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Questions tagged [mains]

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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111 views

Switch between 2 power supply feeds without device losing power

I have done a search on here but didn't find the answer (maybe "woods for the trees") but here goes... A brief 'background' -- In my house, there's a switch by my front door that turns on/off the ...
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Why is the line-to-ground voltage half of what it should be?

Our electric power provider delivers 240 V, 60 Hz split-phase power to residential buildings. I've been checking our three-prong receptacles and I normally get the following measurements: line-to-...
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Connecting a multi-PSU server on different lines with different earthing

I am currently preparing to set up a new server which has two PSUs (for supply redundancy). Of course it would be logical to connect them to different sources, but the situation I'm dealing with ...
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SMPS mains hum on guitar rig

My guitar rig consists of Guitar -> Audio Interface (Steinberg UR22) -> Laptop (via USB). I listen to the (processed) audio using headphones connected to the audio interface. ISSUE: When the ...
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191 views

Powering 10.8V DeWalt cordless drill from mains

There was a couple of questions on how to power a cordless drill, but they are all about power supplies. I've got a DeWalt 10.8V cordless drill and its battery connects through 4 pins instead of 2 or ...
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53 views

Checks for AC Mains Product Compliance

First of, I apologize if this type of question has been answered before (I did have a search). We are a small startup about to go through manufacturing stage of a product. I would like to ensure that ...
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43 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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59 views

How is AC load distributed across on-site generation and the utility?

I’m trying to understand the physics behind AC load distribution when distributed on-site generation is installed and the load is also connected to the grid. In the diagram below, I have a building ...
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1answer
149 views

Replace mains 12v power-supply with 12v battery

A Yamaha digital piano is powered by a mains power-supply. The power-supply states the following input/output values: INPUT 100-240V~50/60Hz 0.5A OUTPUT 12V === 1.5A (Where I have written === there ...
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51 views

Transformers and high voltage elements

I've been trying to learn how to properly set up a circuit for power regulation. Often I hear for domestic use that it is better to use a transformer to isolate the device as well as stepping down the ...
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4answers
185 views

How can I run my e-bike wheel on AC power?

I have an electric wheel designed for an electric bicycle conversion. By my understanding, the wheel is essentially a 48V, 1000w rated brushless DC motor. It comes with a thumb throttle and kill ...
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94 views

Linear power supply and mains filtering and protection

I'm designing my first linear power supply for my project which needs dual rail 12V (the regulation from 15V to 12V is on another board, 7812 and 7912). The +12V (+15V) rail will draw about 250mA, the ...
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338 views

Where exactly in the environment does the 60Hz power line noise be picked up from?

I am measuring EMG signals using ADS1299, and I have problems removing/eliminating the 60Hz noise in my measurements. I measured the EMG signal in differential mode, and I also incorporated a driven ...
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153 views

Swap main terminals of zero-crossing triac

The question I have is maybe silly, but I cannot find strictly related info. When designing a mains switch with an optotriac driven triac (or discrete SSR for you), during layout I swapped the ...
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284 views

Will this resonant IR2153 circuit work?

Will this work? Proposed principle of operation: R-C oscillator starts resonation of coil and capacitor. The R-C oscillator is overriden by the induced voltage. The frequency is dynamically adjusted....
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328 views

Protection of Energy Meter from 35KV spark

I have been building a prototype of an energy meter for a project. One of the aims of the project is to make sure the energy meter can withstand a 35KV Spark applied to it. I was wondering how this ...
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70 views

Mains Voltage Distortion Question

I am studying the effect of a diode rectifier on the mains. When I started to increase the inductance, the current had less distortion but the input voltage became more distorted. When I looked at the ...
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60 views

What is the correct way (read “correct way according to the law”) to choose the section of a power cable in the EU and UK?

I am wondering if there is a standard process across the EU in particular Germany, France and the UK, for choosing the the section of a power cable. Suppose that: the cable is to be installed in an ...
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130 views

Microcontroller reset on mains connection

I'm helping someone build a static VAR compensator. We figure it'll be evident that the power factor is being corrected if there's a display that shows AC voltage and current waveforms, so one can see ...
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96 views

Why not include data into a SMPS?

Something I have been thinking that could drastically reduce the cost of powerline devices in a bridge that uses the switching circuit to provide both regulation and data. Basically you could have a ...
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0answers
39 views

How to integrate NEMA x-15-P into mechanical/electrical design

What are some ways (or what is the typical way) that a wall mount device mechanically and electrically attaches the AC blades/plug into a design? I've worked with panel mount IEC320 and cabled power ...
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51 views

How do I create a visual and/or auditory indication that an inverter has switched off and the mains are back on?

EDIT I came to know that o/p of inverter is AC. I apologize if I sounded silly previously. To be more specific, How do I create a visual indication an audio indication in my living room such ...
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238 views

What controller for a 400W AC-DC SMPS?

I would like to build a big AC-DC SMPS. I built a little one based on ST's VIPer22A. This is a nice little IC that can give up to a couple watts (my design was 5V 1A). It was easy enough to design ...
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258 views

How can this isolated DC/DC converter claim a 3kv rating?

I'm referring to the Murata Power Solutions CME series DC/DC converters. Datasheet: http://www.murata-ps.com/data/power/ncl/kdc_cme.pdf If you look at the footprint of package (the -3C variant), ...
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174 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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32 views

Reason for failed MOSFET and Power Resistor

I am trying to repair the Power Supply for a Phillips TV (the power board is named DPS-130QP). I quite quickly found a burnt out resistor (R611). And after removing a heatsink on a nearby MOSFET (Q601)...
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87 views

Why use an inductor as a fuse?

I opened a small "wall-wart" power supply that had failed, and discovered the culprit to be a low-value (100µH) standard (axial, green) inductor. This inductor had a visible crack along it, as if it ...
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1answer
51 views

Fast mains outage detector

What is the fastest mains outage detector at <1ms? Anything that uses a 12V DC adapter or a mechanical relay is not an option for me because it has a long delay. Is there an AC driven static/solid ...
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48 views

Multiple home appliances emitting the same high pitched noise

About two weeks ago, I came home and noticed a piercing high-pitched noise in my room. After searching for the source of this noise, I found it was coming from my PC's power supply unit. Later that ...
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1answer
34 views

Power 3V EL wire inverter with DC adapter

For a project I have 20 pieces of EL wire that each have their own 3V (2xAA) inverter. Now I think it's a complete waste and hassle to replace the batteries every so many hours, so I wanted to try and ...
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32 views

Triac design for switching load to resistive heater

I'm designing a triac-based relay circuit to switch ac mains on-off to a resistive heater. The app note (AN-3004) for the opto isolator I am using, the MOC3061, suggests using a gate resistor value ...
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64 views

How can I Power a 20-50mA LED from the 240V AC Wires of a Motor in a Safe Way?

I own an ice cream machine which is perfect, except it lacks a light so one can check the state of the process. The motor case would be the perfect place to install a white LED, which will consume ...
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Inducing noise for testing AC line filters

From a previous post of mine, you can see that I am trying to test the efficacy of some AC line filters. I got it to connect properly this time without frying my load, but we cannot seem to replicate ...
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46 views

Reasons for filament LED bulb failure?

I recently purchased a filament LED bulb. However, when installed (AC 220V), it wasn't working well: it had a very low light. But sometimes (~ every 5min) it lights up for a few seconds at its normal ...
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128 views

Does a PC need pure sine wave? Need to test using 1000W, 120VAC 60HZ input, 240VAC 50HZ output

I need an OTS (Off The Shelf) solution to test PCs before they ship to Europe and beyond. I need to provide up to 1000W of 240vDC 50Hz power from a 120vAC 60Hz outlet, because I want to make sure the (...
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1answer
128 views

How to connect an AC line filter

I am trying to connect an AC line filter (rated for 115/250VAC) on the load side of a 24VAC transformer (part# BPD2G, datasheet here). The first filter model I used is Delta's 03DBAW5. From the ...
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34 views

To ground capacitance of a power line modelling

Is it correct to model to ground capacitance of an overhead power line as ideal current source when using matrix methods for load flow calculation?
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39 views

Measuring ac mains transient

How can I measure transients in AC mains? For example, after and before using a GDT or a MOV. The thing is, I don't have those expensive HV differential proves for the oscilloscope. And, if I use the ...
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188 views

Understanding flyback transformer datasheet

Please see the below image of a flyback transformer I found. I see voltage/current outputs at each secondary winding. My question however is, how are these determined? I thought the output levels are ...
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177 views

Measuring 0-240v 50-60hz Mains AC with Arduino/MCU

What is the proper way to measure 0-240v 50-60hz Mains AC with an arduino / 3.3v mcu? (Edited to include a diagram of a proof on concept, which is transformerless) Can anyone confirm that this is ...
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137 views

high voltage buck converter

I'm a second year EE student. I was trying to make some circuits by my self. I wanted to make a Buck-converter, from mains. I'm from India. Here mains are 220v to 230v 50Hz. My aim was to attain a ...
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64 views

Circuit for Neutral point of 3-Phase mains

I wonder if the 'Neutral Point' as mentioned in the attached image is correctly labeled or not? Is there any mistake in this 3-phase circuit design? Edit 1: Also it looks like the 'Neutral point' is ...
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Can I simply add a 240V Neutral to SONOFF TH10 when replacing wall thermostat

So, I have purchased a SONOFF TH10 wanting to use it to replace my wall mounted thermostat. The thermostat has 2 connections: Always-Live and Switched-Live (which is activated of course by the ...
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2answers
153 views

Transformer open secondary

In the circuit provided by the link, would having an open secondary coil (not having it connected to any ground) damage the it? The coil is connected to pulsed 240v ac at 50hz. If it is not arcing, (...
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39 views

Can I use a RF and/or Time-domain reflectometer to find 'wet contact'?

Friends of mine have a circuit where the RCD trips but only after prolonged rain. There are a number of garden and security lights on that circuit so I very much suspect there is a junction box where ...
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Electrical safety measures in LED bulbs for the European market

Which electric safety measures are required to introduce LED bulbs on the European market? Which electric measures prevent that the plastic LED bulbs will melt down or ignite at the end of life? I ...
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Designing an inverter with its DC volt and gnd connectors as multi-pins along the PCB, how do i lay out my decoupling capacitors?

Should I distribute multiple decoupling capacitors along the connector rails? Or Should I have a few large capacitors centralised? Is there a mathematical way to evaluate this? Any other methods ...
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43 views

on a network analyzer's measurement what's the meaning of a negative PF?

on a 1 MVA transfomer, process in the place is plastics injection machinery. On the plotted data from an analyzer results in PF jumping from 0.998 to -0.997 (roughly) for all the measurement period ...
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38 views

Reference material for mains-interfacing circuit safety

I've designed a simple switch/timer circuit for the following environment: Residential installation for North America (technically only for Canada) Single-phase 120Vac Current of switched output ...
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1answer
84 views

Understanding this TRIAC circuit

I have an inquiry about the circuit below: When a high signal is continuously given to the transistor, it enables the optotriac with zero crossing. The optotriac enables the power triac, and the AC ...