power supply, and, after it has been switched off at the wall and fully ...
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0answers
39 views

Determine a transformer's windings

I'm trying to find out what the pinout of a transformer is. I found the following diagram in a service manual of a device similar to what i salvaged this transformer from: Now. To test this, I'm ...
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1answer
55 views

I want to adapt a VFD

If I feed single phase electricity into a 3 phase input VFD, I know it needs to be derated on the output by about 50%, but how does it cope with the difference in voltage, as rectified 230v rms gives ...
1
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1answer
121 views

Where does 264Vac come from?

Power supplies often accept an input range of 90-264Vac. I am wondering where the 264 comes from. A couple of random examples from power supplies available: 85 - 264 Vac input range (100 - 240 Vac ...
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4answers
348 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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1answer
86 views

Is a 115V rated transformer expected to accept US mains voltage (120V)?

< question completely reworded since people thought I was looking for appliance repair instructions > Many "Power Transformers" are rated at 115V or 230V. It seems to be the most popular rating. ...
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3answers
175 views

How to build very low cost current transformer?

Im building low cost home energy monitoring system. I want to see how much energy is used by water heater, big water pump, kitchen equipment, lightning, computer. I would be awesome if I could measure ...
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0answers
7 views

Arduino UNO rev 3 toggling 230v submersible pump on intervals [migrated]

I am software programmer and hobby farmer. While i was working on a hydroponic farming stuff, i had to use submersible pumps with timers. i dont want to buy timers that are actually tedious scheduling ...
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3answers
377 views

Transmission lines in USA, household transformers - efficiency and economy

I want to ask about efficiency and economy of electric power distribution in USA. I live in Europe and American standards are so weird for me. I was very surprised when I saw this: See inside main ...
4
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1answer
375 views

How can I safely prototype a mains power circuit?

I'm building a device that has a mains power component, which I need to prototype before building to make sure everything works. I know I need to make sure wiring—and insulation!—is thick enough to ...
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0answers
44 views

How to add a desirable phase shift in the input from 3-phase ac mains?

I want to build a 12 pulse rectifier circuit. I know delta-wye or wye-delta transformers can be used to add phase shifts equal to the multiples of 30, but I don't want to use transformers. Is there ...
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2answers
94 views

How can I make a 5mm LED rope using 6v transformer [closed]

I want to glow LED using a 6v AC transformer. I want to add 18 color changing leds (5mm) as series. I cant add too many wires through the rope (pipe). See my plan: what are the components I ...
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1answer
94 views

How can I make a LED rope using mains (AC power) [closed]

I want to glow LED using AC power. How can I add combine multiple LEDs to make an LED rope? Versions that I would like to build are: 18 x 5mm LEDs 20 x 10mm LEDs Mains voltage here is 220 V AC ...
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1answer
98 views

How can I make AC powered 5mm LED string? (with more than 16 LEDs) [closed]

I want to make an AC powered 5mm LED string. I searched a lot but I never found a working one. I just tried one experiment from the Instructables site. But when I connected it to AC power, one ...
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2answers
85 views

3-way dimmer switch schematic

I am building an AC dimmer circuit to control from an Arduino using this schematic: I need to make this dimmer so that it can be used as a three way switch as well. How would I modify this circuit ...
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2answers
201 views

Is a 250V lamp compatible with both 120VAC and 220VAC?

Is a 250V and 660W lamp compatible with both: 120VAC at 60Hz, and 220VAC at 50Hz? And why? Also, does the frequency of the mains have any bearing on the lamp? In North America I was very ...
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2answers
79 views

Replacing a battery pack with a mismatched DC source

I have a PCB which is nominally powered by a custom battery pack. Specifically, this battery pack: So five cells connected in series, at 3.6V each, which I assume means that the nominal output ...
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1answer
49 views

Would this be ok to control the speed of a PC fan? [closed]

I have a 240mm PC fan connected to a 12v adapter. The fan is quite noisy and i would like to have the option to turn the speed up/down or off completely. The Fan is: Current (A): 0.18 The 12v Mains ...
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1answer
51 views

Current clamp mains appliance [closed]

I want to measure the current to a device using a current camp. I have a mains extension cable I plug the device in and I strip the mains extension cable to reveal the live, neutral and ground wires. ...
10
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4answers
1k views

Where is the ground/negative for overhead power lines?

I recently learnt that ground can be used to complete circuits using high voltages. I'd like to know if this is how overhead powerlines work, and if so where exactly do the cables/circuit terminate - ...
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1answer
152 views

Small AC Transformer

Came across these small Zwave controllers here .These are small enough to fit inside the electrical switch housing in the wall. Just wondering how is this device so small as the AC->DC transformer is ...
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2answers
295 views

It is it possible to safely use a 110V variac (variable transformer) at 230V?

I've come across a variable transformer/variac which is designed to be used with 110V input. Our line supply here is 230V. If I was careful not to exceed the VA rating of the transformer (920VA) ...
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4answers
224 views

Surface mount transformerless 230v to 3.3v on a small board

I am trying to design a 3.3V mains power supply to go on a PCB approximately 50x25mm in size (this will include other functions too!). I've come across the Supertex SR086, which is almost perfect, ...
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2answers
92 views

How to connect 120V to a relay on a prototype board?

I'm designing a microcontroller controlled switch. I idea is to have a 120V outlet controlled by time of day, or a motion sensor, etc. The plan is to have a lamp plugged into the outlet. I will ...
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1answer
95 views

How do external circuits in light switching units (such as Lightwave RF) use the mains wiring for power?

LightwaveRF is a simple switching unit that contains additional circuitry to enable automatic wireless switching. The additional circuit is powered by the mains light switching circuit. This is my ...
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1answer
77 views

Safety considerations designing a mains powered device

I am building a device for hobby purposes- a 3D printer specifically. It already uses mains (240V AC) powered heater elements to heat the build chamber (4 ceramic cartridge elements at 100W each). ...
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1answer
51 views

AC Transformer Power Cable

I have recently purchases an 120 Vac to 12 Vac transformer similar in design to the one shown here. I am curious as to the best way to wire this up. I am not a big fan of making a suicide cable for ...
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3answers
130 views

High frequency mains sensing

I want to sense mains voltage at a frequency faster than 5000Hz, with a microcontroller. The idea behind this is to visualize the actual shape of the AC voltage, and eventually to compare it with the ...
0
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1answer
75 views

Strange voltages in my office space [closed]

On wanting to put on lamps I measured the conductors coming out of the ceiling - and they seemed a little off to me, so I wondered if anyone could tell me what it means. I'm in Germany, and the ...
1
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2answers
113 views

Fault-current circuit breaker breaking on grounding neutral conductor?

I just put some lamps on and got the fault-current circuit breaker triggered. While skinning the earth conductor the knife touched the neutral. I was a bit puzzled: I thought that happens only under ...
5
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4answers
316 views

Using oscilloscope safely with AC mains

I know there is quite few discussions already on this topic, but since english isn't my first language I though it better to get some more information about this. I have used oscilloscopes to ...
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1answer
561 views

50/60Hz inverter output inductor design

Given a SMPS PWM inverter (for example an UPS) supplying voltage/current at 50/60Hz, how do you design an output inductor? I don't mean how you compute its value in uH/mH nor its current rating in A. ...
0
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1answer
88 views

Is there any benefit of making lamps with high wattage LEDs but low wattage driver circuits other than cost?

Over the past few years I have bought a number of GU10 mains voltage LED bulbs and have generally been disappointed with their brightness. The 9W LED bulbs I bought (supposedly 460-590 Lumen) produce ...
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0answers
106 views

How to isolate DS2406 switch from mains? [closed]

I would like to use a DS2406 1-wire control chip to switch a mains load. Isolation is required and I would like to use the 1-wire supply. There are no power supply at the remote end, only 1-wire ...
2
votes
2answers
173 views

COM port goes down unexpectedly, but Arduino Leonardo keeps running

I am observing strange behavior with my Leonardo board. I use 9V AC/DC adapter to power it. Relay extension board is attached to digital pins, and relays are used to control several valves and ...
2
votes
2answers
106 views

Symmetric power sockets – design considerations in electrical devices

There are various single-phase power socket standards in use. Some countries use plugs that can be plugged in the socket only in a specific orientation (for example, the United Kingdom) while other ...
4
votes
2answers
138 views

Consistency of the mains frequency throughout the UK

I'm working with a number of frequency meters which are reading the mains frequency in the UK from different locations. The problem is that I haven't been able to find information on whether there are ...
0
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2answers
102 views

How many USB cables does it take to charge a mobile? [closed]

Loads of devices these days have USB links to enable you to link them to the PC - eBooks, MP3 players, tablets and so on. To save cable the same USB cable also has a link to a plug that goes straight ...
0
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2answers
82 views

Variac power on current surge

I am looking into buying a variac from Ebay, but many of the devices on sale are rated for 2 - 3kVA (@220VAC). Now my concern with these devices is that simply turning them on (with or without load) ...
2
votes
1answer
374 views

Arduino Hangs when Connected to 220V Supply [closed]

Product Used - 12V 4 in 1 Relay Board (got it from eBay), Arduino Duemilanove, Ethernet Shield. AIM - Control my Room Lights with Arduino. (Home Automation) My Connection - Arduino is connected to ...
-1
votes
1answer
57 views

Can I use a UPS to compensate for unsteady line-power? [closed]

One of the outlets in my home provides unsteady power that causes connected electronics to occasionally shut down. If I buy a battery backup device such as this will it be able to compensate for ...
5
votes
1answer
193 views

Power line voltage out of phase with ambient 60Hz electrical noise - why?

I just bought my first oscilloscope and have been tinkering with the measurement of different signals just to learn the ropes and familiarize myself with the scope. One of the first things I noticed ...
1
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1answer
119 views

Inline Mains Switch with microcontroller

I'm looking for some inspirations/references as to how I might go about designing a switch powered by a microcontroller, switching a mains powered device . My ultimate objective is to create a zigbee ...
1
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1answer
125 views

50 Hz antena for monitoring mains frequency fluctuations

I would like to follow fluctuations of the mains frequency (50 Hz, yes, I know they are very low) in the lab without connection to the wall socket. I suppose it should be kind of antenna (capacitive ...
1
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1answer
104 views

Will the relay break if the disconnected end voltage is too high

I'm trying to create a simple overvoltage protection circuit. In brief, there are times when my mains voltage goes well over 250V (normally 220) and I want to switch off the whole thing connected to ...
1
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1answer
41 views

Regular power failures - RCD tripped

Day after day, between 13:30 and 14:30, most frequently a few minutes after 14:00 we're getting power outages in our firm. One (random) or both of RCDs protecting circuits to whole wing of the ...
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1answer
73 views

How can power line devices be affected by a power supply?

I have two power line adapters plugged into mains and I've noticed that whether a cheap power supply is plugged in, the data transfer rate drops dramatically or even drops to zero. What's the theory ...
0
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2answers
514 views

Arduino UK Mains Light Switch 230v to 5v

My aim is to create a wall light switch similar to the LightwaveRF ones with a momentary switch rather than a rocker style switch. To handle the momentary switch I will create a custom chip based on ...