On Mon, 07 Jul 2014 11:50:21 +0100, Johny B Good wrote:

On Mon, 07 Jul 2014 08:42:13 +0100, Martin Brown
wrote:

On 07/07/2014 08:17, Dave Liquorice wrote:
On Sun, 06 Jul 2014 18:33:10 +0100, alan wrote:

I toned down a blue LED by inking over with a red pen

Why do makers have thse indicator LEDS so bright? On the little (two
thumb size) wireless keyboard they are so bright it makes it hard to
see the keys. Bought a NAS enclosure LED on that lit the room up at
night, attacked it with snips and aditional series resistor. Don't
know what value I ended up at but the current was 50 uA (micro amps)
and it was still a bit bright. The thing would glow dimly if you just
lighly touched the wires with dry fingers.

The LED makers have vastly improved the efficiency of LEDs with time but
electronic engineers still give them about 10mA drive current!

The blue LED indicator lamps are the worse for this excessive
brightness issue. On older kit using different lamp colours, they seem
to have decided on the same value of current limiting resistor for all
three colours (red, green and blue) with the result that the blue is
uncomfortably bright compared to the more muted red and green lamps.

I've found that if I pick a resistor value that uses orange instead
of red as the third band on the originally fitted resistor, that seems
to drop the brightness to a more comparable level. :-)


I have a cute little demo circuit with an original 1970's era red and
yellow LEDs in series with modern ones and the result is startling.

But not as startling for LEDs of a colour other than the blue LED
ime.

This is a massive green LED. Just glad it isn't blue! :-)

Amazing how much advice such a trivial problem has generated. Thanks
everyone.

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