best to put an inverse parallel diode across the LEDs too,
and an inline fuse so if the supply get reversed the fuse goes not the LEDs
regards malcolm

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LED Headlamps and Sea Fishing UK
http://www.geocities.com/malc_hurn
http://groups.yahoo.com/group/seafishinguk
http://www.brockstock.org.uk


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for my LED lights I use a cluster of four Sunbrite mini-wedge 10mm LED
lamp replacements. The Sunbrite mini-wedge LEDs are packaged to
replace a 12V bulb and hence have the appropriate current limiting
resistor built in.

I parallel the cluster of four together, then pot them and the power
cable in a waterproof epoxy resin. The waterproof resin, which I use
is not clear, so I leave the top 1/4" of the LEDs protruding. Each LED
produces 1600 mcd with merely 20ma of current draw at 12 VDC.

The Sunbrite LEDs are available in clear, yellow, red, green, and blue
for $1.60 each (I buy them from Digkey). I use two of my cluster
lights (of the blue ones) to illuminate my waterfall.