Current(in LED) = 0.7/R2 or R2 =0.7/Current; where this current is the operating current of the LED.
|LED driver schematic|
R1- 1 kilo-ohms resistor 1/2W
Q1- 2N2222 NPN transistor or similar
Q2- IRF530 power mosfet, or similar
DC- 9V to 15V DC
See values of R2 on every LED current and power rating in resistance table below. R2(actual) is the value used in actual circuit.
|R2 resistance table|
If you are planning to use more than 2 LEDs, lets say about 16 power LEDs. We can modify the circuit by simply adding some resistors in our original driver. The value of R is 0.33 ohms 1/2W to 1W. The value of R2 is dependent on the LED current rating and the same values in resistance table above.
How it is done:
For example you have 16pcs of 1W power leds. The leds will be arranged 8 rows with 2 series led per row. You will need also 8 resistors R and 8 resistors R2. The value of R2 is 1 ohm @ 1W based on the table above. R2 will be connected in parallel together, same as diagram below.
|LED driver with parallel LEDs|
1. LED driver using 7805 regulator –one of the cheapest and simplest driver
2. Simple LED driver using LM317 regulator – simplest using 2 main electronic parts, resistor and IC
3. Cheap Power LED Driver – cheapest, uses only resistor, transistor and diode