### 11Simple LED driver using LM317 regulator

This Led driver is very easy to construct since  you will need only 2 electronic parts, the LM317 IC regulator and 1W resistor. Driver can be powered by any 9 to 20V DC supply. Circuit can drive any  LED ranging from .5W up to 5W by just replacing the value of resistor depending the allowed current specified for the LED using the formula shown below : ( no need for LM317 Calculator).
R =1.25/current(I);    where I is the current specified by LED datasheet
For example:
700mA current is needed to power up a 3W LED, you will have:
R=1.25/0.7A=1.785 or around 1.8-ohms
 LED driver circuit
Part List:
1-LM317 regulator
1-resistor
-3.9-ohms for 1W led
-1.8-ohms for 3W led

Other LED driver:
1. LED driver using 7805 – one of the cheapest and simplest driver, similar to this driver
2. Cheap Power LED Driver circuit – cheapest, uses only resistor, transistor and diode
3. High current LED driver using FET – stable and  high current led driver

Note: The maximum current of the LM317 regulator is around 1.5A only. Don't forget to add heatsink in the regulator to avoid damage due to overheating. When the DC supply is not regulated, add a 100uF (or higher) capacitor accros  the input positive and negative terminal.

1. Will this drive 3 cree xp-g in series off a 12v supply?

2. You can use it but make sure the LED is not more than 1A (1.5A is still okay)

3. hi,

i'm thinking about buying 10W led witch has forward voltage of 9.0V-11.0V and current up to 900-1050mA.

if i got this right the R will be 1.25V/~1A=1.25R (closest standart is 1.2R).

i want to able to power-up the led from 14V power supply. can i use this circuit of yours with R=1.2ohm and the led will not blow?

thanks.

4. You can use the circuit using your design. 1.2R using 14V to power your 10W LED.

1. May I ask a further question on the 10 watt on this circuit. If I use the input to be a 12 Volt 2 amp driver will the Resistor still be 1.25 R? Thanks, I am a total novice and returning to electronics after 35 years!

5. Hello

Could you modify this LM317 circuit suitable for this led?

5W ir led
Forward voltage: 1.5-1.7V
Forward current: 2400mA
Wave Length: 940nm

Thank you.

6. i want to use 6v battery tell me what should be modified in this cct or any other cct

7. If I would make a 10W LED driver, using the LM317 or 7805 which produces good quality thanks

9. hi,

i'm thinking about buying 10W led witch has forward voltage of 9.0V-11.0V and current up to 900-1050mA.

if i got this right the R will be 1.25V/~1A=1.25R (closest standart is 1.2R).

i want to able to power-up the led from 14V power supply. can i use this circuit of yours with R=1.2ohm and the led will not blow?

thanks.
DH-gmJanuary 31, 2012 at 4:05 PM

You can use the circuit using your design. 1.2R using 14V to power your 10W LED.