[sdiy] Speaking of LEDs...

[patchell]

    There is no problem, the diode will always be forward biased, you just need
to make sure you don't exceed the maximum current.

    But, here is a sugestion...if the voltage can go both positive and negative
about ground, use a two lead-bi color LED and tie it to ground instead of -12.
That way, when the voltage is positive, you will get one color, when negative,
another...

Peter Grenader wrote:

> Question for the masters:
>
> How lame is it that I am driving an LED with 20 volts across it and a 2k
> current limit?
>
> We thinks that before too long, it will be blown to smitherens and become a
> zener. I was thinking of putting a few 1N4148's in there in series with it
> to lessen its load.
>
> What I want to do is a cheap and dirty way to show the level of a smooth
> random voltage, which will fluctuate between these two rails (about +8 volts
> to -12).  I am currently driving this with a unity gain op amp.
>
> to see the specific application, go here:
>
> http://www.buzzclick-music.com/sample_hold.jpg
>
> Any suggestions?  OK the way it is?
>
> thanks in advance,
>
> Peter

--
 -Jim
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