[ale] Red Hat 6.1 Hard Drive always accessing

[Jhubbs at niit.com (Jeff Hubbs)]

> Yup...LEDiode...current can only flow one way. Your comment 
> is right on.
> -B

Well, yeah, but that doesn't necessarily mean that the circuit it's in won't
behave in an undesired manner if it's turned the wrong way.  When I think of
a simple LED drive circuit, I think of an LED connected to V+ at one end
through a limiting resistor and to the collector of an NPN transistor at the
other end - a transistor whose emitter is connected to ground.  Driven at
its base by a logic level, the transistor would be biased to basically short
the negative end of the LED to ground.  Now, in *that* arrangment, a
reversed LED will give you nothing, but, I guess some mobos use other ways
to drive an LED...

FWIW, all the mobos I've encountered where I had to hook up an HDD LED just
left you with nothing if the LED was hooked up backward, but apparently
there are counterexamples...

- Jeff
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