[Elecraft] K1 LCD Illumination mod

Tue May 14 09:55:01 2002

Hi

It wouldn't matter if its on the 12 or 5 volt supply. If the led is runni=
ng at 20 ma then the power is dissipated in either the limit resistor or =
the regulator so the net result is still 20 ma more on the battery. It is=
 better to keep the extra current off of the regulator so it will run coo=
ler.

There are some very high efficiency LED out there and can be run at 5 - 1=
0 ma with plenty of brightness for night use. look at the HLMP-3950A gree=
n, HLMP - 3750A red, HLMP - 3850A yellow by HP or QT Optoelectronics. I u=
se these led's in several products I make and they are very bright even a=
t low currents. Two of these in series one on each side of the display sh=
ould work well at 5 ma or if you have room try 4 in series. There are som=
e white led's available now that are very bright if you didn't like red, =
green or yellow

Don Brown
KD5NDB

----- Original Message -----
From: Dan Barker
Sent: Tuesday, May 14, 2002 7:43 AM
To: Elecraft
Subject: FW: [Elecraft] K1 LCD Illumination mod

They don't have to be Light-Emitting diodes. You can use plain diodes to =
drop .6 volt each. I guess the dissapation would be the same as a resisto=
r, tho. You guys thinking of putting these accross 12V? I imagine there's=
 5V running around in a K1 (I've got a K2, so I can't look it up as easil=
y). Maybe you'd be able to "discard" only 30% as much "extra" light and/o=
r heat (or the heat comes out in the regulator? Doubt it.).

Dan / WG4S / K2 #2456.

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of John J. McDonough
Sent: Tuesday, May 14, 2002 8:24 AM
To: [email protected]
Cc: Tom Hammond N=D8SS
Subject: Re: [Elecraft] K1 LCD Illumination mod

----- Original Message -----
From: "Tom Hammond N=D8SS" <[email protected]>
Subject: Re: [Elecraft] K1 LCD Illumination mod

> If you placed several of them in series, you could add up to about 8-10
> LEDs with NO increase in current, and you'd not have to dissipate nearl=
y
as
> much heat in the dropping resistor.

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