Spehro Pefhany wrote:
>
> At 12:05 PM 8/3/01 +0200, you wrote:
>
> >
> >I hope this will be clear. What will a common industrial solution be to this
> >problem?
>
> output                   LED
> push-pull        -------|<|-----[330R]---- +5
>               |/
> ----[10K]-----|     2N3904 etc.
>               |\ E
>                0V
>
> Iled ~= (4.9V - Vf(LED))/330   (so 8-10mA for green/yellow/red)
> Iin = 440uA


Something i've been doing lately is using the
high-intensity leds. The 600mCd, 900 and 1600
leds are getting quite cheap, and they are
EXCELLENT for giving good light at 1mA or less,
even 250uA gives a good indicator. I keep a
drawer full of them and it's surprising how useful
they can be for indicators of special things like
very short pulse lengths (or short PWM) and
for very low current indicators, especially
when testing new circuits and you can't be
bothered to keep attaching the CRO or meter to
it, just put the led in there... Normally they
can be seen from 50uA upward and safe to 50mA.
-Roman

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