getting the maximum out of LEDs

How is it best to connect led's . . .

what connection keeps all leds light at the same brightness??

what connection led's need be connected to bright most??

Thank you for who answers my question

well generaly leds have a range they can run at and the like to run at the average, but can run higher which probably reduces the life of them, now some ppl say u can run up to 4 or 5 leds off one resistor, maybe u can get a little more acurate with power ratings but if u want all of them the same brightness u would be better of running a resistor on each led or 1 resistor for every 2 leds. that is my opinion

Heres a real simple circuit that uses and adjustable voltage regulator as constant current regulator. When using a constant regulator the voltage can vary without the led brightness changing. This is useful with white LEDs since their brightness can vary greatly with a small change in voltage. Plus you can add LEDs in series without changing the resistor value. You can still get LM317 regulators at radio shack.

The only limitation is that the total foreword voltage of the LEDs in series must be at least 1.5 volts lower than your battery voltage.

A worked example for 3 typical red LEDs:  LED foreword voltage = 2.2, current = 30mA

For the resistor, 1.25/0.030 = 41.6 ohm.  And at 12 volts you can drive up to 4 LEDs.