[sudo-discuss] Dimmable 100W LED Driver Design for Arduino

[Robert Benson]

thank you, jake. i think have all the parts - just need to pull the
inductor, resistor & cap. my plan is to make a pan/tilt/focusable spotlight
controlled by dmx :)

On Sat, Jun 20, 2015 at 7:20 PM, Jake <jake at spaz.org> wrote:

> put two 19v laptop adaptors in series with an n-channel mosfet, and have
> an arduino powered by only the lower 19V adaptor which controls the mosfet.
>
> put an inductor between the transistor and the LED -, and also put a diode
> from the inductor (where it connects to the drain of the mosfet) to the +
> of the LED, where it's connected to the + of the upper 19v laptop adaptor.
> put a good capacitor in parallel with the LED, rated for like 50 volts or
> more.
>
> in the arduino, set the PWM frequency to the highest it will go - a
> divisor of 1 will yield 31 or 62 kHz depending on which pin you use.
>
> connect a knob to one of the analog inputs, and write a program that reads
> the value of the knob and sets the PWM accordingly - although make the
> software limit the maximum PWM according to what you determine is the max
> power the light can handle.
>
> keep the transistor and LED cool.  Remember that the heatsink of the
> transistor must not electrically contact anything else - it is the drain
> (middle pin) electrically.
>
> of course you can write programs to control the brightness from patterns
> you create, instead of just looking at the knob.  Or you can make an audio
> input to one of the analog pins control brightness.  As for controlling
> servos, you can control 2 servos with an arduino pretty easily, on pins 9
> and 10, it's one of the examples that comes with the arduino IDE.
>
> as for the fan, just connect it to one of the 19v power supplies with a
> series resistor so it gets the right amount of power.  If it's a 1w 12v
> fan, you will need a resistor like around 84 ohms, dissipating 0.58 watts.
> A 100 ohm 1w resistor would be fine, or a 50 ohm resistor if you want the
> fan to blow faster.
>
> -jake
>
> On Fri, 19 Jun 2015, Robert Benson wrote:
>
>  I'm trying to drive several devices:
>>
>> 1) 1x 1w 12v fan (pentium 2 cpu cooler)
>> 2) 1x 100w 35v 3a smd led. (I want the led to be dimmable & ideally
>> capable of high
>> frequency switching :))
>>  *  Forward Voltage (VF): DC 32-34V
>>  *  Forward current (IF): 3000MA
>>  *  Out put Lumens: 8000-9500LM
>> 3) several other servo/stepper motors for pan/tilt type uses
>>
>> with one arduino uno.
>>
>> Obviously, the arduino will not power the led so I need a driver for it &
>> maybe even the
>> motors.
>>
>> My research leads me to think that the led wants a constant current of 3
>> amps & a variable
>> voltage for dimming. Circuits of this caliber have not been forthcoming
>> in my searches on
>> the web.
>>
>> Thank you for your consideration. Cheers
>> Robb
>>
>>
>>
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