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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50 views

What voltage should power requirements be listed as?

I am listing the power requirements for a culmination of multiple devices for the US and the EU. For 120 volt mains, it appears most list the requirements (amperage) relative to 115 volt. Should I do ...
3
votes
4answers
95 views

Why aren't there any 3-phase domestic power-outlets, or any interest in 3-phase for household (mains) power or anything relatively low-power?

Since I discovered what 3-phase electrical power is on Wikipedia, I have noticed that it's associated with very high-power applications. I have not been able to find anything on the subject of 3-...
0
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1answer
31 views

simple switch for mains power

i dont know much about electronics.. ive got a set of active speakers set up, but currently have no way to switch them on/off easily without going around to each one and flicking the switch.. so i ...
4
votes
3answers
556 views

How can I safely use an aluminium enclosure without an earthed socket

For a mains-supplied circuit I want to use an aluminium case, so the case can act as a heat sink. However, I want it to be safe, also when there's no earth connection in the socket where the circuit ...
2
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0answers
22 views

How to pick a Balun and transformer for this power line measurement circuit

I was reading this paper here about measuring power line impedance using a network analyzer. It has a little circuit that they used but of course they're not nice enough to include a BOM :) How ...
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1answer
38 views

Convert 220V AC to give out TWO 12V DC 3 amps [closed]

I need an output of two 12 v dc 3amps , how can do it with a single transformer ? Well i am sorry for i framed the question badly! I have an appliance that need needs 12v 2amp for one component (...
6
votes
3answers
248 views

Add ground earth to a Chinese music player [closed]

I have this Chinese Portable Rechargeable Mp3 player. It has a two pin plug connector behind that is used to recharge it and some generic rechargeable non removable battery inside it. It has the ...
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2answers
53 views

Designing of an audio amplifier using LM386 and a preamplifier

This is the circuit . But i am still getting acoustic howling. What can I do to prevent it dynamically. Also I want to increase the sensitivity to the extent that when I rub my fingers in front of the ...
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2answers
261 views

Multimeter reading 0 and drawing too much from DC power supply

So I've got a circuit that requires both 5V and 3.3V so I bought a 5V 2A AC/DC converter from a store, which I will add resistors to later for the 3.3V. Before I connect it to my circuit, I wanted to ...
2
votes
1answer
96 views

What does neutral and live both being at +120VRMS above earth imply?

I am trying to fix a twenty-year old unsupported piece of scientific equipment that is very expensive, delicate, and needed by my boss/the lab in two weeks' time. I have identified that the reason it ...
5
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3answers
523 views

CE-compliant Schuko mains power switch: do I need to switch both poles?

I am currently revising a plug-in power meter (i.e. a power meter that you plug into mains, then plug the DUT into it) for CE compliance. It features power switching using a latching relay, only on ...
2
votes
2answers
59 views

When can I use the formula P=V^2/R?

I'm currently learning about the transportation of electrical energy through power lines. I now know that transporting current at a very high voltage cause minimal power loss compared to transporting ...
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1answer
39 views

Interfacing a mains referenced AC measurement circuit with a PC

I need to connect an AC mains referenced measurement circuit with a notebook and I wanted to know if its safe to do that without an isolator. The measurement circuit primarily steps down AC voltage ...
0
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4answers
145 views

240 V instead of 230 V on a true RMS multimeter

I'm a beginner in electronics, and I've recently got myself a UNI-T UT61E multimeter, which is marked as true RMS. I stuck its probes into a mains socket and I was expecting 230 V (Europe/Poland) but ...
1
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1answer
63 views

ESP8266 line voltage detection, schmitt trigger needed?

I want to read 230V/50Hz line voltage input signals with an ESP8266. Please have a look at my schematic, I chose an opto-isolator with AC input (LTV-354T) and added a simple RC filter to keep the ...
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votes
3answers
107 views

How to detect 220 VAC voltage using an opto-isolator

I created the following circuit. i plugged it in and it works!! Now i thought to add an opto-isolator to the circuit in place of the LED. The value of C was the same. $$ X_c = {(({220volts-1....
2
votes
1answer
64 views

How to stop leakage of mains adaptor [closed]

For the past year or so I have been using a mains to 5VDC adaptor to charge various devices. Everything is working perfectly fine but this charger I think, has a noticable leak to the low voltage side ...
0
votes
1answer
68 views

Remove mains hum out of amplifier

I have a headphone amplifier that is afflicted by mains hum 50 Hz and upper harmonics, below is an FFT of the spectrum with nothing connected to its inputs. In headphones you can clearly hear a buzz-...
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0answers
24 views

LNK306 based +/- 3.3V AC-DC power supply does not work right

I've been trying to design a power supply using PI's LNK306 using the datasheet and this application note. On page 10, the app note lists how you can create a +/- rail for the power supply. The note ...
4
votes
4answers
162 views

How do power stations maintain 50 hertz?

In the UK our mains standard is 230v AC at 50 hertz. So I understand that the generators at the power stations need to spin at exactly 3000rpm. This is true no matter what source is (nuclear, coal, ...
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1answer
58 views

Use voltage multiplier on mains?

If you wanted to double ac voltage, you could use one of those capacitor diode voltage multipliers. The thing I'm wondering is can you use it on mains? I've only seen people use them with transformers....
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2answers
58 views

Doorbell to buzzer with relay and AC to AC transformer

I have the following buzzer and want to use it with a switch by the door. Would the following configuration let this work or are there crucial parts missing? simulate this circuit – ...
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1answer
47 views

Battery charger disconnection

In modern devices (mobile phones, tablets, laptops) the battery charging current is automatically switched off when the battery reaches 100 %. After being disconnected, the power supply cools down. It ...
0
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0answers
44 views

tingly feeling when moving finger [duplicate]

while charging my Ipod or other USB based devices from a wall wart, i get a weird feeling, only when i move my finger against the metal surface. for example, the metal back panel of the ipod. Am sure ...
3
votes
4answers
239 views

How does ground mains work?

When I studied how AC mains power works, I learned that one of the wires is connected to the ground or a body of water so that it can get back to the power station. The concept baffles me. Every ...
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0answers
85 views

How to drive a MOSFET from AC wih max efficiency?

Short version: if I needed to drive a MOSFET from mains AC, that will be switching (PWMing) mains AC as well, and needed to do this "fast and often"* how should I derive the power to drive it's gate ...
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2answers
57 views

How to design an induction cooktop [closed]

I'm trying to create my own simplified induction cooktop. If I'd like to use 120V Mains, what determines the current draw of the coil used (is it simply the resistance of the coil)? Also, I understand ...
3
votes
1answer
42 views

AC power measurement query

I'm trying to understand and tweak this smartplug reference design from TI. I'm stumped on the Metrology Analog Filters section on page 1. What I do not understand is why is there a 0R resistor on the ...
3
votes
2answers
150 views

How do I hack my soldering iron?

I bought another soldering iron, very expensive to me. I am very exciting about it. Upon receiving it, My heart is broken. First, I saw the label, 220V; Our AC voltage is 110V. Tried it, doesn't work. ...
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2answers
141 views

AC/DC optocoupler wiring

Looking for some clarification on the proper wiring of an AC/DC optocoupler (HCPL3700, datasheet) when working with 120vac. From what i read online it looks like a need a resistor on the hot side ...
4
votes
2answers
702 views

Single LED powered directly from AC mains

Today I disassembled a power strip (power extension) and found a LED connected directly to AC with a normal resistor (not a power resistor). How is it working as I thought it would be burned in no ...
0
votes
3answers
47 views

Using thermal overload protection in AC-DC PWM motor driver circut

i'm having some difficulties with calculating the value of the thermal overload fuse in this circuit. The thermal fuse is used to protect the motor and the circuit behind it. The deal problem is that ...
1
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2answers
165 views

TRIAC Angle of Firing vs Power Delivered to Load, how calculate?

I'm building a phase control system for simple power control to a given load (heater for example). I need an equation to find the relationship between angle of TRIAC firing vs power delivered to load ...
12
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5answers
1k views

Anything special to consider when running a 12v “Bus” throughout my house?

I've recently begun playing a lot with tiny programmable computers/controllers (like the Raspberry Pi and the Arduino), and I'm planning to distribute several throughout my house as various sensors. ...
0
votes
2answers
140 views

How safe is my soldering iron? [closed]

I'm have a low cost (<2$) soldering iron, similar to the one shown in the image, except that it has 3 plug terminals. Suddenly something got me thinking about safety, out of curiosity I cut the ...
1
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2answers
37 views

Power Transformer with two Buchholz relays

In my workplace we have a power transformer, on its conservator tank there is a device like a Buchholz relay and its named as Atmo-Seal. What is the purpose of this device?
2
votes
1answer
117 views

What is a corner-grounded power system?

Another translation, another question. Original German: Antriebssysteme dürfen nicht direkt an TT-, IT- und an TN-S Netzen mit geerdetem Außenleiter betrieben werden! Rough translation: Drive ...
0
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1answer
55 views

Is it possible to make a 150 Hz resonant circuit from RF toroids?

I want to make an LC filter resonant at 150 Hz using a 2.5 uF 400 V CBB61 capacitor and inductor. They are shown in the image below. The toroid core looks like an RF toroid core but I don't know the ...
0
votes
1answer
48 views

How do I choose a cable /cord, connected to mains part, that is compliant with IEC 60601-1 3rd ed.?

IEC 60601-1 is a standard for medical devices. It describes which are the requirements for the Means of Operator Protection and Means of Patient Protection, the current leakages and so on. I don't ...
0
votes
1answer
58 views

Is it possible for lightning strike to travel up ground / earth pin on a mains outlet?

I live in a country that follows the UK mains specification, where there are 3 pins on a wall outlet with the topmost pin being earth/ground. Now, is it possible that during a lightning strike, extra ...
0
votes
1answer
73 views

How to wire the mains to a transformer for end user safety?

Because this can be deadly, and is best left to someone qualified; advice for hobbyist projects on the web are reluctant to offer advice on safely handling mains connections. The get-around is to ...
0
votes
0answers
31 views

Why are Watt-hours used instead of Joules? [duplicate]

Does anyone know why Watt-hours are used instead of Joules in the power industry? Considering that 1Wh=3600J (since 1W=1J/s and there are 3600s in an hour), I don't see why a nonstandard unit would be ...
1
vote
1answer
613 views

I bought an air conditioner in Thailand rated 220v-240v, 50 Hz. What could happen if I use it in our country which uses 220v, 60 Hz? [closed]

I bought an air conditioner (split type) rated 220v-240v, 50 Hz. What could happen if I use it in our country which uses 220v, 60 Hz? A lead technician from a refrigerator and air conditioner shop ...
8
votes
1answer
173 views

What is this high power switch symbol?

I am a medical physicist, and I program software for MRI scanners as well as develop electronic devices that interact with them. Because of the way MRI works, it is necessary to use very large power ...
1
vote
0answers
52 views

How were the voltages/frequencies of mains defined? [duplicate]

In other words, are there any historical reasons that set mains supply voltage to 120, 127, 220, 240Vrms per phase, and 50/60Hz? These are the most common voltages/frequencies, there are many others, ...
0
votes
2answers
77 views

How do I calculate the impedance needed to drop 120V AC?

I've been wanting to use the H11AA1 zero-crossing detector to detect the zero-crossing points of Mains Voltage - 120 V AC @ 50 Hz. The data sheet says that the max forward currents of the diodes are \$...
2
votes
1answer
276 views

Triac spurious triggering issue

I have a circuit where I am using triacs to switch home appliances like fan, tube light etc. This is the circuit I am using: (TRIAC1, TRIAC2, TRIAC3 come from arduino GPIO pins) First load is a ...
2
votes
1answer
90 views

Spurious triggering in TRIAC due to EFT

I am working on a project to control AC load using TRIAC In normal operation it working complete fine But when a fan regulator specifically step type capacitor regulator is used in vicinty the ...
4
votes
2answers
153 views

Why do offline switching converters often use discrete rectifiers for bridge?

In conjunction with my independent study of switching converters using textbooks, I am more or less obsessively tearing apart all the low-ish power (say 5 - 25 Watt) switching converters I can find. I'...
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2answers
190 views

Cable rating - What is the max amp for a 1.5-1.75mm cable?

I have a new hob (magnetic induction plate). It requires 7200W/32A. The power grid's voltage is 230V (Europe). I have already installed a thick cable and I want to use it (it would be difficult to ...