Optocouplers for mains? Answered

I would like to know if i can use an optocoupler instead of a regular relay? Like on one side would be an arduino and on the other would be 220 v ac to control a  light for example Is this setup possible?

Question by akinich   |  last reply


Main Image?

I'm trying to upload a video and everytime I do it tells me that I do not have a main image. I have a profile picture but don't know what else that would mean?

Question by leah.skelton   |  last reply


Main Image

When I created this instructable https://www.instructables.com/id/The-Highway-Paracord-Bracelet/, I used the first image(of this question) as the main image. I have a better image now and would like to change it. I tried changing it, but it only shows it from inside the instructable. It doesn't show it from the search. Please help! Thanks

Topic by BenjiDaa   |  last reply


Mains Beer?

My head occasionally says "what about mains-beer?". Instead of buying stuff to take home, you have a beer-tap on the sink. Here is how it might work: You build a distribution centre, which may just be storage, but could also be a brewery, and run pipes around a nearby residential area. Each home has a beer-meter like a water-meter which is data-linked to a consumer-unit on a beer-tap on a sink. The distribution-point provides mains-beer under gravity, consumption of which is measured by the meter and data is fed to the consumer-unit. That box displays beer consumption, and via a radio-link informs the distribution-point. Periodically the lines will need to be flushed, here's how that would work: > The centre switches the supply from beer to water, which is coloured with a harmless-dye, and radios the consumer-units which display the message "free beer" whilst playing Happy Hour. Consumers vigorously empty the lines while it's free. When the water hits the meter-unit an optical-sensor calls the consumer-unit to shut off via a solenoid-valve, the consumer-unit reports back to the distribution-centre that water has reached it. After a set period the distribution-centre radios the units which haven't yet reported water to open (solenoid). Any units failing to give an adequate response within a reasonable period are radioed to display a "fault" message and flagged for a service-visit. The distribution-centre then switches supply to cleaning-fluid, and messages all consumer-units to display "cleaning!" and open up (solenoid). Once sufficient flow has gone through each meter, they shut off (solenoid) and radio-back. Then a water-flush follows in a similar way. Once the lines have been cleaned, the supply is switched back beer, the consumer units run until they no longer read "water", plus a bit more to clear dead-volume between meter and tap. Then the consumer-units display "read to dispense fresh beer". Pros: Beer is chilled by the ground in which piping is laid No packaging-costs (cans / bottles / kegs) Less transport costs Drinkers have an almost unlimited supply enabling them to drink more than they might otherwise. No more beer runs when the game runs long or uninvited guests show up (Re-design) Consumer units can display total quantities dispensed, with cost and "don't you think you've had enough?" Cons: Initial infrastructure cost It'll work best with poor quality-beer Well?

Topic by lemonie   |  last reply


Computer fan to mains?

Our offices were shipping up to move to a bigger branch. and there was loads of gear left over, i was most interested in a computer fan, and thought if there was a way i could get this to run off the mains?? I am unsure of the make model etc.. but any ideas would be helpful, i don't know why i am doing this i just try daft little things sometimes. I've been looking for a site like this for ages!! lol. It's UK mains incase that helps? would an old phone charger work? Any suggestions?

Topic by Monkey1988   |  last reply


Playing with mains electricity

I'm of the belief that most of us have played, in some form or another, with mains electricity. Whether it be fixing the power cord we accidentally cut in two, or juicing up a computer psu... So. I'm wondering if any of you have an electrician's licence. Reason I'm asking is that in Australia, doing anything with mains power requires one. Playing with power sockets, power plugs or cords, installing lights etc. Firstly, do you have this problem in the US? I've seen a few projects which involve light fittings and licence-requiring activities, and I have to wonder whether you're all licenced to do this sort of thing, or whether you're all licenced. And just thinking that there could be a potential loophole in the regulations... If you hooked up two ac transformers to step down the step back up, so you're where you started, technically, you're not running off mains power... if you get my drift. anyway. you all ignore this little aspect of the law or what? cheers

Topic by infiniteregress   |  last reply


Power 2 LED's

Basically I want to power these 2 LED's from mains power for an Instructable, i have no idea where to start, please describe in laymans terms, any help greatly appreciated cheers

Topic by abitdifferent   |  last reply


Leds To Ac Main 220v ?

Hello i want to build leds that work with ac main 220v i am fond of the leds . i want to glow up one led  with few components with full brightness ? sorry for my english . thanks in advance ?

Topic by malik8801   |  last reply


Trying to convert a mains powered string of LED's

Hi, I purchased a set of Xmas lights believing them to be 'low voltage'.  My plan was to run them from the caravan 12 volt DC.  However, it appears that they run from the 230 volt AC mains.  This is something I am not familiar with. I have attached my own wiring diagram of the circuit and would like to know if anyone can tell me how to switch the four strings of LED's individually.  I have an inverter that I can use as the current draw will be minimal. I imaging that the LED's are wired as opposing pairs so that both halves of the mains sine wave are used.  Presumably, this prevents the set being run from 12 volts. Any help will be welcomed. Alan ...

Question by newalfi   |  last reply


Is there a simple way to be able to run low voltage things like LED arrays from the mains power?

Basically I want to be able to make some LED lights to light up my workbench in my shed and it'd be easier if I could just plug them into the wall instead of having to replace batteries every now and again.

Question by Building Books   |  last reply


Which Components to use? Answered

I want to make a circuit that is powered by 220v ac. It consists of a cooling fan that requires 12v, 0.7a, a  PCB with 10 LEDs in parallel that requires 0.25a, 3.5v and a single led that requires 3.5v,0.025a. I know how to calculate resistor values but it would be better if you give the values. I want to know which diodes should I use to make the rectifier and should I use a capacitor? In short, I want to know  how to set up this circuit, what components to use and their value and power ratings.

Question by Ahtasham Ahmad Mohtashim   |  last reply


How to get a main picture? Answered

How to get a main  picture like Hiyadudez? here is the link to his page https://www.instructables.com/member/Hiyadudez/!!!!!!!!!!!!!!

Question by TSC   |  last reply


An instructablers dream property in Maine

Totally random posting, but when I saw this Maine property listing I immediately thought it would be a haven as a DIYer commune.http://maine.craigslist.org/rfs/704764214.html

Topic by susie   |  last reply


Main site is all blank

Is anyone else getting this problem? I go to the main site, www.instructables.com it is snow white, no text no pics, nothing. The only way I could get here was to google instructables and  click on a link to a part further inside the site.

Topic by jack002   |  last reply


Powering LEDS with mains power.

What if you made a voltage divider with high-value  resistors, and then rectify the signal?  Is that dangerous?

Topic by flagrantfouler   |  last reply


The main image picture dimensions?

Hi, there friends i have some projects going on here and i was wondering the first image of an instructable what are the dimension, because i tried many sizes and all get shopped and they don't look nice.Thanks 

Question by NoskillsrequiredN   |  last reply


Powering LEDS with mains power.

The idea is to use a voltage divider with high value resistors and then rectify the signal.  Is this dangerous?

Topic by flagrantfouler   |  last reply


Search engine @ main page

Hi I'm using 1. a laptop, ubuntu 12.04 LTS, 2. Chrome vers. 36.0.1985.143 3-5. The last couple of days I haven't been able to use the big search engine at the main page with all its suggestions. As soon as I click the box to enter my search terms, I'm directly transported to whatever suggestion is coming up, such as beer or the alphabet. This was something I could do at the latest last week. The positive part is that I found the small one in the upper right corner after several years as a member. Got kind off invisible with the main one being so big. Keep up the ever so great job You're doing! Kind regards Oscar

Topic by Osquar   |  last reply


Dimmable Mains LED lamps? Answered

I have changed all my internal lamps to 240 volt LEDs - I notice some LEDs are dimmable and some are not any one know why? As a supplemental  question anyone know how they step down the 240 volts for the LEDs? I have yet to take one apart to see.

Question by rickharris   |  last reply


Conputer only boots after a replug, help? Answered

The computer boots fine if i unplug the mains then replug - it will then boot perfectly normal, once i turn it off tho it just refuses to turn on, doesnt get to post (screen stays black), so i have to unplug it again and it works fine... have tried different PSU's, CPU's and ram, out of ideas

Question by Ralim   |  last reply


How do I wire this AC motor to a UK plug? Answered

When wiring this 220V, 60rpm AC motor to the mains, it turns perfectly with the live and neutral wires connected to terminals 1 and 2 and with the earth wire disconnected from terminal 3, however it does not turn when the earth wire is connected to terminal 3. How do I resolve this when wiring it to UK mains?

Question by CassiaD   |  last reply


Mains Ground Safety for Power Supply? Answered

I'm trying to build my first switched mode power supply. I'll be using it to drive two 24v 50W heating elements. I don't want to use a transformer. The design I have so far seems to work well in simulations, but I need some advice regarding mains ground. The control electronics will be operated on power from a small transformer. This provides isolation from mains. I've done this a million times.  However, the mains power connects directly to the loop that produces the 24V signal. This is the loop after the FET, containing a diode, inductor, and capacitor. The wire coming from this loop and going to the comparator is where I'm having trouble. This is a voltage sensing wire and carries very little current, and is used by the comparator to produce negative feedback. This feedback loop is what allows me to get 24V from 120V. The comparator is powered by the 12V isolated supply. In order for it to sense the voltage properly, the comparator's ground must be at the same voltage as the power supply's ground. But the power supply's ground is tied directly to mains ground. Is that safe? Am I allowed to do that? In mains wiring in the US, the left notch is neutral, the bottom hole is ground, and the right notch is hot. Neutral is basically ground, except ground is connected to the actual ground and neutral is this mysterious thing I probably don't completely understand. Is it safe to use it as ground? What if the person using this circuit flips the plug over and suddenly the circuit's "ground" is fluctuating wildly between +/- 120V? The circuit may function just fine, but someone using a switch or knob connecting to ground could get a nasty shock. How do I make sure the ground of my circuit is always connected to actual ground? Do I need to preserve the isolation of the control circuitry? I know how to use Gate Drive Transformers for the FETs, but the sense wire for the comparator still needs to have both halves of the circuit with their grounds at the same voltage. Any advice is greatly appreciated.

Question by laserjocky   |  last reply


Can I use rectified mains power for electrolysis? Answered

Assuming that I properly insulated the system, would it be practical to use mains power in a hydrogen generator? It seems to me that it should be feasible, but I've heard from some people that hydrogen generators work better at lower voltages. If I could use mains power, would I have to limit the current in any way?

Question by Shagglepuff   |  last reply


Using a microwave oven's timer as the mains timer switch?

I have a timer switch from an old dead microwave oven. Can I use it as the mains timer switch? If yes, how do I connect it. The timer looks exactly like what is shown in the following picture: http://hackadaycom.files.wordpress.com/2013/09/mads-microwave-teardown1.jpg (The picture was not taken by me. It is from an article on useful things that can be harvested from  dead microwave oven.) Also, if possible, please mention the functions of various pins or give a link to an explanation.

Question by raftor   |  last reply


I tried to create a 2 led driver from the mains. Can you please check it? Answered

(This is just an experiment) The first circuit failed due to my mistake of using polarized caps. I replaced it with non polarized now. Can you please check if it would work? I don't want a loud explosion again :) Capacitors: 0.47uF 250V LED: 3V White Diode: 1N4004

Question by codestroy7   |  last reply


Why does the battery level going down, when there is no battery installed?

Hi, I have a 7" tablet, which battery got a damage, and stopped working. I replaced the battery with an USB cable, and plug it into a 850maH phone charger. First of all, the tablet keep saying that there is an over voltage in the battery. I assume its because I have 5V instead of 3.7V. I don't know if i could cause some problems in the future or not. Second: if I connect some other mobile charger like a bigger one, the screen stops responding, or goes crazy. I experienced something like this when charging an old phone. Possible causes? Third: the most interesting thing is, that my tablet says its battery is draining. It is mostly constant, faster when screen is on, even though there is no battery in it... If you guys have an answer to any of these questions, I would really appreciate your help. Thank you in advance, Leslie Spike

Question by Sp1k33   |  last reply


Converting mains power to battery power?

I have plans on building an electric go cart, however, the only motor I currently have is mains powered, as such I was wondering if anyone knew of any ways to convert mains powers to battery power, hopefully car batteries as these would be what I using. I've searched high and low and can't seem to find anyone that has done this, let alone a tutorial. Anyone with any idea's or links would be very helpful. Thanks in advance.

Question by ads100   |  last reply


is it possible to use lm78xx to regulate electricity from the mains?

What if i use capacitors to lower the voltage from the mains, then rectify it. Is it possible to use any member of lm78xx IC family to regulate it?

Question by codestroy7   |  last reply


Rewire car charger to UK mains electricity socket

Hello there, I have a 12V air compressor pump which I would like to use inside the house. It's designed for pumping up car tyres, so it has a car cigarette lighter plug, but I think it would be useful for cleaning out the dust from my computers. I've seen a few mains adapter converters on the internet, but none of them have the required amperage (16 amps). I've decided it would be more useful to convert it to a mains plug instead. My knowledge of electronics wiring is poor, but I'm a dab hand at tutorials, I just need to know where to start! :) Would anyone be able to give me some advice? The device is here if anyone wants some background: Thank you! James

Topic by James_B   |  last reply


Putting an end to flickering LED's on mains

Greetings everyone! It's the time of year when colorful twinkling lights adorning nearly every structure you can see. LED's have become more popular as of late, and from an energy standpoint that's good. I know most people can't see a 60Hz flicker but I can, and it's quite unpleasant to sit across from a tree full of LED's all doing the same on-off-on-off nonsense.  I am fortunate to only get headaches though, other epileptics I've known have actually had AC LED's trigger seizures. So what can be done about this? We bought LED strings before thinking about flicker and have since replaced them with incandescent ones, but I've still got all the LED strings in the closet. I'd really like to be able to use them.  Perhaps I could fashion a device that acted as a middleman between the outlet and the plug on the lights that would smooth the incoming current? I have two ideas for this:  1.  Filter incoming current with an RC circuit 2.  Rectify the mains voltage I'm curious if anyone else has attempted, solved, or even just noticed this frequency problem? I don't mind re-inventing the wheel, but I'd rather not build it square. Happy holidays! **yes, I just said happy holidays. Deal with it. :)

Topic by Electron_flow   |  last reply


Is it safe to hook this transformer up directly to the AC mains? Answered

I bought an old high voltage transformer from the internet a while back. It seems to work well at AC frequencies (anything higher and it doesn't work at all), and can make some pretty good arcs. When hooked up to a power outlet with 360 ohms of resistance in series with it, it produces a 1.3 cm blue arc. When using a 30 ohm resistor, it makes crazy arcs with a bit of orange (I'm using four 5 watt 120Ohm resistors in parallel, and they still overheat). None of these tests caused the transformer to heat up at all, though. Would it be a good idea to directly hook up the transformer into a power outlet? Would it burn up the transformer and/or my house? A couple other things about the transformer: The primary has around 2 ohms of resistance, but I don't know anything about its inductance. The whole thing is pretty hefty and has a fat iron core. If you brush a wire from a 12 volt power supply across the primaries, you can get a nice spark c: Any help would be appreciated. 

Question by Shagglepuff   |  last reply


Power a DC motor with UK mains?

What is the simplest way to connect a small 6-12V DC motor to 230V UK mains supply?

Question by CassiaD   |  last reply


main image doesn't look as it is supposed to be?

I have publish 1 instructable whose main image was 3MP (2048*1536) and of 738 kb, but when i see into recent instructables only corner portion is visible ( instructable was food item but only some part of dish is visible) can you help?? now through edit option i can't change main pics view (though in instructable pic is full)

Question by prachilele   |  last reply


Main page showing older instructables

Hello all, Is anyone else having this issue? When I go to the main page it just shows instructables that are old. There are no new ones listed. and when I try to click the "recent" button, It hangs on a white screen. I am using a mac computer running windows 7 64 pro with fire-fox all updated.

Topic by SlickSqueegie   |  last reply


Efficient House in Maine has no Furnace

This house in Maine has no furnace and will generate more power than it uses. With some extreme air-tightness and solar panels this is one super efficient house. It even has mood ring-style lights on the side to let you know how it's doing. Green is for Net-Zero use, yellow is on the border, and red for pulling more from the grid. Linkvia MAKE

Topic by fungus amungus   |  last reply


velleman 8055 pc to mains light

Hi all, I would like to know if any of you would like me to upload my plans on how to use the velleman 8055 board to switch on your mains lights? This is a simple example of how to automate your home from your own PC. The applications for this are endless as long as you can program in Visual Basic.

Topic by johnkj   |  last reply


Bug while searching main page

Hello,  I am using Google Chrome 26.0.1410.43 m on Windows XP I was on the Home page trying to search when you type in the search bar the characters are invisible. They are only visible if you highlight them. Sorry if I am a little short to the point but I am half asleep.  Thanks Conrad

Topic by Pfarmkid   |  last reply


Change 'main' picture of old Instructables?

I have made a video that describes my problem very well, Id appreciate it if someone could give me a solution.

Question by DELETED_Blue Mullet 2   |  last reply


How to Change Main/Cover Photo

Hi I had published an instructable before. Now I would like to change the main/cover image of it. How do I do it in the new editor? Once before I changed the main photo going to publish and I lost the comments I got. I did it the wrong way. Is there any other way in the new editor? Thanks in advance

Topic by Passion Make   |  last reply


Help needed - I'd like to run some mains powered led lights from battery instead and control remotely?

Hi all and thanks in advance for taking the time to read this plea.... Here's a bit of background to the project I'm trying to undertake. My wife and I recently got married and as we met many years ago working on a cruise ship, my family decided to commission a model builder to build a replica of the ship we met on. Wonderful! We've mounted it on a shelf on the wall half way up our stairs as it's the only place in the house it fits. My only problem is that is has a set of lovely white led lights built into it with a cable coming out with a plug on the end. There's no easy and elegant solution to get power to the shelf where the ship is and I can't access the lights to swap them for a battery powered set as they're sealed within the model. I figured that it may be possible to create a battery pack to connect to the lights instead of the plug. As they're leds, I assumed (and we all know what that leads to) that they may be low powered enough to run off batteries.  The other thing i'd really like and i have no idea if this is even possible, is to to have them turned on and off remotely as reaching the shelf to switch them off will be quite tricky as it's very high up. I don't have the first clue where to start. I am attaching (if I can work out how to do it) a picture of the plug that I have removed from the lights to hopefully give someone a clue as to the power requirements of the lights. Any and all help would be greatly appreciated. Thanks again in advance. Mike

Question by mikepalmersinger   |  last reply


Charging capacitor from rectified mains? Answered

Recently my father brought 2 6400uf 400v phillips from his work. i want to charge it with rectiried mains. will be using them in paralell for coilgun  1) what is the voltage of 220v mains when rectified?(my voltmeter bunt) 2) when i try to charge them directly from a rectifier it melts my wire due to current. unfortunately i donot have a high power resistor to limit the current. How can i solve this without buying a high power resistor? 3) I want an led to light up when the voltage from the rectified mains is attained. 4)what will be the best. a 55 amp relay or a 75amp switch. i know that the switch can handle much more current but will the switching be quick  enough?   thanks in advance.

Question by ARJOON   |  last reply


Can a polypropylene water main be repaired.?

I wanted to tap into a polypropylene water main.  I had some previous experience with this type of pipe in my city.  I tried to used a PVC barb fitting coupling with SS hose clamps.  But these pipes have been in the ground in my city about 30 years.  The pipe seems to be brittle with age.  I had to  use a torch to get the previous 1" pipe to slip onto the barb fitting.  It held for about 2 months, then split and began to leak at the repair.  My plumber friend tells me his company will not touch these pipes.  They just replace the whole water main with copper pipe (for about $2200!).

Question by fixallmike   |  last reply


12VAC to 12VDC by using 4 ini4007 diodes? Answered

I want to convert 12 v ac to 12v dc i have a transformer to step down 220v(my mains voltage) to 12vac now i want to use 4 ini4007 to convert that voltage to a stable 12v dc is it possible Thanks

Question by TheGreatResistor   |  last reply


why are cellphone chargers so small?

I was thinking what kind of transformer are in those cellphone chargers. their output are so high considering their very small size. is it possible to use audio transformers to step down mains AC? if yes, is it safe? my professor gave us a very simple project - to make a power supply. of course i will use a transformer. when i pass my project she told me that i used a audio transformer. i don't know that the transformer was an audio transformer because it was labeled 220v 50Hz to 9v 200mA i searched my area for transformers i found several with identical ratings but they are significantly larger. my conclusion is my transformer was small due to the fact that it is an audio transformer. when i searched for audio transformer i found a lot of very small transformer. now, is it safe to use those very small transformers to step down 220VAC mains?

Question by codestroy7   |  last reply


how do I make a light up power socket?

I need a method for including a light in a socket so that it turns on when there is a current running through it, anybody know how this can be done>?

Question by Nayr   |  last reply


Where can i find information about how modules that run through the mains work? Answered

Do you know of anywhere on the tintermaweb where i could find out how theses modules, such as x10 or ethernet wall plugs, work?

Question by pyro-jim   |  last reply


How can I modify a basic mains timer switch (non-digital) to work with DC?

DC timers are extremely costly compared to their AC counterparts and can be very complex. I'd essentially like to modify one of these guys to work with DC, plugged in a circuit, instead of the wall outlet. Here's an example of the timer switch stuff I'm referring to: http://www.dbjholdings.com/images/300x300/5022822160514-3-1.jpg So... how can I do it? I'd like ot to accept a wide range of input voltage (12v to 32 but 20 to 32 would also work if it makes it easier) Thank you guys!

Question by atkers   |  last reply


How is a large building wired up? Answered

So, recently, I was at school, and trying to use my laptop charger ( I was the only person in the room to be doing so) However, it didn't work. Using it at home, however, it instantly kicked the RCD or safety switch thing off, switching off everything running off the mains Upon further inspection, I found that the power cable had been damaged, so that the active wire was in contact with the ground wire. My question is, how come the power at school didn't get shut down completely ( the lights were still on, and wall outlets in other rooms around the school still worked) but at home, everything was completely shut down. I thought that there'd be at least a fuse or something, if not a safety switch...

Question by .Unknown.   |  last reply


Microwave transformer electromagnet?

Hi so I was bored and decided to make an electromagnet out of a microwave transformer by taking the secondary off and keeping the primary. I hooked it up to some 9v batteries and stuff but it wasn't that strong so I researched it a bit and found out you can hook it up to the transformer input voltage (which was 240v AC) so I did but when I turned it on it made this very loud buzzing noise and I thought I saw what looked like flame in the socket. I turned it off imediately and unplugged everything. Whatever the magnet did must of been strong because it broke itself apart slightly. I tested the sockets with a multimeter and they still say 240v but I just want to make sure I didn't do anything bad to it. Also did anything actually go wrong or was this all meant to happen?

Question by jlandreth1   |  last reply


Some LED Projects !!!

. You can see my LED Projects: https://www.instructables.com/member/pandyaketan/ reg ketan

Topic by pandyaketan   |  last reply