Re: Project help with magnets
I am trying to make a light with LEDs on a magnet, I'm wondering if a magnet 1-2 inches in diameter mounted to a metal wall will have adequate heat sinking ability for 3 Lux III or Lux V LEDs. I'm also wondering if there is any reason I can't drive them from a straight AC/DC adaptor (12VDC/600ma). I may later power them with Nflex for dimming capability but would like to see how well they would work first.
Not sure if magnets conduct heat well, but here are some things to think about:
A thicker wall will be better than a thin one, but I think this matters the least.
The most important thing is paint/coatings; these will reduce the ease with which heat can transfer to the wall from the LED's. If it's bare metal, this is best. If you can get a stronger magnet, this will hold it to the wall harder, and so increase the heat transfer. If you can get thermal gunk on the wall (bear in mind it's VERY messy) then this will fill in all the defects in the surfaces, greatly increasing energy transfer.
If you have a bare wall, then you should be fine. A painted surface would be bad (and the heating of the paint would probably destroy it fairly quickly anyway). Any others from the list above you can add would be beneficial to energy transfer to the wall, but may not be necessary.
A problem with AC-DC is that the DC they create isn't real DC (batteries are the only way to get perfect DC). You can get some AC compatible drivers (some original buckpucks do this), but drivers likely to be damaged by reverse polarity inputs should be avoided. I may be making a fuss over nothing, and chances are your LED's will be fine with a bit of reverse polarity (who hasn't connected them wrongly to a battery?)
