PWM-ing a 3W 750ma Luxeon LED
Ever Needed a bright light source for your Robotic Projects.
This Walkthrough will guide you through two Versions.
Version 1 :- Discreet PWM driver, with dimmer control.
Version 2 :- Arduino High speed PWM driver.
There is quite a range of Luxeon Leds to choose from - however they seem to come in 350mA or 750mA versions.
My Project uses a 3W High-Power White LED 130LM version
The Leds heat up quite a bit at full current so a Heatsink is advised.
I used an old CPU heatsink, which i customised.
I also bought a sample pack of lenses that fit over the LED, which produces wide or narrow beams etcetc.
The Best way to drive them is by using a constant current source.
I used a 750mA Constant Current module from Here
I choose this as its reasonable priced and i could not have made at this cost.....
....Plus its PWM enabled - meaning you can adjust the duty cycle to Dim and control the LED.
Version 1 :- Manual PWM LED Control using a LM324 and Variable resistor.
To Drive to the PWM circuit manually i opted for a discreet componant design.
The LM324 opamp can be easily driven from 3V - 32V .... it also lends its self well to PWM.
caution :- if you plan to use a supply voltage over 6V then you will have to limit the
pwm signal voltage level to the PWM module otherwise you will upset or kill the input pin.
The + LED Supply can be anywhere between 6 - 25 Volts
Version 2 :- Arduino Luxeon LED PWM Control
The supplied code is a High speed PWM generator -
(the normal servo PWM signal is too slow and flickers the LED)
// Arduino Highspeed PWM code
// Code_ing Ramps the PWM up&Down (Bright-Dim cycle)
Here is my final circuit (Version1) Hacked and shoehorned into a Bicycle Lamp case_ing.
Not much space to spare.
Still have to workout where to mount the "Beam/Dim Control".
I might even mount it on my bikes "Cow Horns"
Op-Amps Rule.........(Pwm circuit)
I plumped on installing 2*3W Luxeons into the Bicycle casing.
I choose a Wide Beam and a Narrow Beam Lens.
This gives very good light coverage.
My next version will have a barebone arduino installed.