Electrical schoolwork...

[Ti Kan]

Huw Powell writes:
> [ ... ] 
> Yes.  If he had stated the current rating, your calculations would have 
> had some merit.  As it was, you introduced an unstated assumption.  As I 
> said above, without the current rating of the LED, you're just winging 
> it.  They do range, after all, over at least an order of magnitude, right?

Not really.  Virtually all small red LEDs I've worked with have an operating
current in the 10mA to 30mA range.  In fact, the 3V forward bias voltage
is sort of an anomaly too, because most small red LEDs are in the
neighborhood of 1.5V.  This also holds true for virtually all small
yellow or green LEDs.  The exceptions are the blue or super bright LEDs.

Since the topic at hand is red LEDs suitable for use behind switch caps
for illumination, the typical current requirement for a small red LED
(appropriate for this type of use) is what I "pulled out of a hat",
based on my experience with working with these devices.

-Ti
2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
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