[sdiy] Using opamps as LED drivers

[Dave Brown]

I was taught in school that a circuit designer's worth was inversely
proportional to the number of tweaks he designed in.  I always use the
op-amp current method unless the LED is a simple on/off.  For a one-off DIY,
a tweak is OK, for production, it is costly.

Dave

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Chris McDowell
Sent: Monday, August 25, 2014 1:19 PM
To: synthdiy diy
Subject: [sdiy] Using opamps as LED drivers

Howdy list, 

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 :) 

Cheers,
Chris