help for luxeon III circuit

[Atanas Yankov]

hi
i have lambertian led
who need 3.9 V forward , and 1 A
and i can`t find pwm or other circuits .
tell me a different between pwm and constant current circuit.

 

[Hero999]

What's the input voltage?

Two threads immediately spring to mind.

https://www.electro-tech-online.com/threads/led-switching-regulator.41375/
https://www.electro-tech-online.com/threads/best-way-to-power-a-white-led.30656/

 

[ericgibbs]

hi
i have lambertian led
who need 3.9 V forward , and 1 A
and i can`t find pwm or other circuits .
tell me a different between pwm and constant current circuit.

hi,
PWM. pulse width modulation is just that.

You vary the ON time pulse period of the drive voltage.
rough examples:
if the drive on/off cycle was 50%, ie half ON half OFF the LED would run at half [50%] brightness.
If the ON time was 75% and the OFF time was 25% the LED would be at 75% brightness.

Constant current is a circuit which supplies a constant current thru a changing load.
If you mean a 'constant current' drive that be varied, then by varying the current the LED the brightness would vary.

You must stay within the current rating of the LED in CC.

Is this what you are asking.?

 

[Atanas Yankov]

imput voltage i think about use 2 battery in serial connect - li-ion each 3.7v / 2200 mA for 7.4V voltage
or Nimh battery with more current
help me for good choice a right battery - i see Nimh size D 1.2V / 10 A
but i dont know for my choise - li-ion or Nimh ?

and for supply a led - i need from last - out :
3,9 V with 1A current for max. lumen from led