[sdiy] Using opamps as LED drivers

[Chris McDowell]

Thanks, Dave! Never heard it called a tweak before. makes it sound less desirable, I like it. :)

Chris

(forgot to reply-all, you’ll get this twice Dave!)
On Aug 25, 2014, at 3:33 PM, Dave Brown <davebr at earthlink.net> wrote:

> 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
> 
>