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.
4
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2answers
85 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
51 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
64 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 ...
1
vote
2answers
72 views
Grounding a switching PSU with AC mains neutral
I'm working on a circuit that measures mains current/voltage. I've seen the usual setup where a half wave transformerless simple circuit is used to supply couple of miliamps of power to run the IC ...
2
votes
1answer
66 views
Dual Rectified 12V 5V Tapped Power Supply Safe?
Is the following regulator valid, safe and efficient?
The transformer is a dual 7V output toroidal. So B1 is supposed to rectify out 14v and B2 taps the "center" to produce 7V.
INAE and I've never ...
3
votes
1answer
79 views
Possible measures to make power supplies safe
I'm looking for a list of ways that mains-powered ELV power supplies with touchable terminals can be made safe in the case of transformer failure with primary and secondary coils becoming connected ...
27
votes
2answers
580 views
If we could start our electrical grid from scratch with today's technology, which would be the most efficient choice? AC or DC?
Lately, I’ve been reading about the many advantages of HVDC transmission systems for long distance transmission, undersea links, and others. The historical reason of why AC was picked over DC was ...
3
votes
2answers
184 views
Do I have pseudo three-phase power at home?
I get three live wires and one neutral from the mains. Different rooms in the house are connected to different circuits which terminate at a changeover panel. The changeover switches allow each ...
3
votes
3answers
142 views
Mains triac safety circuit design
I am investigating using a triac instead of a relay to control 250V 10A devices.
However all the 600V 16A triacs come in TO-220 packages.
According to AS/NZS 3100 and AS/NZS 60335.1 I need at least ...
6
votes
2answers
193 views
Mains to low voltage seperation between FR4 PCB layers
I cannot find clear information on running mains and low voltage on adjacent layers on FR4 PCBs. I understand how much creepage distance to allow, but for example, can I run - 50Vdc, 240Vac, 0Vac, ...
-1
votes
2answers
156 views
Multiple 2A USB Mains powered chargers [closed]
I'd like to know why there are no mains-powered chargers that can charge multiple usb devices at, say, 2A and 1A?
I'm after something that can charge 2 tablets that ask for 2A and 2 phones on 1A, so ...
0
votes
1answer
148 views
Why is using a single phase device across phases of a 3 phase outlet OK?
My friend connected two wires to two "non-earth hole" in a 3 phase outlet (208V) to run a 220V single phase blower (Note: the outlet has four holes, one of them is earth). Basically, he used the ...
1
vote
2answers
126 views
Do I copper - pour on mains voltage PCB?
I don't have much experience with designing boards for mains voltage. Now I've designed a circuit and I have lots of unused space on the board. Do I fill it with copper our leave it blank? I guess the ...
0
votes
1answer
167 views
How can I power the blue LEDs separetely on this aquarium light?
I have a Beamswork LED aquarium light like this. It has a 3 way switch:
All LEDs off
Blue LEDs on only
White AND blue LEDs on
It has a single mains power plug.
What I want to do is make it have ...
0
votes
1answer
136 views
Optoisolator always on on the high-voltage side
I am building a simplified version of this circuit:
As far as I can tell, it is a pretty standard design. The load will be a dumb resistive heater (this is a sous vide project).
For now, the ...
0
votes
1answer
95 views
How do I wire a relay board into existing series recepticles
I have a four channel relay, that I'm going to attempt to wire into a terminal block. I have experience with mains wiring and some experience with electronics, but no experience wiring relays. ...
5
votes
1answer
166 views
What is the Thévenin equivalent of the mains power supply?
Thévenin's theorem says that any voltage source can be modeled as an ideal source in series with some complex impedance. How does one quantify this model for AC mains supplies? What parameters are ...
1
vote
3answers
147 views
Could a lamp plugged into an outlet be dimmed using a variable resistor?
If you had a variable resistor connected between a lamp and the wall, could it be dimmed with a variable resistor?
Would it be practical, i.e. would it waste much energy? And would it affect both ...
9
votes
2answers
241 views
Why is mains power sometimes 110V and other times 120V?
(The same question can apply to locations with 220/240V mains, if I am not mistaken.)
Frequently I see mixed ratings indicating that something is suitable for 110, 115, 118 or 120V (in the US). I've ...
4
votes
1answer
89 views
What are good practices for traces on the “mains” side of a relay?
I'm trying to switch a reasonably sized load (800W at 120VAC), so let's call it 7A using a PCB interfaced to a microcontroller.
Obviously I need to make sure that the relay I'm using can support ...
6
votes
4answers
409 views
Validate Triac circuit
I'm designing a device to switch a heating device driven by mains power. I've done quite a lot of research and realize there's a lot of information out there but as i'm dealing with potentially deadly ...
0
votes
3answers
215 views
DIY power extension with relay
My project involves hooking up relays to individual plug points so I can control them with a microcontroller. Unfortunately, I am not sure how to approach splitting my mains 240V into 4 different ...
4
votes
1answer
145 views
Proposal for building Low-Current 220VAC Current Detector
I have been reading many such articles and have found no way to simply detect flow through a mains wire at low current.
At .27A for one LightBulb, I was calculating .05mA out of commercial 1:2000 ...
7
votes
4answers
398 views
Does appliance wattage differ by country, since the voltage does?
As an example, I have an AC-DC "wall wart" that specifies an input voltage of 100-230 volts and an input current of 0.3 amps. Since my mains supply is 230v:
Does that mean that it uses 230*0.3=69 ...
2
votes
2answers
1k views
Home Automation using Arduino and Android
I have been doing home automation for my home using Arduino and Android. I have been able to control the device through WiFi successfully.
Here is the scenario.
Since all the appliance that I ...
1
vote
2answers
320 views
Using a relay to switch between 230VAC inputs
I have two mains power inputs (in case one fails, the other is likely to still work), but the device only has one power supply, so I decided to use a relay to switch between the inputs (the device ...
7
votes
2answers
198 views
How does this continuity/mains tester work?
Many years ago I bought this screwdriver, the instruction sheet (which I have mislaid) claimed you could use it for a surprising number of tasks:
Continuity of fuses
Mains voltage present (barrel ...
-2
votes
1answer
95 views
Are there any premade Relay to Mains boards? [closed]
I'm looking for a prebuilt, safe mains relay assembly. I have relays, but I'm not about to cut up a lamp cord and solder it to the little nubbins.
I think there should be something out there that is ...
3
votes
1answer
251 views
Can I use a 240v variac with 120v?
From what I understand it wouldn't matter other than maybe the max VA would be different.
-1
votes
2answers
154 views
Creating a squar-ish wave from 240V 50Hz single phase mains a.c. voltage
I'm intersted in creating a square-ish wave from mains a.c. voltage. That is to say on the 240V 50Hz sine waveform, I would like to switch the voltage on at 45 degrees on the wave, switch it off at ...
1
vote
2answers
121 views
Is battery storage of mains power hard
I've been looking around at the different battery options for storing mains power but have found there don't seem to be a lot of offerings. Uninterruptible power supplies geared towards computer ...
3
votes
3answers
329 views
Bench Power Supply Design
I've been thinking about designing and building my own bench-top power supply for general use. I envision the primary use to be with prototyping low-power analog/digital circuits with the occasional ...
0
votes
1answer
196 views
How to tell if mains voltage is on with microcontroller?
I want to be able to tell if the mains voltage is on or off with an Arduino.
How could I do this safely with minimal components (or components from Radio Shack)?
0
votes
2answers
184 views
Mains Power indicator maximum current draw
I am building a circuit like this:
From here.
This got me wondering how much current can I draw from a circuit like this?
The question would seem to be what is the wattage of an capacitor?
Edit:
...
9
votes
2answers
348 views
What is this strange long wire for in a single induction cooking unit?
Tonight I dismantled one of those single induction hobs:
Inside there were two PCBs. The incoming mains was wired to the top left PCB, while the other contained all the low voltage components, plus ...
2
votes
1answer
108 views
What's the deal with this beamed mains transformer design?
Take a look at the image. I always understood that transformers have as little air gaps in them as possible, but you can easily look through this mains transformers that I found in China. Not just for ...
3
votes
1answer
212 views
Mains doorbell to Arduino
I'm an electronics noob and I'm looking to create a doorbell which hooks in to an Arduino board in order to alert me when I don't hear the doorbell. I've read 'Software alert when doorbell rings. ...
5
votes
4answers
1k views
When using a Laptop, is it desirable to keep it charged from the Mains all the time?
While using laptop I usually plug in my Laptop charger (i.e., from Mains power).
What is more effective - to keep Laptop plugged in at all times when possible, or some other approach (e.g., running ...
6
votes
2answers
364 views
How to measure power consumed by mains device
I would like to measure the power consumed by a mains device. I have heard that it's not as trivial as simply measuring the average current, as the device may be resistive, capacitive or inductive, ...
3
votes
2answers
984 views
How to check if something is mains earth grounded?
Suppose I would like to verify that the ground terminal on an indoor power outlet is actually connected to the ground (from what I've read, some of them aren't!). How would I go about checking that?
...
1
vote
2answers
146 views
Different design in relay load connections
(I know, relay are drawn in the wrong way, NO contacts should be in serie with load, I'll fix it ASAP)
When I have to build a board to switch many devices (mains powered), I always use a single ...
1
vote
2answers
114 views
Switched neutral option in switch datasheet
Looking at this datasheet for a mains switch, the 'preferred option' (5503 on the sheet) is called 'switched neutral'. I cannot see how both the live and the neutral can be switched with only 3 pins, ...
1
vote
1answer
111 views
How to wire AC power to an integrated DPST switch?
I have an IEC C14 power connector (like those on PC power supplies). The connector has an integrated DPST switch, however the power pins are not connected directly to the switch-- I have to do that ...
3
votes
2answers
250 views
How to detect surges in the main AC
Electronics have a habit of breaking in my house. In the last 2 years or so, I had 3 desktops, 1 monitor, 4 cellphones going dead. They are not completely dead like they won't turn on. But in the case ...
2
votes
1answer
371 views
how to interface HCPL-3700 optocoupler to an input pin of ATmega16L
I want to detect logic of the mains supply (230VAC, 50Hz) and feed the output of HCPL-3700 into ATmega16L. I read through the datasheet but could not understand how to calculate the resistor values. ...
7
votes
2answers
226 views
Isolation transformer to reduce speaker pop
I have some computer speakers which suffer from the following problem:
when switches flip in certain devices in the house, like the thermostat on a radiator or the refrigerator, the speakers will emit ...
2
votes
1answer
182 views
How to make on/off switch for popcorn maker?
I have a popcorn maker that when you plug it in it just starts working. Theres no on/off switch and it's kind of annoying. When you unplug it you always get a big blue spark which seems kind of ...
