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Id like to use 100(ish) of these to create a 'starry' effect on the ceilings of my childrens bedrooms.
http://www.maplin.co.uk/module.aspx?moduleno=35738#features
Can I just use a 12v transformer as used for low voltage lights?
Are the leds wired in series or parallel?
Presumably I need resistors somewhere? I just dont have a clue where, or how to work out what values I need.
Any pointers appreciated.
Yep you just need a 12 volt transformer and a lot of patience 🙂
Wire them in parallel, and the transformer has have at least 12W / 1 amp of power.
Hmmmmm , 120W X 100.
You could grow a good crop under that 😉
Hi,
The Maplin link says that they have integral resistors, so you do not need any extra ones. Each LED takes 8.5mA so 100 will need 850mA, hence the 1Amp (1000mA) mentioned above. Parallel is the way to go.
However a simple 12V transformer will also apply a reverse that will exceed the 5V limit on the LEDs. The fault current will also be limited by the integral series resistor, but I would still not be using a simple transformer.
Some thing like [url= http://www.maplin.co.uk/Module.aspx?ModuleNo=96864 ]this[/url] may be better as it will give you DC, rather than AC.
Sounds like a fiddly task that you have set yourself!
cheers for the replies. I've actually got one of those adaptors knocking about Labwormy, never thought of using it though. 🙂
What Ian Munro and LabWormy said. The 12v 1A DC power supply doesn't have to be regulated though. An [url= http://www.maplin.co.uk/Module.aspx?ModuleNo=46107 ]unregulated[/url] supply would have been ok.
Make sure you wire the LEDs the right way round. Their max reverse voltage is only 5v so you could blow the whole lot if you get your +ve's and -ve's mixed up!
maybe worth considering putting optical fibres in, only need one light source, and it can create different effects.
e.g.[url= http://www.crescent.co.uk/downloads/images/fo_kits.pdf ]optical fibre[/url]