Yes, they get hot very quickly without heat/termal sink.
This seams to be a versaltile pice, voltage in/out and current is adjustable, and price delivered
about 3 euros. But again no idea about the quality....Instructions in totally not understandable chinglish..will order a few to test.
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fun on a boat is inversely proportional to size...sort of anyway
Thats the best simple way to do it, a simple current sink from a 317 chip.
a resistor will work but as battery voltages varies from 10.8 to 15 volts (worst case) you wont have a very stable light output.
just look at the Vf/Current for an LED, they are more or less a voltage reference, therefor must be driven by a constant current. a resistor is a very bad way of doing this . (unless you have a very big resistor and high voltage battery!!
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I am usually not as green as i am cabbage looking.
