**7085 IC**regulator and resistor. Can power led from 0.5W to 3W (5w is also doable) with a wide range of input voltage from 9V to 15V. Current delivered to the led is controlled by the resistor only. Meaning if you plan to change the current capacity (power capacity) of the driver, just replace the value of resistance using the following formula:

**R = (5-Vled) / I;**where I is the current and Vled is forward voltage specified by LED manufacturer and can be found in its datasheet.

For example:

300mA current is needed to power up a 1W LED with voltage drop of 3.3V. You will have:

R = (5-3.3)/0.7 = 5.66 or around 5.6 ohms

driver using 7805 |

1-7805 regulator

1-resistor

- 5.6-ohms 1/2W for 1W led

- 2.0-ohms 2W for 3W led

Note: The maximum current of the 7805 regulator is around 1.5A only but you can modify it to increase its current capacity (see High current 7805 to know how it is done). Take note also the values of current and forward voltage of LED based on the manufacturer's datasheet. Then use the formula above to determine the value of resistor.

Other LED drivers:

1. Simple LED driver using LM317 regulator – simplest using 2

main electronic parts, resistor and IC

2. Cheap Power LED Driver circuit – cheapest, uses only resistor, transistor and diode.

3. High current LED driver using FET – simple, high power and very stable led driver.

my input voltage is 3.50V to 4.15V, I want to make a power led driver for 1W one led.

ReplyDeletemy input voltage is 9 volt and 7805 very hot.

ReplyDeleteso i try 5 volt and its cool and my 3 watt luxeon bright enough. thanks

use heat sink with regulator

Deletejust don't forget to add heatsink in 7805 to dissipate the heat.

ReplyDeletein fact ofcourse this is no different than using an LED with a series resistor

ReplyDeletePlease check your R value calculation...

ReplyDeletePLEASE SIR I NEED YOUR HELP,

ReplyDeleteI want to build Led light of 5 watts with the in put of 12v dc please any help with circuit diagramme

You can use SMR8805 switching mode voltage regulator better replacement of 78xx, it has higher current to drive many more LED, have ~70% less power dissipation, no heat and pin to pin compatible with 7805 :)

ReplyDeleteyou may want to look at http://goo.gl/fbxu8U

whats will be the resistor value with 5w, 7w, 9w, 12w & 15w LED SMD or regulator value also.

ReplyDeleteThe article outlined how to calculate the appropriate resistor value for any LED. Go back and review it. Be careful because I believe there is a typo in his example. "0.7" should be "0.3".

ReplyDeleteYes you are right it should be .3

ReplyDeleteI want to give 230V input to a 5W or 10W SMD LED with 5 to 10 pieces in series/ parallel

ReplyDeleteCitazione: "R = (5-3.3)/0.7 = 5.66 o circa 5,6 ohm"

ReplyDeleteChe cosa indica il valore 0,7?