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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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
113 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 ...
4
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2answers
229 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) ...
0
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4answers
115 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
61 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 ...
1
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1answer
65 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 ...
1
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1answer
63 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). ...
0
votes
1answer
46 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 ...
0
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3answers
113 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
69 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 ...
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2answers
73 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 ...
4
votes
2answers
168 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
255 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
71 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
84 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 ...
1
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2answers
119 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 ...
3
votes
2answers
93 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
113 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
votes
2answers
92 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
62 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
256 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
55 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
154 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
102 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
102 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 ...
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1answer
98 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
vote
1answer
37 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 ...
0
votes
1answer
67 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
votes
2answers
432 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 ...
1
vote
1answer
202 views

Socket wiring to relay + Ardunio / Pi

I’m working on a personal project at the moment and needed a small amount of electronics help. What I am building is a RaspberryPi/Arduino connected to wall plugs (which is not being fitted to the ...
0
votes
1answer
35 views

Finding out power requirements for plug replacement

I bought a inverter for arc welding that is imported and comes with a CEE 7/7 plug (I guess it goes to the European market). In Brazil we have two types of plugs one for 10A and another for 20A (they ...
5
votes
2answers
142 views

mains frequency accuracy worldwide

I like to build a device that needs long term time stability. In germany, one of the best simple clocks use the mains power frequency to obtain a time measure. While the frequency is allowed to change ...
0
votes
1answer
255 views

When to use AC line filter

Since I work with equipment where sensitivity to AC is an issue, I tend to build linear regulated power supplies for my projects. What factors do I have to consider, to decide whether I need a line ...
0
votes
1answer
96 views

Turn off power strip when another circuit is turned off

I have a switch in my wall which turns a outlet on and off, however I'm nearing maximum capacity on that circuit. I want to be able to plug more stuff into it so that I can turn it off with this same ...
12
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2answers
827 views

Is it OK to solder a power cord?

A few people have advised me to never solder a power cord directly to a PCB, but they couldn't explain why not. Why can/can't I solder it directly?
0
votes
1answer
141 views

Shorting neutral and earthing trips MCB [closed]

I live in India (220-250V, 50Hz). I have a single phase supply coming into my home. The main MCB trips as expected whenever the Live and Earth conductors get shorted. But I observed that my house's ...
2
votes
3answers
365 views

Power LED bed lamp from mains

I'm attempting to build an LED bed lamp that will be powered by 240V mains. The LEDs are these ones which if I use with a 12V supply and have calculated correctly will draw 0.24W each. I plan to use 5 ...
1
vote
2answers
209 views

1kHz AC from mains power

I've got a plan for a large electroluminescent display. EL panels are typically driven with a sine wave at around 1kHz, and I want to use mains power for this. What's the best way to convert mains ...
8
votes
1answer
211 views

To what extent to I need to be concerned about PCB punch-through when dealing with AC mains?

I'm working on a project that deals with AC mains directly. I know about maintaining proper creepage distances for adjacent tracks, and that you can add isolation slots if you lack the space to ...
2
votes
2answers
1k views

LED as 230V AC indicator

Answers to other questions here (e.g. 1) show capacitors used to drop AC voltages to levels suitable for a LED. I've seen much simpler circuits such as the one below simulate this circuit ...
19
votes
2answers
1k views

Is the neutral wire considered safe?

If the neutral wire carries current, why do many people believe that it's safe? I've heard "You can touch the neutral wire/bar in the breaker box and not get shocked. Only the hot can hurt you." If ...
2
votes
1answer
335 views

Shutdown controller for Raspberry Pi (+ other components) on mains AC

Inspired by the Shutdown Controller for Raspberry Pi in a car I would like to know if it is possible to build a similar circuit working with ~230V AC instead of 12V DC. I have a power adaptor where I ...
0
votes
3answers
355 views

Bridge rectifier destroyed at power up

I have this circuit built and it keeps blowing up my bridge rectifier when I power it. Is it because I have connected the chassis/system ground to earth ground? I cannot figure out what is happening ...
2
votes
0answers
81 views

Ground coupling a high voltage source with the A_GND and D_GND

I have a device that measures the current in the mains through a 0.01 Ohm 20W shunt resistor. The voltage across the shunt is amplified by a op amp and feed into a uC's ADC for farther calculations. ...
2
votes
2answers
90 views

What exactly constitutes poor mains voltage?

I've been wondering exactly what is meant by a poor quality mains voltage, specifically in places like Africa, where the mains voltage is considered worse than say the UK. Having done some research, ...
2
votes
1answer
117 views

Inducing Hum Deliberately in Analog Circuits

I would like to make a simple testing device that deliberately emits electromagnetic / electrostatic noise to test analog audio circuits for resistance to hum from switching power supplies, PWM ...
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3answers
2k views

difference between single double and three phase

If single phase is 230 V and 3 phase is 440 v then what about for 2 phase? And why is it so?
4
votes
2answers
241 views

How do I 'scope a mains appliance?

I am trying to study the operation of a single plate Induction Hob. I wanted to use an oscilloscope to measure some of the low voltage digital signals on the microcontroller inside. So I attached ...
0
votes
2answers
127 views

Turn a mains AC load off when another one is ON

What would be a way to turn OFF load A (10 amps) as soon as load B (10 amps as well) is turned ON, faster than the time it takes for a circuit breaker to trip (~15 ms)? Something like a voltage ...
0
votes
2answers
128 views

Non-isolated mains circuit and Ethernet

I'd like to measure voltage and current for a mains circuit using a microcontroller, and connect this to ethernet. Since I want to have 8 independent outputs, using an isolation transformer to measure ...