Adaptor For Christmas Lights

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My girlfriend has bought some reduced lights at B&Q because they had no adaptor.

They were in the reductions with the Christmas lights but are not Christmas themed as they are flower type decorations. This being so she wants to put them up at home.

The label on the lights says 4.5Volts, max 1.8 watts.

I found an old adaptor at home (which I think was for an old personal CD player). It has the output listed as 4.5V, max 6 watts.

Am I correct in thinking I could use this adaptor if I wired it up? Does it work in the same way as garden lights in that as long as I don't draw more than 6 watts off the adaptor then it would be ok?

If it can be used then as well as having the polarity correct I would need to figure out how to wire it up as both the adaptor and the lights have a male end. Other than cutting wires are there any female to female couplers available? (The connections are of the usual round sort that are common on multi voltage adaptors).

Thanks in advance,

Daz
 
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Yes, yes and yes.

Polarity shouldn't be a problem - usually the middle pin is positive.

You can buy couplers from places like maplin, but make sure you get the right one (the pin diameter varies you see, so look carefully). It may be easier just to chop off the ends and choc block them together.
 
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Assuming no AC/DC mismatch.
True, in which case we'll have to teach him how to build a bridge rectifier.

ban-all-sheds said:
it should be checked out, or the lights (my guess is LEDs) may be ruined.
It can? I've never seen a diode fail in service owing to attempting to pass nominal current the wrong way.
 
LED's don't fail, they just won't light up unless Pos and Neg is round the correct way.
 
LEDS have a much lower peak inverse voltage than normal diodes, typically only a few volts. They can easily be destroyed by incorrect polarity.
 
LEDS have a much lower peak inverse voltage than normal diodes, typically only a few volts.
Usually 5V. We've only got 4.5V here.
Red LED's are normally around 1.2v I used these with standard 7812 voltage regulator to boost output to 13.2V however different colours are different voltage.
To run on 4.5v it would need some current limiting resistor which is often built in.
 
Just to add if these are led then there may have been a control box?
Personally I would plug your adaptor in the leds should be ok at 4.5v but if unregulated you might have problems by connecting the wrong way. Have you got a meter?
If you give us a piccy people will be able to get a better idea what you have got and what you will need to drive it!
 
Thanks all I will try and get a photo of the lights later on.

ban-all-sheds wrote:
Assuming no AC/DC mismatch

Excuse me being thick but what does this mean?

Thanks,

Daz
 
Does the adaptor which should have come with the lights output AC or DC?

Does the one you are thinking of trying output AC or DC?
 
Just to add to BAS's point, a lot of the time AC isn't written but is represented by a sine wave ~ , and DC by two lines atop each other (kinda like an equals = sign), but the bottom one being dashed.
 
Easy way to tell if the lights need an AC or DC transformer is.....If a few inches after the transformer connection on the lights there is a little moulded blob, this will be an AC to DC rectifier which means you need a 4.5v AC transformer, if not you'll need a 4.5v DC transformer. If there is a multifunction controller then its not as easy, but all the info you need should be on the label attached to them. If you can take a pic of that and post it up the guys here will be able to tell you everything you need to know.

All the best
Dan
 

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