[sdiy] Using opamps as LED drivers

[John Speth]

> So, I picked up some bi-color LEDs to play with. To drive them, I put
them in
> the feedback path of a non-inverting op amp configuration, which
compensates
> for the LEDs' forward voltages and works great. LED from output to
negative
> input, 1k resistor from negative input to ground.
>
> Is there any glaring reason why this method isn't great for driving
single
> LEDs? I hardly ever see it done. I generally would use a trim pot and
npn
> driver to get accurate led indication, but now I'm feeling silly for
doing so
> :)

If it works for you, great.  You might not get max LED brightness with a
1K resistor.  Your LED current will be limited by (Vled - Vrail) / 1K.
Make sure your op-amp can drive such a load.

JJS