You can buy LEDs with the resistor already integrated.
Better to supply your own. LED's, like _most_ semiconductors, may not be wired directly in parallel. Most semiconductors have a positive temperature coefficient, which means they draw _more_ current as they heat up. Resulting in more heat, thus yet more current, and thermal runaway, and device failure. (Incandescent lamps have a negative temperature coefficient, which means they balance naturally when used in parallel.) So, for LED supplies you either need a bunch of LED's in series, with _one_ current limiter, or you parallel the LED _and_ its individual current limiter, times N, or some kind of series-parallel arrangement representing both approaches. For a 12V supply I'd stack perhaps 3 3.6V LED's in series, and use one resistor, making one 12V lamp bank. Times as many banks in parallel as you needed to get sufficient light. Remember that a simple resistor as a current limiter represents totally wasted power. Less resistors/resistance == longer battery life. More complex circuits resembling switching power supplies are not uncommon. What you are after is a constant _current_ supply, not a constant _voltage_ supply.
Certainly when I strung them up in series they wouldn't do anything...
Either you didn't wire them in the same direction, cathode to anode, or you didn't have enough voltage to push any current through their stacked junction voltages. Either will keep the photons inside... -- Jim _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
