Current source for LED.

I'm trying to vary current through a high power LED to vary its brightness. I wonder if there are any current sources that can be controlled with an arduino. Maybe I am overcomplecating and should find a small value pot to chain in series with a current limiting resistor. Is this a good idea?

BTW, I don't want to use PWM. Thanks.

Though you said you don't want to use PWM, have you considered smoothing it with a capacitor to make a DC voltage? That way you could change the voltage on the base of a transistor which changes the current through the LED. Just a thought.

Kyle

You can construct a current source in a variety of ways, using an adjustable voltage regulator for example (e.g., LM317).

But if you're OK with mechanical adjustment through a pot then that sounds easiest.

small value pot to chain in series with a current limiting resistor. Is this a good idea?

Not a good idea as a small value pot would have to be of a very high wattage to be able to cope. It’s even worse if you think you are going to use a digital controlled pot as the can’t handle anything approaching that much current.

PWM is just the turning on and turning off of a digital output.

You can use a digital pot but you’re still doing the same thing as PWM for more money.

http://www.maxim-ic.com/products/digi_pot/

You can’t use a transistor and resistor to do it as its fed by…yes PWM.

In fact you’ve made a crippling limitation on your design by denying PWM.

You could possibly use a resistor ladder

You can use a digital pot but you're still doing the same thing as PWM for more money.

Not sure I understand that. Digital pots work by switching in resistances arranged in chains with an analogue switch. Hence the limit on current.