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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246 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 ...
-1
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0answers
34 views

How can a storm damage selected items? [on hold]

We had some storms here in Dallas on Monday. I did not lose power and it did not seem to be a severe electrical like we get in the spring. But, my WAN gateway (cable) appears to have its ethernet ...
-1
votes
1answer
29 views

Controlling lights powered via mains using an 8 channel relay module [on hold]

I've come up with this schematic and I'm just wondering if this is correct. I'm using raspberry Pi GPIO pins to blink 240V 40W light bulbs using a relay module. Ignore mains for the Pi for now I ...
2
votes
1answer
95 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
votes
3answers
510 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
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2answers
58 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
38 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 ...
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4answers
142 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 ...
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1answer
54 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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3answers
96 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
63 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
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0answers
41 views

Remove mains hum out of amplifier

I have a headphone amplifier that is afflicted by mains hum 60 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
19 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
152 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
55 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
51 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 ...
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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
228 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
75 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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votes
2answers
55 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
41 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
142 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
121 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
689 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 ...
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3answers
36 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 ...
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2answers
131 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
130 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 ...
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2answers
36 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
110 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
51 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
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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 ...
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1answer
55 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 ...
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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 ...
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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
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1answer
609 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
152 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
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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
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2answers
75 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
255 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
87 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
151 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
162 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 ...
2
votes
3answers
68 views

Sensing state of an electrical appliance [closed]

I know nothing about electrical engineering however... Is there a way I can detect when an electrical appliance is on? For example when I turn on my tv, a small blue light turns on so I know, but say ...
2
votes
3answers
454 views

Where are these 50Hz noises from?

Circuit structure: An AC to DC power converter MeanWell 220V to 5V. The output is 5V. The power grid runs at 50Hz. We build DC-DC converters(Power Module) with multiple orders of Low pass filters ...
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1answer
81 views

What is “mains outlet tester” (for proper wiring) in the context of US power connector standard?

I'm curious about this comment. It says what ... in the US or UK you should be able to go to a hardware store and buy an outlet tester for very little money. This is a little plastic housing ...
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4answers
140 views

Benchtop circuit breaker

I repair electric appliances and tools. Every once in a while, the main circuit breaker trips when I plug in a device. I don't want to prevent a circuit breaker from doing its job, but I would prefer ...
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3answers
137 views

Should I continue with daisy chaining?

I've been daisy chaining power strips and it was no issue until my friend told me it's dangerous. I was using 2 monitors, fan, desktop,55inch TV, monitor speakers, and a phone charger. And he told me ...
6
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8answers
1k views

Can I use a 10A light switch with an appliance with a 13A fuse?

I have a vacuum cleaner, which I wish to add a switch to, so that I can leave it plugged in all the time and use the switch to turn it on and off. The vacuum cleaner has a fuse rated 13 Amps. I ...