Dblock Posted January 9, 2011 Share Posted January 9, 2011 I have a question about smd led's. I want some smd led's and most of them are 12v DC and come with 2 wires. How would I wire this up or what could I get so I could plug them into 3 pin mains at home? Thanks Quote Link to comment Share on other sites More sharing options...
Stu350z Posted January 9, 2011 Share Posted January 9, 2011 Go to Maplin/Fleabay and buy a "Step Down Transformer!!" (Its What us old folk used on our train sets!) Make sure you buy the right one! IE I've got no idea but I'm sure you could find out! Maplin for Geek Advice then Fleabay for Price!!! Sorted! Quote Link to comment Share on other sites More sharing options...
Dblock Posted January 9, 2011 Author Share Posted January 9, 2011 Cheers, if they had a plug I could get a converter but it's just 2 wires. Il have a look for the step down. Cheers Go to Maplin/Fleabay and buy a "Step Down Transformer!!"(Its What us old folk used on our train sets!) Make sure you buy the right one! IE I've got no idea but I'm sure you could find out! Maplin for Geek Advice then Fleabay for Price!!! Sorted! Quote Link to comment Share on other sites More sharing options...
Husky Posted January 9, 2011 Share Posted January 9, 2011 SMD means surface mounted device, they are the type that are soldered directly onto circuit boards and dont have wires trailing from them. The most common type of LED is 5mm. for simplicity look for ones that already have the correct resistor for 12V (or whatever voltage you want to work at) attached with wires to connect up with. for a power supply you can go shopping at maplin or ebay as suggested for a 12V or 5V or whatever rating you want to go with. They will have a mA rating aswell but if you arent using many LED's it barely matters about this. There are other things you can use but i dont want to go telling you to stab wires in random plugs. Quote Link to comment Share on other sites More sharing options...
Husky Posted January 9, 2011 Share Posted January 9, 2011 oh, and the LED's have 2 wires because they only have a +ve and -ve. where as the plug in your home has a +ve, -ve and earth (to protect you from zapping yourself) Quote Link to comment Share on other sites More sharing options...
Dblock Posted January 9, 2011 Author Share Posted January 9, 2011 Just the man I wanted to hear from. These smd LEDs are quite cool. The run at 12v I take it 5v would be if I wanted them dimmer? These are also 5mm flat tops which IMO look better than round tops although they will be hidden only the light will come out. Is there any particular LEDs that are better or brighter than others as I'm using it somewhere well lit anyway. Il be going for a strip around 5m. Thanks Quote Link to comment Share on other sites More sharing options...
Dicky Posted January 10, 2011 Share Posted January 10, 2011 Go to Maplin/Fleabay and buy a "Step Down Transformer!!"(Its What us old folk used on our train sets!) Make sure you buy the right one! IE I've got no idea but I'm sure you could find out! Maplin for Geek Advice then Fleabay for Price!!! Sorted! It’s about 40yrs since I studied electronics and things have moved on a pace since then so I hope this will still be valid. Led’s are a dc devices with +ve and 0v connections, so a step down transformer on its own wouldn’t be sufficient as the lower voltage output from the transformer would still be ac. You would now need to convert it to dc by rectifying it with a bridge rectifier. Something in the order of a 9v ac output from the transformer, when rectified, would give approx 12v dc. Before connecting the led to the dc output you would need to know the forward voltage and current of youre led in order to calculate the correct size of resistor to protect it (by connecting the resistor in series with the +ve connection of the led to limit the current that would flow through it) Hope it helps and is still current Quote Link to comment Share on other sites More sharing options...
Husky Posted January 10, 2011 Share Posted January 10, 2011 Just the man I wanted to hear from. These smd LEDs are quite cool. The run at 12v I take it 5v would be if I wanted them dimmer? These are also 5mm flat tops which IMO look better than round tops although they will be hidden only the light will come out. Is there any particular LEDs that are better or brighter than others as I'm using it somewhere well lit anyway. Il be going for a strip around 5m. Thanks i would probably suggest for simplicity to get premade stips of LED's which you can also buy power supplies for that match. this makes it nice and simple to get them put together. also they will give you the correct spread of light. Quote Link to comment Share on other sites More sharing options...
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