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SubjectRe: PATCH : LEDs - possibly the most pointless kernel subsystem ever
Hi!

> > My construction of LED lights is extremely flaky, and I'm afraid of
> > burning printer port. At 486 days ports were expected to survive such
> > abuse. Not sure if todays EPP/wtf ports can handle that.
>
> parport uses 5V (actually a little less) so if you
> use normal (not extra super duper bright) leds and
> put a 1kOhm resistor in front of each led, then it
> will drain 5mA per led, which gives a total of 40mA
> for eight leds (for example)
>
> now for the parport: depending on the technology
> and the age of the circuit, it provides between
> 2 and 14mA output at >2.4V (the led usually requires
> less than 1.5V to operate) so this would be within
> the range ... but, if you want either extra brightness
> or extra security, you could provide +5V and use
> the outputlines as sink, which then is between
> 15 and 25mA ...
>
> anyway, parport should be short circuit safe, so
> the worst what could happen is, that the leds are
> not working ;) ...

Really? Even for newer designs? I was afraid not to kill
southbridge...


> PS: I usually use 220Ohm and no external power ...

I used 330Ohm and no external power. 8leds were bright (those on data
pins), 4 dim (those on control pins). That was 486, through.

--
Horseback riding is like software...
...vgf orggre jura vgf serr.
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