Re: 12 LED resistance circuit help


"John Fields" <jfields@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:vcuk611q8nljblh2q4bd4tta7uvimhn3pl@xxxxxxxxxx
> On Sat, 23 Apr 2005 05:13:57 GMT, "Anthony Fremont"
> <spam@xxxxxxxxxxxx> wrote:
>
> >
> >"John Bokma" wrote:
> >
> ><snipped exactly what I was going to post>
> >
> >> Note that I did this calculation, later checked it with a voltage
> >meter,
> >> and yet already 2 exotic LEDs died on me. I think it's a bad badge.
> >> (Unless someone can point out my errors).
> >
> >I came up with the same calculation as you. If LEDs are dieing, then
> >20mA may be a bit too much current. Since there are two LEDs in
series,
> >one may hog more current than the other resulting in its demise.
>
> ---
> So, you're saying that because the LEDs may not be identical one may
> be drawing more current than the other?
> ---

Heh. Some advice handed out in the NG is really atrocious, ain't it?

> >You
> >might consider not driving them so hard. There is probably a
relatively
> >insignificant brightness difference between 10mA and 20mA anyway.
>
> --
> John Fields
> Professional Circuit Designer


.

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