Limit current to LEDs by using diodes

[Tinda]

Hello ，

I'm trying to set up an attiny2313 to drive an array of LEDs and blink them in different patterns. Rather than putting a series of resistors in line with each LED (they'll be controlled separately, so I can't do tricks like putting them in series with each other), I was wondering about just using a couple diodes to get the voltage down to the right range.

The system is running at 3.3V (with a regulator to keep it pretty constant), and two 1N4001 diodes （http://www.kynix.com/Detail/1118317/1N4001G.html）will drop that down to 1.9V - right in line with the lower end of the 1.8 - 2.2V these LEDs are specced for. Since the diodes will always want to maintain the same voltage drop across themselves, I don't have to worry about that voltage changing as I turn the LEDs on or off. Overall I save 6 components.

Has anyone else tried something like this? Is there anything I've overlooked? I realize the diodes will have to dissipate the full current from all the LEDs, but for this small amount of current that doesn't seem like it will be an issue.

Any comments will be grateful.
Great regards.

[Zoltán]

how many leds do you want to drive?
what kind of voltage regulator are you using?

anyways, diodes, once open act basically as shorts, so you won't be able to limit led current with diodes.
Leds are just diodes too, so two shorts in serial is just a piece of wire, which will conduct as much current as the voltage source can provide, until it burns, or melts.
Just use a resistor for each led.