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LEDs

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RayH

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Hi all
This may seem a silly question but I ve been asked the question and not sure of the answer, is it possible to put LEDs in series to run them of 220v ac?

I said I didnt think it was possible, am I correct?

Many thanks
Ray.
 
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You would have to use a transformer
think of it this way, if you stick a fork in a outlet what do you think will happen?.
Well LEDS usually need a voltage from 1volt to 4volts dc
and your wall has 220volts ac
that is to much volts for LEDS,
so you would need a Transformer to bring down the voltage.[/u]
 
You can actually run using AC230 without a transformer with just a capicator, but i must stress that it is dangerous as you are dealing with live voltage. Simply to a 470nF, 400V and above capicator in series with it. This way, that series will only draw around 20ma of current. But since it is AC, you will realise a flashing effect. If you want to run it on all the time, simply add a retifier & filtering cap. You can run about 90 over leds in a series but each series require a current limiting cap.
Below is a circuit to do it, but i must warn you to be extra careful with it.
 

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ym2k said:
You can actually run using AC230 without a transformer with just a capicator, but i must stress that it is dangerous as you are dealing with live voltage. Simply to a 470nF, 400V and above capicator in series with it.

One thing he didn't mention, the capacitor MUST be a special type, rated for this type of use!.
 
LED's will work on AC, but they will only be illuminated on 1/2 cycle, and they need to be protected from the reverse polarity of the other 1/2 cycle.
This protection can be in the form of a single diode in series with them.
LED's in series also need a current limiting resistor.
As it has been said before by other posters that running them off the line voltage can be dangerous if proper precautions are not taken.
But if you want to put a bunch in series to run on 220 it could take over a 100 LED's, as the typical forward voltage for Red,Yellow and Green is 2.0 volts, for White is 3.2 and Blue 3.8 volts. These voltages are at forward current at about 10mA.
The best way remains a DC wall-wart and a series resistor.
 
My new 120VAC Christmas tree lights are sixty 2V LEDs in series with a diode. No cap or resistor. Since they are half-wave and light at 30Hz, they flicker.
 
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Still a transformer would probably be the best way to go in my opinion.

Cause 220 volts is extremly high
which this person must live in Europe
and since there is that much voltage involed,
a transformer would be best for safety issue's.

Don't you guy's agree?
 
Hi GTAman,
Since Europeans have such high dangerous mains voltages in their homes, I agree that a step-down transformer would be best for safety issues, if it was used before the high voltage even got distributed throughout their homes! What were they thinking when they designed such a high voltage in homes? To save a few quid, lira, pesos or marks on thinner wire? :?: :?: :?:
Over here, we use 120VAC/60Hz to break-in big subwoofers, and the windows near them too! :lol:
Have you seen the big motors and transformers in the electrical muzeum when we had 25Hz on the mains? Just think about half-wave light flickering in those days. :roll:
 
120V (well actually 115V) can kill just as easily as 240 (well 230V)

Advantages you say? well for a given power more of it is delivered and not wasted in copper losses.

Equally we have the potential to draw alot more power from the utility for the same current.

It is all about choise. UK chose 240V @ 50Hz, US chose 120V @60Hz
 
I think in Japan it is only 100V.

In my kitchen some electrical outlets are wired with two separate phases of 120V. Then each outlet has its own 15A breaker for up to 1800W for toasters and other hot stuff. The outlets have 240V between them, like the stove and air-conditioner.

I have never tried chewing on a power cord, and think I would notice a baby doing such a dangerous act. My daughter's rabbit destroyed many power cords (I had to splice them) and it is still alive! :lol:
 
audioguru said:
In my kitchen some electrical outlets are wired with two separate phases of 120V. Then each outlet has its own 15A breaker for up to 1800W for toasters and other hot stuff. The outlets have 240V between them, like the stove and air-conditioner.

240V is very rarely fatal, you have to work pretty hard to kill yourself with 240V!, but (as I'm sure you're aware) a number of people manage to get killed from 120V every year!, never mind 240V.

The UK is no longer 240V (supposedly!), it was dropped to 230V a few years ago when the entire EU changed to 230V - the rest of Europe was previously 220V, they went up 10V, we went down 10V.
 
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It really doesn't matter about the volt's, it matters about the amps,
a wall outlet is plenty enough to kill you.

Also most thing's are made for 110 ac so they should put that all over the world.
 
It takes many volts to cause a few milliamps to flow in your fairly high resistance skin.

I think a 120VAC shock in one arm is fun. It vibrates your arm like crazy! :lol:
I have never been bitten by high voltage DC. They say your muscles contract and you can't let go. I worked with a guy whose arm caught fire when he was working on a live broadcasting transmitter! :shock:

Try holding the bare wires of a ringing telephone with one hand. Its 90V at 20Hz shakes you pretty well! :lol:
 
Re: reply

GTAman said:
Also most thing's are made for 110 ac so they should put that all over the world.

What makes you think that?, much of the world is 220/230/240V, why should we want to change to the inferior American system - complete with massive blackouts!.

I wouldn't like to guess which supply voltage is the most common worldwide, I would imagine it's fairly close? - bear in mind, that Japan uses BOTH voltages, depending where you are!.
 
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You got us there on the black out's

We use both voltage's, like to power a dryer or washer and some arc welders.
 
Let's scrap all the different standards and develop a common one for our shrinked (shrunk, shrunken?) world. Different voltages, frequencies, metric and celcius confuse everyone. Let's also even make a common language for the whole world. There is no way we will agree, it will start a war! :lol:
 
in slovene we have 220V (3 phase is 380V!)and i never got shocked by mains but i have ben shocked by my high voltage devices a cuple of times (not plesent toching an 1uF cap charged to 1.5kV!)

In school one of my frends likes to mees evriting up as much as posible and once he got in to cuting wires on an mains outlet whith papaer sisors and didnt got a shock (they had plastic handles) but then he toced the wire and got an prety nice shock and his finger was redish.

to bad we dont has such high resistant skin as moscitoes so that 220V wodnt hurt us.Snailes that are wet can get hurt by an 9V batery (its like stining it on your tung.argh!)

yep i soo hate it wen i get somting in lbs,inches...i like metric since its so easy to convert betven then(10 cm = 1 dm,10 dm = 1 m...)
 
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