Re: ATM Brightness of LED

[Dominic-Luc Webb <dlwebb@canit.se>]

Thanks for your challenging thoughts Richard. The LEDs may act as
regulators, but will certainly respond to different voltages. I
think what happens is that there will be differences in linearity
in response to constant voltages versus constant current. The
detector photodiode would be treated as a current source, and
not a voltage source, for an op-amp, for reasons along this line.
Gets tricky since many such devices do not follow Ohm's law....

Dominic


On Fri, 29 Aug 2003, Richard Schwartz wrote:

>
> ----- Original Message -----
> From: "Dominic-Luc Webb" <dlwebb@canit.se>
> To: "Frank Ward" <thewards@mindspring.com>
> Cc: <atm@shore.net>
> Sent: Friday, August 29, 2003 9:30 AM
> Subject: RE: ATM Brightness of LED
>
>
> >
> > On Fri, 29 Aug 2003, Frank Ward wrote:
> >
> > Not always a waste of time, and actually, if you use a
> > voltage regulator, the LED has pretty constant photon flux.
>
> I experimented with LED's and found that da LED itself is a pretty good
> voltage regulator.   Perhaps what it needs for constant brightness is a
> CURRENT regulator.
>
> . . . Richard
>
>
>