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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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How to obtain 360vdc from 240vac for audio use without a transformer?

I'm in the process of creating a tube guitar amplifier with an output power of ~6w (fender vibrochamp AA764) which requires the use of 360-400vdc. How could I obtain such a voltage from mains without ...
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30 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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25 views

How can I test which mains wire belongs to neutral and which to ground? [migrated]

I currently live in Spain, in an old building, where apparently electrical codes don't strictly apply... because not all outlets have ground or, indeed, not all connections are grounded. To make ...
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24 views

Clearance distance and resin filler

I'm designing a circuit to detect presence of AC line voltage. It's actually a very simple device with AC side made up of a 200Kohm 1W resistor and an optocoupler and a protection diode. There will be ...
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2answers
56 views

Earth line safety [closed]

I am working with a conductive appliance that a user will be in constant contact with over extended periods of time and the appliance is constantly earthed. These two facts cannot change, other than ...
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1answer
90 views

Can we make the illumination on a bulb higher than the other when two are in series

I have a question: If suppose we have two identical bulbs connected in series with a supply source. Is there any way to illuminate one of the bulbs brighter than the other through any means, except an ...
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1answer
60 views

Is there a colour standard for mains 'signal' wiring?

Hello I am currently wiring a mains powered chassis. I have relays which use mains voltage levels for controlling other mains voltage relays. I would like to differentiate between the signals by using ...
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1answer
48 views

Neutral current

I have an old switchboard with a 16 mm2 mains cable and a 16mm2 neutral return. At a different date, someone has added another 16mm2 single main cable to the board. The two phases are feed from 2 &...
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102 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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1answer
79 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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1answer
46 views

Choosing inrush current limiting resistor for a mains rectifier

I am having a trouble with a mains rectifier. Simplified schematic: simulate this circuit – Schematic created using CircuitLab Only problem I have is that R1 sometime explodes during circuit ...
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3answers
186 views

Why is this camping light deadly?

I am learning, so go easy on me, if you can. In a video with BigClive, he takes apart a camping light and says it's deadly when you have mains plugged in and usb plugged in at the same time. In that ...
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27 views

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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3answers
87 views

How to verify if all 3 AC phases are in order? [closed]

We have 220V main lines where we currently live and we have a 3-Phase connection. We have an Air conditioning unit that requires 3 phase AC input with the correct phase sequence. If the phase ...
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1answer
1k views

Mains transformer blew up amplifier, incorrect description in wiring instructions?

I am assembling a power amplifier from a kit I purchased from Velleman (Module: VM100). With the amplifier I purchased this mains toroidal transformer - . The amplifier came with these instructions: ...
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1answer
56 views

Topology choice for wide-output-voltage-range SMPS

I'm intending on building a off line (230VAC), 50W, isolated, constant-current switch mode power supply. This by itself is not a big challenge with the plethora of application notes and examples ...
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3k views

What killed these X2 caps?

A few years ago, I designed an MCU-controlled dimmer driving a 150W mains halogen lamp. This is in Western Europe; 50Hz 230VAC. It uses X2-rated capacitors as capacitive droppers for the power supply, ...
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2answers
34 views

Use of the same transformer with a replacement offline SMPS controller?

We have an SMPS that was designed by a third party. The controller, VIPER100, has gone obsolete. ST don't do any sort of direct replacement, but other manufacturers do similar devices or at least ...
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1answer
127 views

AC mains rectifier issue

I built a simple full bridge rectifier with AC Mains input, but I noticed that: When the input is 220 V rms the DC output is only 293 V, but I expected the DC output voltage to be 220 x sqrt(2) = ...
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74 views

AC “chopping” power supply inrush current problem

I've made a simple AC to DC chopping/switching power supply circuit (I'm not sure if it's called that) as shown below. in the left part of circuit (which is the gating/chopping part) when the ...
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1answer
199 views

Fuse symbol on toroidal transformer

I was searching today for a new 24V transformer, and I found that some of them have a "fuse" symbol on their label, and I was wondering what this fuse symbol means? Does the fuse symbol on a ...
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1answer
52 views

How can I match phase voltage between a transformer primary and secondary?

I am trying to make a circuit to transform 240VAC, split-phase to a 0 to 5V waveform for an Arduino ADC so I can measure the mains voltage. I have read this question (How to measure line voltage (220V)...
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2answers
53 views

Isolating main power traces on backside of the PCB

I am currently making a build-in PSU for my own audio-effect-rack-thing. The internal PSU consists of two print-transformers(THT), one for 6VAC and the second one for 9VAC. These are also pretty low ...
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3k views

Why is there a voltage between the mains ground and my radiator?

I have an anti-static mat that comes with a plug that only has a ground lead. Out of curiosity, I measured the voltages between the live, neutral, ground, and my radiator. As expected, there is ...
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52 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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2answers
74 views

Standard Powered Female DC Connector

Is there a standardized female DC jack designed to provide power, much like AC female wall outlets? Typically devices that require a DC power input are powered by individual external power supplies (...
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1answer
69 views

zero-crossing detection: to optocouple or not to optocouple?

That is the question. Most of the diagrams I have seen on the interwebs are of the opto-coupling school of thought: But the AVR182: Zero Cross Detector application note just throws in the resistors ...
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3answers
103 views

Is UL approval only required for the power supply?

Suppose a mains powered device has a PSU in the assembly that has a detachable cable to the mains. Is it just the PSU that needs to be UL approved/compliant? Is the whole device therefore UL-compliant ...
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3answers
88 views

Convert kW generated per minute to kWh

I have the data of power generated by a solar panel per minute in kW. I need to calculate the total number of kWh generated per day. How do I do this? So far, I divided each value of kW by 60 and ...
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2answers
135 views

How to detect a partial discharge in a noisy signal?

I am working on a competition where we are required to detect partial discharges in given signals. Each signal represents a measurement of some power-line voltage. I know that partial discharges ...
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57 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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1answer
61 views

Detecting mains power change: One signal when on, another signal when off

I'm trying to connect a timer output wirelessly to another circuit. These are on two separate power lines (different phases, circuit, long distance), so I thought of connecting them wirelessly, I'll ...
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49 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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1answer
30 views

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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3answers
1k views

Can I use a 28 VDC 10 A relay to toggle a 10 kV DC 0.03 A source?

Neon signs use transformers that can output at 10 kV DC at 30 mA = 300 W. I want to toggle this power with a common 5 V relay, but the DC rating for these are about 28 V DC at 10 A = 280 W. Does the ...
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1answer
96 views

Is a safe 110/120VAC benchtop power tap possible?

I have a benchtop power supply that provides +3.3, +5, and +/-12VDC. I've started cannibalizing small appliances for parts, and I'd like to have similar power taps for 110/120VAC. Does such a thing ...
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2answers
73 views

Mains AC overvoltage protection using a TRIAC

I am trying to design a circuit that protects 127V appliances if plugged in a 220V socket (in Brazil 127 and 220V sockets have the same shape and it's easy to plug a 127V appliances in a 220V socket ...
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2answers
71 views

Railway overhead lines: What happens to other two phases in single phase railway power?

This is actually two questions. As my imagination I have the German/Swiss/Austrian/Norwegian/Swedish railway system on mind (15kV, 16.7Hz). I think conceptually the problem is the same on other AC ...
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2answers
100 views

Using 120 VAC 60 Hz battery charger with 50 Hz AC [closed]

I live in Australia (220-240 VAC, 50 Hz mains). On a recent trip to the United States (110-120 VAC, 60 Hz mains), I purchased some battery-powered tools that came with a charger. The charger has this ...
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1answer
68 views

Is isolation between user accessible circuits and protective earth necessary for safety?

First let me say that I understand that this question is best answered by someone familiar with relevant standards (whatever those may be). Let me give some background. When I'm designing a board at ...
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1answer
114 views

Ability of a 100km power transmission line to radiate 50Hz EM waves?

This is about confusion of relating antenna radiation theory to power lines. Assuming a straight 100km or even longer possible power transmisson line with 50Hz frequency. What can be said about the ...
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1answer
54 views

max. switching power of relay in datasheet

I want to use SPST relay to control resistive load as well as inductive load i.e. ceiling Fan (Load<150W). I used the 5VDC relay (HF46F-G) which is capable of 7A current, 250VAC. Datasheet: http:...
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1answer
75 views

tilt switch to activate power socket

I am after a way to activate a 300 W LED lamp to come on when a trampoline is jumped on and to turn off when the mat goes level again, then back on when jumped on and so forth. I was thinking tilt ...
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3answers
119 views

Switching 240VAC 1A max from 5VDC

I'm planning a device that can switch a 240VAC 1A current - most likely 0.5A but it's nice to have the head room. A relay seems the most obvious choice but given the low current it seems over the top ...
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4answers
111 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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2answers
124 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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1answer
50 views

PE pin position

I have one question. I'm designing a PCB which is a sort of smart switch (so, basically, you have one 230V input and one 230V output, where the output and the input share two wires, N and PE, and the ...
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1answer
30 views

Fusing on dual voltage industrial device

Please forgive me if this question has been asked before. I am designing a heating device that will be sold to industrial consumers. In our past designs we have had multiple versions of the same ...
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0answers
31 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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1answer
52 views

Question on Ground/Neutral connection for a 220V equipment

I sketched the following schematic from a motor controller board that has to be operated at 220V from L1 to L2. The earth wire is connected to the chassis of the machine. Where I live, it's common to ...